LAN7850T/8JX - MICROCHIP TECHNOLOGY

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 1

Highlights

• Single Chip Hi-Speed (HS) USB 2.0 to 10/100/

1000 Ethernet Controller

- Integrated Gigabit PHY with HP Auto-MDIX

- Integrated 10/100/1000 Ethernet MAC

(Full-Duplex Support)

- Integrated USB 2.0 Device Controller

- Integrated USB PHY

• Low Power Consumption

- Compliant with Energy Efficient Ethernet

IEEE 802.3az

- Wake on LAN support (WoL)

• Configuration via One Time Programmable (OTP)

Memory

• NetDetach provides automatic USB attach/detach

when Ethernet cable is connected/removed

Target Applications

• Automotive Infotainment

• Notebook/Tablet Docking Stations

• Detachable Laptops

• USB Port Replicators

• Standalone USB to Ethernet Dongles

• Embedded Systems / CE Devices

• Set-Top Boxes / Video Recorders

• Test Instrumentation / Industrial

System Considerations

• Power and I/Os

- Multiple power management features

- 12 GPIOs

- Supports bus and self-powered operation

- Variable voltage I/O supply (1.8V-3.3V)

• Software Support

- Windows 7, 8, 8.1, and 10 driver

- Linux driver

- Mac OS driver

- UEFI support

- PXE support

- Windows line command OTP/EEPROM

programming and testing utility

• Packaging

- Pb-free RoHS compliant 56-pin SQFN (8 x 8 mm)

• Environmental

- Commercial temperature range (0°C to +70°C)

- Industrial temperature range (-40°C to +85°C)

Key Benefits

• USB 2.0 Device Controller

- Supports HS (480 Mbps), and

FS (12 Mbps) modes

- Four endpoints supported

- Supports vendor specific commands

- Remote wakeup supported

- Integrated HSIC interface

• 10/100/1000 Ethernet Controller

- Compliant with IEEE802.3/802.3u/802.3ab/802.3az

-10BASE-T/100BASE-TX/1000BASE-T support

-Full- and half-duplex capability

(only full-duplex operation at 1000 Mbps)

- Controller Modes

-Microsoft AOAC support

(Always On Always Connected)

-Supports Microsoft NDIS 6.2 large send offload

-Full-duplex flow control

-Loop-back modes

-Supports IEEE 802.1q VLAN tagging

-VLAN tag based packet filtering (all 4096 tags)

-Flexible address filtering modes

-33 exact matches (unicast or multicast)

-512-bit hash filter for multicast frames

-Pass all multicast

-Promiscuous unicast/multicast modes

-Inverse filtering

-Pass all incoming with status report

-Supports various statistical counters

-PME pin support

- Frame Features

-Supports 32 wake-up frame patterns

-Preamble generation and removal

-Automatic 32-bit CRC generation and checking

-9 KB jumbo frame support

-Automatic payload padding and pad removal

-Supports Rx/Tx checksum offloads

(IPv4, IPv6, TCP, UDP, IGMP, ICMP)

-Ability to add and strip IEEE 802.1q VLAN tags

LAN7850

Hi-Speed USB 2.0 to 10/100/1000

Ethernet Controller with HSIC

LAN7850

DS00001993D-page 2  2015 - 2017 Microchip Technology Inc.

TO OUR VALUED CUSTOMERS

It is our intention to provide our valued customers with the best documentation possible to ensure successful use of your Microchip

products. To this end, we will continue to improve our publications to better suit your needs. Our publications will be refined and

enhanced as new volumes and updates are introduced.

If you have any questions or comments regarding this publication, please contact the Marketing Communications Department via

E-mail at docerrors@microchip.com. We welcome your feedback.

Most Current Data Sheet

To obtain the most up-to-date version of this data sheet, please register at our Worldwide Web site at:

http://www.microchip.com

You can determine the version of a data sheet by examining its literature number found on the bottom outside corner of any page.

The last character of the literature number is the version number, (e.g., DS30000000A is version A of document DS30000000).

Errata

An errata sheet, describing minor operational differences from the data sheet and recommended workarounds, may exist for cur-

rent devices. As device/documentation issues become known to us, we will publish an errata sheet. The errata will specify the

revision of silicon and revision of document to which it applies.

To determine if an errata sheet exists for a particular device, please check with one of the following:

• Microchip’s Worldwide Web site; http://www.microchip.com

• Your local Microchip sales office (see last page)

When contacting a sales office, please specify which device, revision of silicon and data sheet (include -literature number) you are

using.

Customer Notification System

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 3

LAN7850

1.0 Preface ............................................................................................................................................................................................ 4

2.0 Introduction ..................................................................................................................................................................................... 9

3.0 Pin Descriptions and Configuration ............................................................................................................................................... 10

4.0 Power Connections ....................................................................................................................................................................... 16

5.0 USB Device Controller .................................................................................................................................................................. 17

6.0 FIFO Controller (FCT) ................................................................................................................................................................... 43

7.0 Receive Filtering Engine (RFE) ..................................................................................................................................................... 60

8.0 10/100/1000 Ethernet MAC .......................................................................................................................................................... 75

9.0 Gigabit Ethernet PHY (GPHY) ...................................................................................................................................................... 91

10.0 EEPROM Controller (EEP) ......................................................................................................................................................... 99

11.0 One Time Programmable (OTP) Memory ................................................................................................................................. 122

12.0 Resets ....................................................................................................................................................................................... 123

13.0 Clocks and Power management (CPM) .................................................................................................................................... 126

14.0 Power Management Event (PME) Operation ............................................................................................................................ 136

15.0 Register Descriptions ................................................................................................................................................................ 140

16.0 Operational Characteristics ....................................................................................................................................................... 262

17.0 Package Information ................................................................................................................................................................. 270

18.0 Revision History ........................................................................................................................................................................ 273

LAN7850

DS00001993D-page 4  2015 - 2017 Microchip Technology Inc.

1.0 PREFACE

1.1 General Terms

TABLE 1-1: GENERAL TERMS

Term Description

10BASE-T 10 Mbps Ethernet, IEEE 802.3 compliant

100BASE-TX 100 Mbps Fast Ethernet, IEEE802.3u compliant

1000BASE-T 100 Mbps Fast Ethernet, IEEE802.3ab compliant

ADC Analog-to-Digital Converter

AFE Analog Front End

ALR Address Logic Resolution

AN Auto-Negotiation

AOAC Always on Always Connected

ARP Address Resolution Protocol

BELT Best Effort Latency Tolerance

BLW Baseline Wander

Byte 8 bits

CPM Clocks and Power Management

CSMA/CD Carrier Sense Multiple Access/Collision Detect

CSR Control and Status Registers

CTR Counter

DA Destination Address

DWORD 32 bits

EC Embedded Controller

EEE Energy Efficient Ethernet

EP USB Endpoint

EPC EEPROM Controller

FCS Frame Check Sequence - The extra checksum characters added to the end of an

Ethernet frame, used for error detection and correction.

FCT FIFO Controller

FIFO First In First Out buffer

FS Full Speed

FSM Finite State Machine

FW Firmware

GMII Gigabit Media Independent Interface

GPIO General Purpose I/O

GPHY Gigabit Ethernet Physical Layer

Host External system (Includes processor, application software, etc.)

HS High Speed

HW Hardware. Refers to function implemented by digital logic.

IGMP Internet Group Management Protocol

Inbound Refers to data input to the device from the host

LDO Linear Drop-Out Regulator

Level-Triggered Sticky Bit This type of status bit is set whenever the condition that it represents is asserted. The

bit remains set until the condition is no longer true and the status bit is cleared by writ-

ing a zero.

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 5

LAN7850

LFPS Low Frequency Periodic Signal

LFSR Linear Feedback Shift Register

LPM Link Power Management

lsb Least Significant Bit

LSB Least Significant Byte

LTM Latency Tolerance Messaging

MAC Media Access Controller

MDI Medium Dependent Interface

MDIX Media Dependent Interface with Crossover

MEF Multiple Ethernet Frames

MII Media Independent Interface

MIIM Media Independent Interface Management

MIL MAC Interface Layer

MLD Multicast Listening Discovery

MLT-3 Multi-Level Transmission Encoding (3-Levels). A tri-level encoding method where a

change in the logic level represents a code bit “1” and the logic output remaining at the

same level represents a code bit “0”.

msb Most Significant Bit

MSB Most Significant Byte

NRZI Non Return to Zero Inverted. This encoding method inverts the signal for a “1” and

leaves the signal unchanged for a “0”

N/A Not Applicable

NC No Connect

OTP One Time Programmable

OUI Organizationally Unique Identifier

Outbound Refers to data output from the device to the host

PCS Physical Coding Sublayer

PHY Physical Layer

PISO Parallel In Serial Out

PLL Phase Locked Loop

PMD Physical Medium Dependent

PME Power Management Event

PMIC Power Management IC

POR Power on Reset

PTP Precision Time Protocol

QWORD 64 bits

RESERVED Refers to a reserved bit field or address. Unless otherwise noted, reserved bits must

always be zero for write operations. Unless otherwise noted, values are not guaran-

teed when reading reserved bits. Unless otherwise noted, do not read or write to

reserved addresses.

RFE Receive Filtering Engine

RGMII Reduced Gigabit Media Independent Interface

RMON Remote Monitoring

RMII Reduced Media Independent Interface

RST Reset

RTC Real-Time Clock

TABLE 1-1: GENERAL TERMS (CONTINUED)

Term Description

LAN7850

DS00001993D-page 6  2015 - 2017 Microchip Technology Inc.

SA Source Address

SCSR System Control and Status Registers

SEF Single Ethernet Frame

SFD Start of Frame Delimiter - The 8-bit value indicating the end of the preamble of an

Ethernet frame.

SIPO Serial In Parallel Out

SMI Serial Management Interface

SMNP Simple Network Management Protocol

SQE Signal Quality Error (also known as “heartbeat”)

SSD Start of Stream Delimiter

TMII Turbo Media Independent Interface

UDP User Datagram Protocol - A connectionless protocol run on top of IP networks

URX USB Bulk-Out Receiver

USB Universal Serial Bus

UTX USB Bulk-In Transmitter

UUID Universally Unique IDentifier

VSM Vendor Specific Messaging

WORD 16 bits

ZLP Zero Length USB Packet

TABLE 1-1: GENERAL TERMS (CONTINUED)

Term Description

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 7

LAN7850

1.2 Buffer Types

TABLE 1-2: BUFFER TYPES

Buffer Type Description

VIS Variable voltage Schmitt-triggered input

O8 Output with 8 mA sink and 8 mA source

OD8 Open-drain output with 8 mA sink

O12 Output with 12 mA sink and 12 mA source

OD12 Open-drain output with 12 mA sink

HSIC High-Speed Inter-Chip (HSIC) USB Electrical Specification compliant input/output

PU 50 μA (typical) internal pull-up. Unless otherwise noted in the pin description, internal pull-

ups are always enabled.

Note: Internal pull-up resistors prevent unconnected inputs from floating. Do not rely on

internal resistors to drive signals external to the device. When connected to a

load that must be pulled high, an external resistor must be added.

PD 50 μA (typical) internal pull-down. Unless otherwise noted in the pin description, internal

pull-downs are always enabled.

Note: Internal pull-down resistors prevent unconnected inputs from floating. Do not rely

on internal resistors to drive signals external to the device. When connected to a

load that must be pulled low, an external resistor must be added.

AI Analog Input

AIO Analog bidirectional

ICLK Crystal oscillator input pin

OCLK Crystal oscillator output pin

P Power pin

LAN7850

DS00001993D-page 8  2015 - 2017 Microchip Technology Inc.

1.3 Register Nomenclature

TABLE 1-3: REGISTER NOMENCLATURE

RRead: A register or bit with this attribute can be read.

WWrite: A register or bit with this attribute can be written.

RO Read only: Read only. Writes have no effect.

RS Read to Set: This bit is set on read.

RC Read to Clear: Contents is cleared after the read. Writes have no effect.

WO Write only: If a register or bit is write-only, reads will return unspecified data.

WC Write One to Clear: Writing a one clears the value. Writing a zero has no effect

WAC Write Anything to Clear: Writing anything clears the value.

LL Latch Low: Clear on read of register.

LH Latch High: Clear on read of register.

SC Self-Clearing: Contents are self-cleared after the being set. Writes of zero have no

effect. Contents can be read.

SS Self-Setting: Contents are self-setting after being cleared. Writes of one have no

effect. Contents can be read.

RO/LH Read Only, Latch High: This mode is used by the Ethernet PHY registers. Bits with

this attribute will stay high until the bit is read. After it is read, the bit will remain high,

but will change to low if the condition that caused the bit to go high is removed. If the

bit has not been read, the bit will remain high regardless of a change to the high condi-

tion.

NALR Not Affected by Lite Reset. The state of NASR bits do not change on assertion of a

lite reset.

NASR Not Affected by Software Reset. The state of NASR bits do not change on assertion

of a software reset.

RESERVED Reserved Field: Reserved fields must be written with zeros, unless otherwise indi-

cated, to ensure future compatibility. The value of reserved bits is not guaranteed on a

read.

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 9

LAN7850

2.0 INTRODUCTION

2.1 General Description

The LAN7850 is a high performance Hi-SpeedUSB 2.0 to 10/100/1000 Ethernet controller with an integrated 10/100/

1000 Ethernet PHY and High-Speed Inter-Connect (HSIC) interface. With applications ranging from notebook/tablet

docking stations, set-top boxes, and PVRs, to USB port replicators, USB to Ethernet dongles, embedded systems, and

test instrumentation, the LAN7850 is a high performance and cost effective USB/HSIC to Ethernet connectivity solution.

The LAN7850 contains an integrated 10/100/1000 Ethernet MAC and PHY, Filtering Engine, USB PHY (with HSIC inter-

face), Hi-Speed USB 2.0 device controller, TAP controller, EEPROM controller, and a FIFO controller with internal

packet buffering.

The internal USB 2.0 device controller and USB PHY are compliant with the USB 2.0 Hi-Speed standard. The LAN7850

implements Control, Interrupt, Bulk-in, and Bulk-out USB Endpoints.

The Ethernet controller supports auto-negotiation, auto-polarity correction, HP Auto-MDIX, and is compliant with the

IEEE 802.3, IEEE 802.3u, IEEE 802.3ab, and 802.3az (Energy Efficient Ethernet) standards. ARP and NS offload are

also supported.

Multiple power management features are provided, including Energy Efficient Ethernet (IEEE 802.3az), support for Mic-

rosoft’s Always On Always Connected (AOAC), and “Magic Packet”, “Wake On LAN”, and “Link Status Change” wake

events. Wake events can be programmed to initiate a USB remote wakeup. Up to 32 different AOAC wake-up frame

patterns are supported along with Microsoft’s WPD (Whole Packet Detection).

An internal EEPROM controller exists to load various USB and Ethernet configuration parameters. For EEPROM-less

applications, the LAN7850 provides 1K Bytes of OTP memory that can be used to preload this same configuration data

before enumeration. The integrated IEEE 1149.1 compliant TAP controller provides boundary scan via JTAG.

The LAN7850 is available in commercial and industrial temperature range versions. An internal block diagram of the

LAN7850 is shown in Figure 2-1.

FIGURE 2-1: INTERNAL BLOCK DIAGRAM

LAN7850

DS00001993D-page 10  2015 - 2017 Microchip Technology Inc.

3.0 PIN DESCRIPTIONS AND CONFIGURATION

3.1 Pin Assignments

FIGURE 3-1: PIN ASSIGNMENTS (TOP VIEW)

Note: When an “_N” is used at the end of the signal name, it indicates that the signal is active low. For example,

RESET_N indicates that the reset signal is active low.

The buffer type for each signal is indicated in the “Buffer Type” column of the pin description tables in Sec-

tion 3.2, "Pin Descriptions". A description of the buffer types is provided in Section 1.2, "Buffer Types".

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 11

LAN7850

TABLE 3-1: PIN ASSIGNMENTS

Pin Number Pin Name Pin Number Pin Name

1TR0P 29 CONNECT/GPIO6

2TR0N 30 HSIC_SEL

3VDD25A 31 LED0/GPIO7

4TR1P 32 PME_MODE/GPIO8

5TR1N 33 VDD12A

6VDD25A 34 VDD12HSIC

7TR2P 35 STROBE

8TR2N 36 USB_DP

9VDD25A 37 USB_DM

10 TR3P 38 DATA

11 TR3N 39 PME_N

12 VDD25A 40 TEST

13 VDDVARIO 41 RESET_N/PME_CLEAR

14 TDI 42 VDDVARIO

15 TDO 43 USBRBIAS

16 TCK/GPIO0 44 VDD33A

17 TMS 45 VDDVARIO

18 VDD12_SW_OUT 46 XI

19 VDD_SW_IN 47 XO

20 VDD12_SW_FB 48 VDD12CORE

21 EECS/GPIO1 49 LED1/GPIO9

22 EEDI/GPIO2 50 LED2/GPIO10

23 EEDO/GPIO3 51 LED3/GPIO11

24 EECLK/GPIO4 52 VDD12A

25 VDDVARIO 53 VDD25_REG_OUT

26 VDD12CORE 54 VDD33_REG_IN

27 VBUS_DET 55 REF_REXT

28 SUSPEND_N/GPIO5 56 REF_FILT

Exposed Pad (VSS) must be connected to ground

LAN7850

DS00001993D-page 12  2015 - 2017 Microchip Technology Inc.

3.2 Pin Descriptions

TABLE 3-2: PIN DESCRIPTIONS

Name Symbol Buffer

Type Description

Gigabit Ethernet Pins

Ethernet TX/RX

Positive Channel 0

TR0P AIO Transmit/Receive Positive Channel 0.

Ethernet TX/RX

Negative Channel 0

TR0N AIO Transmit/Receive Negative Channel 0.

Ethernet TX/RX

Positive Channel 1

TR1P AIO Transmit/Receive Positive Channel 1.

Ethernet TX/RX

Negative Channel 1

TR1N AIO Transmit/Receive Negative Channel 1.

Ethernet TX/RX

Positive Channel 2

TR2P AIO Transmit/Receive Positive Channel 2.

Ethernet TX/RX

Negative Channel 2

TR2N AIO Transmit/Receive Negative Channel 2.

Ethernet TX/RX

Positive Channel 3

TR3P AIO Transmit/Receive Positive Channel 3.

Ethernet TX/RX

Negative Channel 3

TR3N AIO Transmit/Receive Negative Channel 3.

External PHY

Reference Filter

REF_FILT AI External PHY Reference Filter. Connect to an external 1uF

capacitor to ground.

External PHY

Reference Resistor

REF_REXT AI External PHY Reference Resistor. Connect to an external 2K

1.0% resistor to ground.

USB Pins

USB 2.0

DPLUS

USB_DP AIO Hi-Speed USB data plus.

USB 2.0

DMINUS

USB_DM AIO Hi-Speed USB Speed data minus.

External USB

Bias Resistor

USBRBIAS AI Used for setting HS transmit current level and on-chip termi-

nation impedance. Connect to an external 12K 1.0% resistor

to ground.

HSIC STROBE STROBE HSIC Bi-directional data strobe signal as defined in the High-

Speed Inter-Chip USB Electrical Specification.

HSIC DATA DATA HSIC Bi-directional Double Data Rate (DDR) data signal that is

synchronous to the STROBE signal as defined in the High-

Speed Inter-Chip USB Electrical Specification.

Miscellaneous Pins

Detect Upstream

VBUS Power

VBUS_DET VIS

(PD)

Detects the state of the upstream bus power.

For bus powered operation, this pin must be tied to VDD33A.

Refer to Section 4.0, "Power Connections" for additional

information.

USB Connect CONNECT O12 This pin asserts when the device is attempting to attach to

the USB host.

This pin is intended to help address a known bug on existing

HSIC host controllers where the HSIC connect signaling is

missed.

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 13

LAN7850

HSIC Select HSIC_SEL VIS When tied to VDD, the device HSIC interface is enabled.

Otherwise, the USB 2.0 interface is enabled.

Note: This is a static signal that may not be changed at

run time.

PME PME_N O8/OD8 This pin is used to signal PME when the PME mode of oper-

ation is in effect.

PME Mode Select PME_MODE VIS This pin serves as the PME mode selection input when the

PME mode of operation is in effect.

PME Clear PME_CLEAR VIS This pin may serves as PME clear input when the PME

mode of operation is in effect.

USB Suspend SUSPEND_N O12 This pin is asserted when the device is in one of the suspend

states as defined in Section 13.3, "Suspend States".

This pin may be configured to place an external switcher into

a low power state such as when the device is in SUSPEND2.

General Purpose

I/O 0-11

GPIO[0:11] VIS/O8/

OD8

(PU)

These general purpose I/O pins are each fully programmable

as either a push-pull output, an open-drain output, or a

Schmitt-triggered input. A programmable pull-up may option-

ally be enabled.

Indicator LEDs 0-3 LED[0:3] OD12 These LEDs can be configured to indicate Ethernet link,

activity, duplex, and collision. Refer to Section 9.3, "LED

Interface," on page 94 for additional information.

System Reset RESET_N VIS System reset. This pin is active low.

If this signal is unused it must be pulled-up to VDD.

Test Pin TEST VIS Test pin. This pin is used for internal purposes only and must

be connected to ground for proper operation.

EEPROM

Chip Select

EECS O12 This pin drives the chip select output of the external

EEPROM.

EEPROM Data In EEDI VIS This pin is driven by the EEDO output of the external

EEPROM.

EEPROM Data Out EEDO O12 This pin drives the EEDI input of the external EEPROM.

EEPROM Clock EECLK O12 This pin drives the EEPROM clock of the external EEPROM.

JTAG

Test Mode Select

TMS VIS JTAG test mode select.

JTAG

Test Clock

TCK VIS JTAG test clock.

The maximum operating frequency of this clock is half of the

system clock.

JTAG

Test Data Input

TDI VIS JTAG data input.

JTAG

Test Data Output

TDO O12 JTAG data output.

TABLE 3-2: PIN DESCRIPTIONS (CONTINUED)

Name Symbol Buffer

Type Description

LAN7850

DS00001993D-page 14  2015 - 2017 Microchip Technology Inc.

Clock Interface

Crystal Input XI ICLK External 25 MHz crystal input.

Note: This pin can also be driven by a single-ended

clock oscillator. When this method is used, XO

should be left unconnected.

Crystal Output XO OCLK External 25 MHz crystal output.

I/O Power pins, Core Power Pins, and Ground Pad

Variable I/O Power

Supply Input

VDDVARIO P +1.8V - +3.3V variable supply for I/Os.

Refer to Section 4.0, "Power Connections," on page 16 for

connection information.

+3.3V Analog

Power Supply Input

VDD33A P +3.3V analog power supply for USB 2.0 AFE.

Refer to Section 4.0, "Power Connections," on page 16 for

connection information.

+2.5V Analog

Power Supply Input

VDD25A P +2.5V analog power supply input for Gigabit Ethernet PHY.

Refer to Section 4.0, "Power Connections," on page 16 for

connection information.

+1.2V Ethernet Port

Power Supply Input

VDD12A P +1.2V analog power supply input for USB PLL/AFE.

Refer to Section 4.0, "Power Connections," on page 16 for

connection information.

+1.2V Digital Core

Power Supply Input

VDD12CORE P +1.2V digital core power supply input.

Refer to Section 4.0, "Power Connections," on page 16 for

connection information.

+1.2V HSIC Power

Supply Input

VDD12HSIC P +1.2V HSIC power supply input.

Refer to Section 4.0, "Power Connections," on page 16 for

connection information.

+3.3V LDO Input

Voltage

VDD33_REG_IN P +3.3V power supply input to the integrated LDO.

Refer to Section 4.0, "Power Connections," on page 16 for

connection information.

+2.5V LDO Output VDD25_REG_OUT P +2.5V power supply output from the integrated LDO. This is

used to supply power to Gigabit Ethernet PHY AFE.

Refer to Section 4.0, "Power Connections," on page 16 for

connection information.

Switcher Input

Voltage

VDD_SW_IN P +3.3V input voltage for switching regulator.

Refer to Section 4.0, "Power Connections," on page 16 for

connection information.

Switcher Feedback VDD12_SW_FB P Feedback pin for the integrated switching regulator.

Refer to Section 4.0, "Power Connections," on page 16 for

connection information.

Note: To disable the switcher, tie this pin to

VDD_SW_IN.

TABLE 3-2: PIN DESCRIPTIONS (CONTINUED)

Name Symbol Buffer

Type Description

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 15

LAN7850

+1.2V Switcher

Output Voltage

VDD12_SW_OUT P +1.2V power supply output voltage for switching regulator.

Refer to Section 4.0, "Power Connections," on page 16 for

connection information.

Ground VSS P Common Ground

TABLE 3-2: PIN DESCRIPTIONS (CONTINUED)

Name Symbol Buffer

Type Description

LAN7850

DS00001993D-page 16  2015 - 2017 Microchip Technology Inc.

4.0 POWER CONNECTIONS

Figure 4-1 illustrates the device power connections in a typical application. Refer to the device reference schematic for

additional information. Refer to Section 3.0, "Pin Descriptions and Configuration," on page 10 for additional pin informa-

tion.

FIGURE 4-1: POWER CONNECTION DIAGRAM

Note: For 3.3V I/O operation, the VDDVARIO and +3.3V supplies may be connected together.

To disable the internal switcher, tie the VDD12_SW_FB pin to 3.30V and ensure that all VDD12 rails are

connected to an external 1.20V supply.

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 17

LAN7850

5.0 USB DEVICE CONTROLLER

5.1 Overview

The USB functionality consists of five major parts. The USB PHY, UDC (USB Device Controller), URX (USB Bulk Out

Receiver), UTX (USB Bulk In Transmitter), and CTL (USB Control Block).

The UDC is configured to support one configuration, one interface, one alternate setting, and four endpoints. Streams

are not supported in this device. The URX and UTX implement the Bulk-Out and Bulk-In endpoints respectively. The

CTL manages Control and Interrupt endpoints.

Each USB Controller endpoint is unidirectional with even numbered endpoints handling the OUT (from the host, actually

RX into the device) direction and odd numbered endpoints handling the IN (to the host, actually TX from the device)

direction.

The UDC endpoint numbers start at 0 and increment. Endpoint numbers are not skipped and have a fixed mapping to

the USB endpoint numbers. The corresponding USB endpoint is obtained by dividing the UDC endpoint number by 2

(rounding down). For example, single directional endpoint 0 indicates USB OUT endpoint 0, and single directional end-

point 1 corresponds to USB IN endpoint 0.

The mapping of the device’s USB endpoints to the UDC endpoints is shown in Table 5-1. As can be seen, one IN and

two OUT endpoints on the UDC are not utilized.

5.2 Control Endpoint

The Control endpoint is handled by the CTL (USB Control) module. The CTL module is responsible for handling stan-

dard USB requests, as well as USB vendor commands. The UDC does not handle USB commands. These commands

are passed to the CTL for completion.

5.2.1 USB STANDARD COMMAND PROCESSING

This section lists the supported USB standard device requests. The basic format of a device request is shown in section

9.3 of the USB 2.0 specification and the standard device requests are described in section 9.4. Valid values of the

parameters are given below.

Per the USB specifications, if an unsupported or invalid request is made to a USB device, the device responds by return-

ing STALL in the Data or Status stage of the request. Receipt of an unsupported or invalid request does NOT cause the

optional Halt feature on the control pipe to be set.

For each request supported, the USB specifications provide details on the device behavior during the various configu-

ration states and on the conditions which will return a Request Error. Some requests affect the state of the hardware.

In order to implement the Get Descriptor command, the CTL manages a 128x32 Descriptor RAM. The RAMs contents

are initialized via the EEPROM or OTP, after a system reset occurs. The Descriptor RAM may also be programmed by

the device driver to support EEPROM-Less mode.

TABLE 5-1: DEVICE TO UDC ENDPOINT MAPPING

Endpoint Function USB EP number

Control OUT 0

Control IN 0

unused NA

Bulk IN 1

Bulk OUT 2

unused NA

Interrupt IN 3

LAN7850

DS00001993D-page 18  2015 - 2017 Microchip Technology Inc.

When the UDC decodes a Get Descriptor command, it will pass a pointer to the CTL. The CTL uses this pointer to deter-

mine what the command is and how to fill it.

5.2.1.1 Clear Feature

bmRequestType - 00h for the device, 01h for interfaces and 02h for endpoints.

wValue - Specifies the feature, 1=Device_Remote_Wakeup and 0=Endpoint_Halt.

wIndex - Always 0 when the device is selected, specifies the interface number (always 0) when an interface is selected

or the direction/endpoint number (0, 80h, 81h, 2 or 83h) when an endpoint is selected.

A ClearFeature(Endpoint_Halt) request will clear the USB 2.0 data toggle for the specified endpoint.

5.2.1.2 Get Configuration

All parameters are fixed per the USB specifications.

5.2.1.3 Get Descriptor

wValue - The high byte selects the descriptor type. The supported descriptors for this command are 1=Device, 2=Con-

figuration (including Interface, Endpoint descriptors and Endpoint Companion descriptors (USB 2.1 LPM)), 3=String,

6=Device Qualifier (HS/FS), 7=Other Speed Configuration (USB2.0). The low byte selects the descriptor index and must

be 0.

wIndex - Specifies the Language ID for string descriptors or is 0 for other descriptors.

wLength - Specifies the number of bytes to return. If the descriptor is longer than the wLength field, only the initial bytes

of the descriptor are returned. If the descriptor is shorter than the wLength field, the device indicates the end of the con-

trol transfer by sending a short packet when further data is requested. A short packet is defined as a packet shorter than

the maximum payload size or a zero length data packet.

5.2.1.4 Get Interface

wIndex - Specifies the interface, always 0 for this device.

5.2.1.5 Get Status

bmRequestType - 00h for the device, 01h for interfaces and 02h for endpoints.

wIndex - Always 0 when the device is selected, specifies the interface number (always 0) when an interface is selected

or the direction/endpoint number (0, 80h, 81h, 2 or 83h) when an endpoint is selected.

TABLE 5-2: STRING DESCRIPTOR INDEX MAPPINGS

INDEX STRING NAME

0 Language ID

1 Manufacturer ID

2 Product ID

3 Serial Number

4 Configuration String

5 Interface String

Note: Direct access to the Interface, Endpoint and Endpoint Companion (USB 2.1 LPM) descriptors are not sup-

ported by this command and will cause a USB stall.

Note: Power Method (PWR_SEL) in Hardware Configuration Register (HW_CFG) is used as the source for the

Self-Power bit (D0).

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 19

LAN7850

5.2.1.6 Set Address

wValue - Specifies the new device address.

Per the USB specification, the USB device does not change its device address until after the Status stage of this request

is completed successfully. This is a difference between this request and all other requests. For all other requests, the

operation indicated must be completed before the Status stage.

5.2.1.7 Set Configuration

wValue - The lower byte specifies the configuration value.

The device supports only one configuration. A value of 1 places the device into the Configured state while a value of 0

places the device into the Address state.

The Halt feature is reset for all endpoints upon the receipt of this request with a valid configuration value.

The USB 2.0 data toggle for all endpoints are initialized upon the receipt of this request with a valid configuration value.

5.2.1.8 Set Descriptor

This optional request is not supported and the device responds by returning STALL.

5.2.1.9 Set Feature

bmRequestType - 00h for the device, 01h for interfaces and 02h for endpoints.

wValue - Specifies the feature, 1=Device_Remote_Wakeup, 2=device Test_Mode, 0=Endpoint_Halt.

wIndex - Specifies the interface number (always 0) when an interface is selected or the direction/endpoint number (81h,

2 or 83h) when an endpoint is selected. When the device is selected, this field is always 0 unless device Test_Mode is

selected via wValue, in which case the upper byte is the Test Selector and the lower byte a 0.

5.2.1.10 Set Interface

wValue - Specifies the alternate setting (must be 0).

wIndex - Specifies the interface (always 0).

Only one interface with one setting is supported by the device. If the command is issued with an

interface other than 00h, the device responds with a Request Error. If the command is issued with an

interface setting of 00h but with an alternative setting other than 00h, the device responds with a

STALL.

The Halt feature is reset for all endpoints upon the receipt of this request with valid interface and

alternate setting values.

The USB 2.0 data toggle for all endpoints are initialized upon the receipt of this request with valid

interface and alternate setting values.

5.2.1.11 Set Isochronous Delay

This command is not supported. The device will respond with a Stall to this request.

5.2.1.12 Set SEL

This command is not supported. The device will respond with a Stall to this request.

5.2.1.13 Sync Frame

There are no isochronous endpoints in this device. The device will respond with a Stall to this request.

5.2.2 USB VENDOR COMMANDS

The device implements several vendor specific commands in order to directly access CSRs and efficiently gather sta-

tistics. The memory map utilized by the address field is defined in Table 15-1, “Memory Map,” on page 140.

Note: Endpoint_Halt is not implemented for Endpoint 0.

LAN7850

DS00001993D-page 20  2015 - 2017 Microchip Technology Inc.

5.2.2.1 Write Command

This command allows the Host to write a memory location. Burst writes are not supported. All writes are 32-bits.

5.2.2.2 Read Command

This command allows the Host to read a memory location. Burst reads are not supported. All reads return 32-bits.

5.2.2.3 Get Statistics Command

The Get Statistics Command returns the entire contents of the RX and TX statistics counters. The statistics counters

are snapshot when fulfilling the command request. The statistics counters rollover.

TABLE 5-3: FORMAT OF WRITE SETUP STAGE

Offset Field Value

0h bmRequestType 40h

1h bRequest A0h

2h wValue 00h

4h wIndex {Address[12:0]}

6h wLength 04h

TABLE 5-4: FORMAT OF WRITE DATA STAGE

Offset Field

0h Register Write Data [31:0]

TABLE 5-5: FORMAT OF READ SETUP STAGE

Offset Field Value

0h bmRequestType C0h

1h bRequest A1h

2h wValue 00h

4h wIndex {Address[12:0]}

6h wLength 04h

TABLE 5-6: FORMAT OF READ DATA STAGE

Offset Field

0h Register Read Data [31:0]

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 21

LAN7850

Note: TX statistics counters are not affected by frames sent in response to NS/ARP requests when the device is

suspended.

Good byte and received frame counters will count all frames that are delivered to the Host. If Store Bad

Frames is set in the FIFO Controller RX FIFO Control Register (FCT_RX_CTL) any bad frames received

will be counted as well.

The statistics counters are cleared by all reset events including LRST.

TABLE 5-7: FORMAT OF GET STATISTICS SETUP STAGE

Offset Field Value

0h bmRequestType C0h

1h bRequest A2h

2h wValue 00h

4h wIndex 00h

6h wLength BCh

TABLE 5-8: FORMAT OF GET STATISTICS DATA STAGE

Offset Field

00h RX FCS Errors

04h RX Alignment Errors

08h Rx Fragment Errors

0Ch RX Jabber Errors

10h RX Undersize Frame Errors

14h RX Oversize Frame Errors

18h RX Dropped Frames

1Ch RX Unicast Byte Count

20h RX Broadcast Byte Count

24h RX Multicast Byte Count

28h RX Unicast Frames

2Ch RX Broadcast Frames

30h RX Multicast Frames

34h RX Pause Frames

38h RX 64 Byte Frames

3Ch RX 65 - 127 Byte Frames

LAN7850

DS00001993D-page 22  2015 - 2017 Microchip Technology Inc.

40h RX 128 - 255 Byte Frames

44h RX 256 - 511 Bytes Frames

48h RX 512 - 1023 Byte Frames

4Ch RX 1024 - 1518 Byte Frames

50h RX Greater 1518 Byte Frames

54h EEE RX LPI Transitions

58h EEE RX LPI Time

5Ch TX FCS Errors

60h TX Excess Deferral Errors

64h TX Carrier Errors

68h TX Bad Byte Count

6Ch TX Single Collisions

70h TX Multiple Collisions

74h TX Excessive Collision

78h TX Late Collisions

7Ch TX Unicast Byte Count

80h TX Broadcast Byte Count

84h TX Multicast Byte Count

88h TX Unicast Frames

8Ch TX Broadcast Frames

90h TX Multicast Frames

94h TX Pause Frames

98h TX 64 Byte Frames

9Ch TX 65 - 127 Byte Frames

A0h TX 128 - 255 Byte Frames

A4h TX 256 - 511 Bytes Frames

A8h TX 512 - 1023 Byte Frames

ACh TX 1024 - 1518 Byte Frames

B0h TX Greater 1518 Byte Frames

B4h EEE TX LPI Transitions

B8h EEE TX LPI Time

TABLE 5-8: FORMAT OF GET STATISTICS DATA STAGE (CONTINUED)

Offset Field

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 23

LAN7850

TABLE 5-9: STATISTICS COUNTER DEFINITIONS

Name Description Size

(Bits)

RX FCS Errors Number of frames received with CRC-32 errors or RX errors.

Note: If a frame has a Jabber Error and FCS error, only the RX

Jabber Errors counter will be incremented

Note: If a frame is less than 64 bytes in length and has an FCS

error, only the RX Fragment Errors counter will be

incremented.

RX Alignment Errors Number of RX frames received with alignment errors. 20

RX Fragment Errors Number of frames received that are < 64 bytes in size and have an

FCS error or RX error.

Note: If a frame is less than 64 bytes in length and has an FCS

error, only the RX Fragment Errors counter will be

incremented.

RX Jabber Errors Number of frames received with a length greater than Maximum

Frame Size (MAX_SIZE) and have FCS errors or RX errors.

Note: The existence of extra bits does not trigger a jabber error.

A jabber error requires at least one full byte beyond the

value specified by the Maximum Frame Size (MAX_SIZE)

to be received.

Note: If a frame has a Jabber Error and FCS error, only the RX

Jabber Errors counter will be incremented.

RX Undersize Frame Errors Number of frames received with a length less than 64 bytes. No other

errors have been detected in the frame.

RX Oversize Frame Errors Number of frames received with a length greater than the

programmed maximum Ethernet frame size (Maximum Frame Size

(MAX_SIZE) field of the MAC Receive Register (MAC_RX)). No

other errors have been detected in the frame.

Note: The VLAN Frame Size Enforcement (FSE) bit allows for the

maximum legal size to be increased by 4-bytes to account

for a single VLAN tag or 8-bytes to account for stacked

VLAN tags.

Note: The MAC determines a VLAN tag is present if the type field

is equal to 8100h or the value programmed in the VLAN

Type Register (VLAN_TYPE).

Note: The existence of extra bits does not trigger an oversize

error. An oversize error requires at least one full byte

beyond the value specified by the Maximum Frame Size

(MAX_SIZE) to be received.

RX Dropped Frames Number of RX frames dropped by the FCT due to insufficient room

in the RX FIFO.

Note: If a frame to be dropped has an Ethernet error, it will be

counted in the relevant bad frame counter. The RX Dropped

Frames counter will be incremented for the errored frame

only if Store Bad Frames is set in the FIFO Controller RX

FIFO Control Register (FCT_RX_CTL).

LAN7850

DS00001993D-page 24  2015 - 2017 Microchip Technology Inc.

RX Unicast Byte Count Total number of bytes received from unicast frames without errors.

This counter does not count frames that fail address filtering. Pause

frames filtered by Forward Pause Frames (FPF) are not counted.

Frames that are discarded from FIFO overflow are not counted.

Note: The per frame byte count does not include the VLAN TAG

and VID if the Enable VLAN Tag Stripping bit is set in the

Receive Filtering Engine Control Register (RFE_CTL). It

does not include the FCS if the FCS Stripping bit is set in

the MAC Receive Register (MAC_RX).

RX Broadcast Byte Count Total number of bytes received from broadcast frames without errors.

This counter does not count broadcast frames received when the

Accept Broadcast Frames (AB) bit is deasserted. Frames that are

discarded from FIFO overflow are not counted.

Note: The per frame byte count does not include the VLAN TAG

and VID if the Enable VLAN Tag Stripping bit is set in the

Receive Filtering Engine Control Register (RFE_CTL). It

does not include the FCS if the FCS Stripping bit is set in

the MAC Receive Register (MAC_RX).

RX Multicast Byte Count Total number of bytes received from multicast frames without errors.

This counter does not count frames that fail address filtering. Pause

frames filtered by Forward Pause Frames (FPF) are not counted.

Frames that are discarded from FIFO overflow are not counted.

Note: The per frame byte count does not include the VLAN TAG

and VID if the Enable VLAN Tag Stripping bit is set in the

Receive Filtering Engine Control Register (RFE_CTL). It

does not include the FCS if the FCS Stripping bit is set in

the MAC Receive Register (MAC_RX).

RX Unicast Frames Number of unicast frames received without errors.

This counter does not count frames that fail address filtering. Pause

frames filtered by Forward Pause Frames (FPF) are not counted.

Frames that are discarded from FIFO overflow are not counted.

RX Broadcast Frames Number of broadcast frames received without errors.

This counter does not count broadcast frames received when the

Accept Broadcast Frames (AB) bit is deasserted. Frames that are

discarded from FIFO overflow are not counted.

RX Multicast Frames Number of multicast frames received without errors.

This counter does not count frames that fail address filtering. Pause

frames filtered by Forward Pause Frames (FPF) are not counted.

Frames that are discarded from FIFO overflow are not counted.

RX Pause Frames Number of pause frames received without errors.

Note: This counter records pause frames that failed address

filtering.

TABLE 5-9: STATISTICS COUNTER DEFINITIONS (CONTINUED)

Name Description Size

(Bits)

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 25

LAN7850

RX 64 Byte Frames Number of frames received with a length of 64 bytes without errors.

This counter does not count frames that fail address filtering. Pause

frames filtered by Forward Pause Frames (FPF) are not counted.

Frames that are discarded from FIFO overflow are not counted.

RX 65 - 127 Byte Frames Number of frames received with a length between 65 bytes and 127

bytes without errors.

This counter does not count frames that fail address filtering. Frames

that are discarded from FIFO overflow are not counted.

RX 128 - 255 Byte Frames Number of frames received with a length between 128 bytes and 255

bytes without errors.

This counter does not count frames that fail address filtering. Frames

that are discarded from FIFO overflow are not counted.

RX 256 - 511 Bytes Frames Number of frames received with a length between 256 bytes and 511

bytes without errors.

This counter does not count frames that fail address filtering. Frames

that are discarded from FIFO overflow are not counted.

RX 512 - 1023 Byte Frames Number of frames received with a length between 512 bytes and

1023 bytes without errors.

This counter does not count frames that fail address filtering. Frames

that are discarded from FIFO overflow are not counted.

RX 1024 - 1518 Byte Frames Number of frames received with a length between 1024 bytes and

1518 bytes without errors.

This counter does not count frames that fail address filtering. Frames

that are discarded from FIFO overflow are not counted.

RX Greater 1518 Byte Frames Number of frames received with a length greater than 1518 bytes

without errors.

This counter does not count frames that fail address filtering. Frames

that are discarded from FIFO overflow are not counted.

EEE RX LPI Transitions Number of times that the LPI indication from the PHY changes from

de-asserted to asserted.

This counter is reset if Energy Efficient Ethernet Enable (EEEEN) in

MAC Control Register (MAC_CR) is low.

This counters is required to operate during SUSPEND0, SUSPEND3

and Normal Configured Power states.

EEE RX LPI Time The amount of time, in micro-seconds, that the PHY indicates LPI.

This counter is reset if Energy Efficient Ethernet Enable (EEEEN) in

MAC Control Register (MAC_CR) is low.

This counters is required to operate during SUSPEND0, SUSPEND3

and Normal Configured Power states.

TX FCS Errors Number of frames transmitted with an FCS error. The MAC can be

forced to transmit frames with FCS errors by setting the Bad FCS

(BFCS) bit.

TABLE 5-9: STATISTICS COUNTER DEFINITIONS (CONTINUED)

Name Description Size

(Bits)

LAN7850

DS00001993D-page 26  2015 - 2017 Microchip Technology Inc.

TX Excess Deferral Errors Number of frames that were excessively deferred. The frame has

been deferred for more than two max-sized frame times + 16 bytes.

The maximum frame length is defined by Maximum Frame Size

(MAX_SIZE) in MAC Receive Register (MAC_RX)

Note: Defer time is not cumulative. If the transmitter defers for

10,000 bit times, then transmits, collides, backs off, and

then has to defer again after completion of back-off, the

deferral timer resets to 0 and restarts.

Note: The 16 bytes of margin is to account for the possibility of

double VLAN tags.

TX Carrier Errors Number of frames that had a carrier sense error occur during

transmission. This error is caused by no carrier or loss of carrier.

TX Bad Byte Count Total number of bytes sent from errored transmissions. 32

TX Single Collisions Number of frames successfully transmitted after a single collision

occurs.

TX Multiple Collisions Number of frames successfully transmitted after multiple collisions

occur.

TX Excessive Collision Number of transmitted frames aborted due to excessive collisions.

Note: 16 collisions results in an excessive collisions.

TX Late Collisions Number of transmitted frames aborted because of a late collision. 20

TX Unicast Byte Count Total number of bytes transmitted by unicast frames without errors.

This counter does not count flow control frames. Bytes transmitted

as part of a partial packet transmission (half-duplex collision) are not

counted.

TX Broadcast Byte Count Total number of bytes transmitted by broadcast frames without

errors.

This counter does not count flow control frames. Bytes transmitted

as part of a partial packet transmission (half-duplex collision) are not

counted.

TX Multicast Byte Count Total number of bytes transmitted by multicast frames without errors.

This counter does not count flow control frames. Bytes transmitted

as part of a partial packet transmission (half-duplex collision) are not

counted.

TX Unicast Frames Number of unicast TX frames transmitted without errors.

This counter does not count flow control frames.

TX Broadcast Frames Number of broadcast TX frames transmitted without errors.

This counter does not count flow control frames.

TX Multicast Frames Number of multicast TX frames transmitted without errors.

This counter does not count flow control frames.

TX Pause Frames Number of successfully transmitted pause frames. 20

TABLE 5-9: STATISTICS COUNTER DEFINITIONS (CONTINUED)

Name Description Size

(Bits)

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 27

LAN7850

TX 64 Byte Frames Number of frames transmitted with a length of 64 bytes without error.

This counter does not count flow control frames. Frames transmitted

as part of a partial packet transmission (half-duplex collision) are not

counted.

TX 65 - 127 Byte Frames Number of frames transmitted with a length between 65 bytes and

127 bytes without error.

Frames transmitted as part of a partial packet transmission (half-

duplex collision) are not counted.

TX 128 - 255 Byte Frames Number of frames transmitted with a length between 128 bytes and

255 bytes without error.

Frames transmitted as part of a partial packet transmission (half-

duplex collision) are not counted.

TX 256 - 511 Bytes Frames Number of frames transmitted with a length between 256 bytes and

511 bytes without error.

Frames transmitted as part of a partial packet transmission (half-

duplex collision) are not counted.

TX 512 - 1023 Byte Frames Number of frames transmitted with a length between 512 bytes and

1023 bytes without error.

Frames transmitted as part of a partial packet transmission (half-

duplex collision) are not counted.

TX 1024 - 1518 Byte Frames Number of frames transmitted with a length between 1024 bytes and

1518 bytes without error.

Frames transmitted as part of a partial packet transmission (half-

duplex collision) are not counted.

TX Greater 1518 Byte Frames Number of frames transmitted with a length greater than 1518 bytes

without error.

Frames transmitted as part of a partial packet transmission (half-

duplex collision) are not counted.

EEE TX LPI Transitions Number of times that the LPI request to the PHY changes from de-

asserted to asserted.

This counter is reset if Energy Efficient Ethernet Enable (EEEEN) in

MAC Control Register (MAC_CR) is low.

This counter is required to operate during SUSPEND0, SUSPEND3

and Normal Configured Power states.

EEE TX LPI Time The amount of time, in microseconds, that the PHY is requested to

send LPI.

This counter is reset if Energy Efficient Ethernet Enable (EEEEN) in

MAC Control Register (MAC_CR) is low.

This counters is required to operate during SUSPEND0, SUSPEND3

and Normal Configured Power states.

TABLE 5-9: STATISTICS COUNTER DEFINITIONS (CONTINUED)

Name Description Size

(Bits)

LAN7850

DS00001993D-page 28  2015 - 2017 Microchip Technology Inc.

5.2.3 DESCRIPTOR RAM

The Control Endpoint manipulates an internal Descriptor RAM which stores various configuration for the device includ-

ing USB descriptors. The descriptor RAM is typically loaded from either an external EEPROM or the integrated OTP.

However a mechanism exists, EEPROM-less mode, which allows the host software to directly configure the Descriptor

RAM. It is described in Section 10.6, "Customized Operation Without EEPROM". The Descriptor RAM format is dis-

cussed in Section 10.6.3, "Descriptor RAM Initialization"

The Control EP first evaluates whether an external EEPROM is present by the successful recognition of the EEPROM

signature. If an EEPROM exists, it shall be used to load the contents into the Descriptor RAM.

If an EEPROM does not exist, the Control EP considers whether the OTP is configured. If the OTP is configured it shall

be used to load the Descriptor RAM.

In the event that the EEPROM does not exist and the OTP is not configured, the Control EP shall utilize the CSR and

EEPROM defaults, as defined in Section 10.5, "EEPROM Defaults", for configuring the device.

EEPROM-Less operation may be invoked by host software. This mode shall take priority over an external EEPROM or

configured OTP. This mode is described in Section 10.6, "Customized Operation Without EEPROM".

5.3 Bulk In Endpoint

The Bulk In Endpoint is controlled by the UTX (USB Bulk In Transmitter). The UTX is responsible for encapsulating

Ethernet data into USB Bulk In packets. Ethernet frames are retrieved from the FCT’s RX FIFO and passed to the UDC.

The UTX manages an 8 KB UTX FIFO Buffer. USB packets from FCT are temporarily stored there to facilitate efficient

bursting. In support for bursting, a USB Command FIFO is managed by the UTX to track packet lengths.

5.3.1 USB TX DATA FIFO

The UTX Data FIFO RAM is a 2K x 32 (8 KB) dual port type. All USB packets are DWORD aligned in the USB TX Data

FIFO. All Ethernet frames are DWORD aligned in USB packets. Within a USB transfer (assuming MEF mode is

enabled), consecutive Ethernet frames are not concatenated into the same DWORD. The unused bytes (up to 3) in the

DWORD at the end of an Ethernet frame (assuming it is not the last frame) are included in the USB packet and its length

and are discarded by the host driver software. At the end of a USB transfer, the unused bytes (up to 3) are not included

in the USB packet or it’s length. The USB Device Controller will discard any unused bytes within a DWORD.

5.3.2 USB TX COMMAND FIFO

As Ethernet frames are transferred into the USB TX Data FIFO, the resulting USB packet lengths (including any zero

length packets) are written into the USB TX Command FIFO. The USB Device Controller requires the packet lengths

and number of packets available at the start of a USB transmission.

The size of the USB command FIFO allows up to 32 packets to be queued. This number is based on the 8K byte size

of the USB TX Data FIFO divided by an average USB packet size of 256 bytes (e.g. 16 @ 512 byte packets and 16 zero

length packets, etc.). Since it is possible for the USB TX Command FIFO to fill before the USB TX Data FIFO, the USB

TX Command FIFO provides a full signal.

The head entry (USB packet length) and depth (number of entries) of the USB TX Command FIFO are passed as the

USB packet length and number of available packets, respectively, to the USB Device Controller.

5.3.3 MEF/SEF OPERATION

The UTX supports the following two modes of operation: MEF and SEF, selected via the Multiple Ethernet Frames per

USB Packet (MEF) bit of the Hardware Configuration Register (HW_CFG).

• MEF: Multiple Ethernet frames per Bulk In packet. This mode will maximize USB bus utilization by allowing multi-

ple Ethernet frames to be packed into a USB packet. Frames greater than maximum USB packet size are split

across multiple Bulk In packets.

• SEF: Single Ethernet frame per Bulk In packet. This mode will not maximize USB bus utilization, but simplifies the

host software implementation and can potentially ease the burden on a low end Host processor. Frames greater

than maximum USB packet size are split across multiple Bulk In packets.

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 29

LAN7850

Each Ethernet frame is pre-pended with three RX Command Words, RX Command A, RX Command B and RX Com-

mand C by the FCT. RX Command A contains the frame length that is used by the UTX to perform the encapsulation

functions. The contents of the command words are generated by the MAC, RFE, and FCT.

An Ethernet frame (starting with RX Command A) always begins on a DWORD boundary in the FCT. In MEF mode,

UTX will not concatenate the end of the current frame and the beginning of the next frame into the same DWORD.

Therefore, the last DWORD of an Ethernet frame may have unused bytes added to ensure DWORD alignment of the

RX Command A of the next frame. The addition of pad bytes at the end of the frame depends on whether another frame

is available for transmission after the current one. If the current frame is the last frame to be transmitted, no pad bytes

will be added, as the USB protocol allows for termination of the packet on a byte boundary. If, however, another frame

is available for transmission, the current frame will be padded out so that it ends on the DWORD boundary. This ensures

the next frame to be transmitted, starting with RX Command A, will start on a DWORD boundary.

Any unused bytes that were added to the last DWORD of a frame are not counted in the length field of RX Command A.

As noted in Section 5.3.1, UTX is responsible for storing USB packets into UTX Data FIFO. When calculating USB

packet lengths DWORD padding between Ethernet frames is included.

In accordance with the USB protocol, UTX terminates a burst with either a ZLP or a Bulk In packet with a size of less

than the Bulk In maximum packet size (512 for HS, 64 for FS). The ZLP is needed when the total amount of data trans-

mitted is a multiple of a Bulk In maximum packet size. UTX monitors the UTX Data FIFO size to determine when a burst

has ended.

The UTX monitors the RX FIFO size signal from the FCT and moves data into the UTX Data FIFO as complete Ethernet

frames are received by the FCT and space is available. When the frame is moved its length is incorporated to packet

length of the USB packet being formed. After a complete USB packet is created an entry is written into the UTX Com-

mand FIFO. If the Ethernet frame can not fit into the USB packet the remainder is moved into subsequent USB

packet(s).

The UTX provides a mechanism for limiting the size of the USB burst per the burst cap function as described in Section

, "Burst Cap Usage". This caps the amount of data that can be moved in a USB transfer before termination by a ZLP.

The burst cap function applies for all operating speeds.

FIGURE 5-1: MEF USB ENCAPSULATION

Note: In SEF mode, a ZLP is transmitted if the Ethernet frame is the same size as a maximum size Bulk In packet,

or a multiple of the maximum Bulk In packet size.

The Host ignores unused bytes that exist in the last DWORD of an Ethernet frame.

When using SEF mode, there will never be any unused bytes added for end alignment padding. The USB

transfer always ends on the last byte of the Ethernet frame.

If UTX receives a Bulk In token when the RX FIFO is empty, it will transmit a ZLP if Bulk-In Empty Response

(BIR) is set otherwise it will NAK (FS/HS) or NRDY (SS) when cleared.

LAN7850

DS00001993D-page 30  2015 - 2017 Microchip Technology Inc.

In order to more efficiently utilize USB bandwidth in MEF mode, the UTX has a mechanism for delaying the transmission

of a short packet, or ZLP. This mode entails having the UTX wait a time defined by the Bulk-In Delay Register

(BULK_IN_DLY) before terminating the burst. A value of zero in this register disables this feature. By default, a delay of

34 us is used.

After UTX transmits the last USB bMaxPacketSize packet in a burst, UTX enables an internal timer. When this timer is

equal to Bulk In Delay, any Bulk In data in the UTX Data FIFO is transmitted upon next opportunity to the host.

In HS/FS mode, if enough data arrives before the timer elapses to build at least one maximum sized packet, then the

UTX will transmit this packet when it receives the next Bulk In Token. After packet transmission, the UTX will reset its

internal timer and delay the short packet, or ZLP, transmission until the Bulk In Delay time elapses or new data is

received per above.

In the case where the UTX Data FIFO is empty and a single Ethernet packet less than USB bMaxPacketSize is then

received, the UTX enables its internal timer. If enough data arrives before the timer elapses to build at least one maxi-

mum sized packet, the UTX will transmit this packet and reset the timer. Otherwise, FIFO data is sent after the timer

expires.

In HS/FS mode, the UTX will NAK any Bulk In tokens while waiting for new data and Bulk In Delay to elapse.

Bulk In Delay is only intended for MEF operation and not appropriate for SEF mode.

5.3.4 USB ACKS AND RETRIES

In the case of an error condition, the UTX will issue a rewind to the FCT. This occurs when the UTX completes trans-

mitting a Bulk In packet and does not receive an ACK from the Host. In this case, the next frame received by the UTX

will be another In token and the Bulk In packet is retransmitted. When the ACK is finally received, the UTX notifies the

FCT. The FCT will then advance the read head pointer to the next packet.

Both the USB TX Data and Command FIFOs handle USB retries. When a USB packet is acknowledged, its command

information is popped from the USB TX Command FIFO and its storage can be release from the USB TX Data FIFO

(note that zero length packets would not release any USB TX Data FIFO space).

Burst Cap Usage

The UTX, via the Burst Cap Register (BURST_CAP), is capable of prematurely terminating a burst. The Burst Cap Reg-

ister (BURST_CAP) uses units of USB packet size (64/512/1024 bytes). To enable use of the Burst Cap register, the

Burst Cap Enable (BCE) bit in the USB Configuration Register 0 (USB_CFG0) must be set.

For proper operation, the BURST_CAP field should be set by software so that the following relationships hold true:

For HS Operation, BURST_CAP * 512 >= Maximum Frame Size (MAX_SIZE)

For FS Operation, BURST_CAP * 64 >= Maximum Frame Size (MAX_SIZE)

Failure to set BURST_CAP values that obey the previous rules may result in untoward operation and may yield unpre-

dictable results.

Whenever Burst Cap enforcement is disabled and the RX FIFO, and UTX FIFO, are empty, the UTX will respond with

a ZLP if Bulk-In Empty Response (BIR) = “0”. However, it will respond with NAK (FS/HS) when Bulk-In Empty Response

(BIR) = “1”.

Whenever Burst Cap enforcement is enabled, the following holds:

• For HS Operation:

BURSTMax = BURST_CAP * 512

• For FS operation:

BURSTMax = BURST_CAP * 64

Let BURSTCur = Length of current burst = Summation of the lengths of frames in the current burst.

Let LENGTHNext = Length of the next frame available in the RX FIFO.

If the RX FIFO runs out of data, or a frame is available and BURSTCur + LENGTHNext > BURSTMax, then the burst is

terminated with either a short USB packet or with a ZLP.

Otherwise, the next frame is able to fit in the current burst without exceeding BURST_CAP. The burst is continued and

BURSTCur is incremented by LENGTHNext.

Note: The first Ethernet frame of the burst is always sent without checking if it exceeds BURST_CAP.

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 31

LAN7850

5.4 Bulk Out Endpoint

The Bulk Out Endpoint is controlled by the URX (USB Bulk Out Receiver). URX is responsible for receiving Ethernet

data encapsulated over USB Bulk Out packet(s). Unlike the UTX, the URX does not explicitly track Ethernet frames. It

views all received packets purely as USB data. The extraction of Ethernet frames is handled by the FCT. The URX

always simultaneously supports MEF and SEF modes.

5.4.1 USB RX DATA FIFO

The URX manages an 8 KB Data FIFO. All USB packets start on DWORD boundaries. The format of the data within

USB packets and across USB transactions ensures that Ethernet frames (including command headers) are DWORD

aligned. Padding between Ethernet frames is added by the host driver and stripped by the TX FIFO.

5.4.2 RETRIES AND ERRORS

Packets from the USB Device Controller have the possibility of an error and subsequent retry. Based on the status of

the packet, the packet may be either rejected or accepted. If the packet is rejected, the write pointers and free space is

recovered from the data FIFO. If the packet is accepted, it can be made available to the FCT. Packet rejection or accep-

tance will occur before the start of the next packet, such that multiple outstanding packets need not be tracked.

The FCT notifies the URX when it detects loss of sync. When this occurs, the URX stalls the Bulk Out pipe via the UDC.

This is an appropriate response, as loss of sync is a catastrophic error (which can only be caused by a host software

error. See Section 6.2.4, "TX Error Detection"). This behavior is configurable via the Stall Bulk-Out Pipe Disable (SBP)

bit in the USB Configuration Register 0 (USB_CFG0).

5.5 Interrupt Endpoint

The Interrupt endpoint is responsible for indicating the device’s status at each polling interval. The Interrupt endpoint is

implemented via the CTL module. When the endpoint is accessed the following fields are presented to the host.

Note: If Store Bad Frames is set in the FIFO Controller RX FIFO Control Register (FCT_RX_CTL), then the size

of the transmitted burst may exceed the value specified by BURST_CAP. This can happen if an oversized

frame is received that is larger than BURST_CAP.

Ethernet frames are not fragmented across bursts when using Burst Cap Enforcement.

LAN7850

DS00001993D-page 32  2015 - 2017 Microchip Technology Inc.

5.5.1 INTERRUPT PACKET FORMAT

If there is no interrupt status to report the device responds with a NAK unless Interrupt Endpoint Always On (INTEP_ON)

in Interrupt Endpoint Control Register (INT_EP_CTL) is set in which case an interrupt packet of 0x0 is returned.

For an interrupt event to be reported via the Interrupt endpoint, the respective bit must be enabled in Interrupt Endpoint

Control Register (INT_EP_CTL). The interrupt status can be cleared by writing to the Interrupt Status Register

(INT_STS).

5.5.2 USB STATUS

USB_STS_INT bit is used to facilitate communication with the host software regarding OS programming of the device.

The following are tracked by this mechanism.

• SET Select (SET_SEL) command issued

• Function Remote Wakeup Status

• Device Remote Wakeup Status

TABLE 5-10: INTERRUPT PACKET FORMAT

Bits Description

31:29 Reserved

28 OTP_WR_DONE_INT

27 Reserved

26 EEE_START_TX_LPI_INT

25 EEE_STOP_TX_LPI_INT

24 EEE_RX_LPI_INT

23 MACRTO_INT

22 RDFO_INT

21 TXE_INT

20 USB_STS_INT

19 TX_DIS_INT

18 RX_DIS_INT

17 PHY_INT

16 DP_INT

15 MAC_ERR_INT

14 TDFU

13 TDFO

12 UTX_FP

11:0 GPIOx_INT

Note: The polling interval is static and set through OTP or EEPROM. The polling interval can be changed by the

host updating the contents of the EEPROM and resetting the part.

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 33

LAN7850

The USB Status Register (USB_STATUS) includes both status change bits as well as the current value of the respective

when appropriate.

APPLICATION NOTE: The majority of the above status information can also be obtained using the GET_STATUS

USB request.

5.6 LPM Support

The USB device controller supports Link Power Management (LPM). It is fully capable of responding to LPM devices

and placing the device into the L1 and L2 states or conversely moving the device to L0 via remote wakeup or Resume

signaling.

Further details on LPM implementation can be found in Section 13.0, "Clocks and Power management (CPM)," on

page 126.

LPM is enabled by setting the LPM Capability (LPM_CAP) bit in USB Configuration Register 0 (USB_CFG0).

5.6.1 LPM L1

In L1 minimal components are powered down in order to ensure the device can quickly transition to L0 and not violate

the pertinent USB specification parameters.

The device shall automatically transition the link from L1 to L0 after it receives a frame which passes any programmed

filters in the RFE and MAC. Additionally, a scheduled interrupt EP packet shall also cause the device to transition out of

L0.

5.6.2 LPM L2

The L2 state mimics the respective suspend mode programmed in the Suspend Mode (SUSPEND_MODE) of the Power

Management Control Register (PMT_CTL).

5.7 USB Descriptors

In the event that the OTP is not configured or an external EEPROM is not available, the default values defined in the

descriptor tables below are used - except in the case where EEPROM-less mode is enabled. In that case, the descrip-

tors are programmed as defined in Section 10.6, "Customized Operation Without EEPROM".

LAN7850

DS00001993D-page 34  2015 - 2017 Microchip Technology Inc.

5.7.1 DEVICE DESCRIPTOR

The Device Descriptors are initialized based on values stored in OTP or EEPROM. Table 5-11 shows the default Device

Descriptor values. These values are used for Full-Speed and High-Speed operation.

Note 5-1 The descriptor length and descriptor type for Device Descriptors specified in OTP or EEPROM are

“don’t cares” and are always overwritten by hardware as 0x12 and 0x01, respectively.

Note 5-2 When operating in USB 2.0 mode the default value is 0210h (USB 2.10).

Note 5-3 When operating in full-speed or high-speed mode it should be set to 40h. If the OTP is not configured,

or EEPROM is not present, the aforementioned values are returned.

Note 5-4 Default value is dependent on device release. The MSB matches the device release and the LSB is

hard-coded to 00h. The initial release value is 01h. Subsequent versions will increment the value.

Note 5-5 Value is loaded from OTP, or EEPROM, but must be equal to the Default Value in order to comply

with the USB Specification and provide for normal device operation. Specification of any other value

will result in unwanted behavior and untoward operation.

TABLE 5-11: DEVICE DESCRIPTOR

OFFSET FIELD SIZE

(BYTES) DEFAULT

VALUE

LOADED

FROM

EEPROM/

OTP DESCRIPTION

00h bLength 1 12h Note 5-1 Size of the Descriptor in Bytes (18

bytes)

01h bDescriptorType 1 01h Note 5-1 Device Descriptor (0x01)

02h bcdUSB 2 Note 5-2 Yes USB Specification Number which

device complies to

04h bDeviceClass 1 FFh Yes Class Code

05h bDeviceSubClass 1 00h Yes Subclass Code

06h bDeviceProtocol 1 FFh Yes Protocol Code

07h bMaxPacketSize 1 Note 5-3 Yes Maximum Packet Size for Endpoint 0

08h IdVendor 2 0424h Yes Vendor ID

0Ah IdProduct 2 7850h Yes Product ID

0Ch bcdDevice 2 Note 5-4 Yes Device Release Number

0Eh iManufacturer 1 00h Yes Index of Manufacturer String

Descriptor

0Fh iProduct 1 00h Yes Index of Product String Descriptor

10h iSerialNumber 1 00h Yes Index of Serial Number String

Descriptor

11h bNumConfigurations 1 01h Note 5-5 Number of Possible Configurations

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 35

LAN7850

5.7.2 CONFIGURATION DESCRIPTOR

The Configuration Descriptor is initialized based on values stored in OTP or EEPROM. Table 5-12 shows the default

Configuration Descriptor values. These values are used for Full-Speed and High-Speed operation.

Note 5-6 Value is loaded from OTP, or EEPROM, but must be equal to the Default Value in order to provide

for normal device operation. Specification of any other value will result in unwanted behavior and

untoward operation.

Note 5-7 The descriptor type for Configuration Descriptors specified in OTP, or EEPROM, is a “don’t care” and

is always overwritten by hardware as 0x02.

Note 5-8 Default value is 0027h (39 bytes) when operating in USB 2.0 mode.

Note 5-9 Default value is 01h in Self Powered mode. In Bus Powered mode, default value is FAh (500mA).

TABLE 5-12: CONFIGURATION DESCRIPTOR

OFFSET FIELD SIZE

(BYTES) DEFAULT

VALUE

LOADED

FROM

EEPROM/

OTP DESCRIPTION

00h bLength 1 09h Note 5-6 Size of the Configuration Descriptor

in bytes (9 bytes)

01h bDescriptorType 1 02h Note 5-7 Configuration Descriptor (0x02)

02h wTotalLength 2 Note 5-8 Note 5-6 Total length in bytes of data returned

04h bNumInterfaces 1 01h Note 5-6 Number of Interfaces

05h bConfigurationValue 1 01h Note 5-6 Value to use as an argument to select

this configuration

06h iConfiguration 1 00h Yes Index of String Descriptor describing

this configuration

07h bmAttributes 1 E0h Yes Self powered and remote wakeup

enabled.

08h bMaxPower 1 Note 5-9 Yes Maximum Power Consumption

Note: The Configuration Flags of the OTP, or EEPROM, may affect the default value of bmAttributes.

LAN7850

DS00001993D-page 36  2015 - 2017 Microchip Technology Inc.

5.7.3 INTERFACE DESCRIPTOR DEFAULT

Table 5-13 shows the default value for Interface Descriptor 0. This descriptor is initialized based on values stored in OTP

or EEPROM.

Note 5-10 Value is loaded from OTP or EEPROM, but must be equal to the Default Value in order to comply

with the USB Specification and provide for normal device operation. Specification of any other value

will result in unwanted behavior and untoward operation.

5.7.4 ENDPOINT 1 DESCRIPTOR (BULK-IN)

Table 5-14 shows the default value for Endpoint Descriptor 1. This descriptor is not initialized from values stored in OTP

or EEPROM.

Note 5-11 64 bytes for full-speed mode, 512 bytes for high-speed mode.

TABLE 5-13: INTERFACE DESCRIPTOR 0

OFFSET FIELD SIZE

(BYTES) DEFAULT

VALUE

LOADED

FROM

EEPROM/

OTP DESCRIPTION

00h bLength 1 09h Note 5-10 Size of Descriptor in Bytes (9 Bytes

01h bDescriptorType 1 04h Note 5-10 Interface Descriptor (0x04)

02h bInterfaceNumber 1 00h Note 5-10 Number identifying this Interface

03h bAlternateSetting 1 00h Note 5-10 Value used to select alternative

setting

04h bNumEndpoints 1 03h Note 5-10 Number of Endpoints used for this

interface (Less endpoint 0)

05h bInterfaceClass 1 FFh Yes Class Code

06h bInterfaceSubClass 1 00h Yes Subclass Code

07h bInterfaceProtocol 1 FFh Yes Protocol Code

08h iInterface 1 00h Yes Index of String Descriptor Describing

this interface

TABLE 5-14: ENDPOINT 1 DESCRIPTOR

OFFSET FIELD SIZE

(BYTES) DEFAULT

VALUE

LOADED

FROM

EEPROM DESCRIPTION

00h bLength 1 07h No Size of Descriptor in bytes

01h bDescriptorType 1 05h No Endpoint Descriptor

02h bEndpointAddress 1 81h No Endpoint Address

03h bmAttributes 1 02h No Bulk Transfer Type

04h wMaxPacketSize 2 Note 5-11 No Maximum Packet Size this endpoint

is capable of sending.

06h bInterval 1 00h No Interval for polling endpoint data

transfers. Ignored for bulk endpoints.

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 37

LAN7850

5.7.5 ENDPOINT 2 DESCRIPTOR (BULK-OUT)

Table 5-14 shows the default value for Endpoint Descriptor 2. This descriptor is not initialized from values stored in OTP

or EEPROM.

Note 5-12 64 bytes for full-speed mode, 512 bytes for high-speed mode

5.7.6 ENDPOINT 3 DESCRIPTOR (INTERRUPT)

Table 5-16 shows the default value for Endpoint Descriptor 3. Only the bInterval field of this descriptor is initialized from

OTP or EEPROM.

Note 5-13 This value is loaded from OTP, or EEPROM. A full-speed and high-speed polling interval exists. If

OTP is not configured, and EEPROM does not exist, then this value defaults to 04h for HS, 01h for

FS.

TABLE 5-15: ENDPOINT 1 DESCRIPTOR

OFFSET FIELD SIZE

(BYTES) DEFAULT

VALUE

LOADED

FROM

EEPROM/

OTP DESCRIPTION

00h bLength 1 07h No Size of Descriptor in bytes

01h bDescriptorType 1 05h No Endpoint Descriptor

02h bEndpointAddress 1 02h No Endpoint Address

03h bmAttributes 1 02h No Bulk Transfer Type

04h wMaxPacketSize 2 Note 5-12 No Maximum Packet Size this endpoint

is capable of sending.

06h bInterval 1 00h No Interval for polling endpoint data

transfers. Ignored for bulk endpoints.

TABLE 5-16: ENDPOINT 2 DESCRIPTOR

OFFSET FIELD SIZE

(BYTES) DEFAULT

VALUE

LOADED

FROM

EEPROM/

OTP DESCRIPTION

00h bLength 1 07h No Size of Descriptor in bytes

01h bDescriptorType 1 05h No Endpoint Descriptor

02h bEndpointAddress 1 83h No Endpoint Address

03h bmAttributes 1 03h No Interrupt Transfer Type

04h wMaxPacketSize 2 10h No Maximum Packet Size this endpoint

is capable of sending.

06h bInterval 1 Note 5-13 Yes Interval for polling endpoint data

transfers.

LAN7850

DS00001993D-page 38  2015 - 2017 Microchip Technology Inc.

5.7.7 OTHER SPEED CONFIGURATION DESCRIPTOR

The fields in this descriptor are derived from Configuration Descriptor information that is stored in OTP or EEPROM.

Note 5-14 Value is loaded from OTP or EEPROM, but must be equal to the Default Value in order to comply

with the USB 2.x Specification and provide for normal device operation. Specification of any other

value will result in unwanted behavior and untoward operation.

Note 5-15 Default value is 01h in Self Powered mode and FAh (500 mA) in Bus Powered mode.

TABLE 5-17: OTHER SPEED CONFIGURATION DESCRIPTOR

OFFSET FIELD SIZE

(BYTES) DEFAULT

VALUE

LOADED

FROM

EEPROM/

OTP DESCRIPTION

00h bLength 1 09h Note 5-14 Size of Descriptor in bytes (9 bytes)

01h bDescriptorType 1 07h No Other Speed Configuration Descriptor

(0x07)

02h wTotalLength 2 0027h Note 5-14 Total length in bytes of data returned

(39 bytes)

04h bNumInterfaces 1 01h Note 5-14 Number of Interfaces

05h bConfigurationValue 1 01h Note 5-14 Value to use as an argument to select

this configuration

06h iConfiguration 1 00h Yes Index of String Descriptor describing

this configuration

07h bmAttributes 1 E0h Yes Bus powered and remote wakeup

enabled.

08h bMaxPower 1 Note 5-15 Yes Maximum Power Consumption

Note: OTP or EEPROM values are obtained for the Configuration Descriptor at the other USB speed. I.e., if the

current operating speed is FS, then the HS Configuration Descriptor values are used, and vice-versa.

The Configuration Flags of the OTP, or EEPROM, may affect the default value of bmAttributes

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 39

LAN7850

5.7.8 DEVICE QUALIFIER DESCRIPTOR

The fields in this descriptor are derived from Device Descriptor information that is stored in the OTP or EEPROM.

Note 5-16 .Value is loaded from OTP or EEPROM, but must be equal to the Default Value in order to comply

with the USB 2.x Specification and provide for normal device operation.

TABLE 5-18: DEVICE QUALIFIER DESCRIPTOR

OFFSET FIELD SIZE

(BYTES) DEFAULT

VALUE

LOADED

FROM

EEPROM/

OTP DESCRIPTION

00h bLength 1 0Ah No Size of Descriptor in bytes (10 bytes)

01h bDescriptorType 1 06h No Device Qualifier Descriptor (0x06)

02h bcdUSB 2 0210h Yes USB Specification Number which

device complies to.

04h bDeviceClass 1 FFh Yes Class Code

05h bDeviceSubClass 1 00h Yes Subclass Code

06h bDeviceProtocol 1 FFh Yes Protocol Code

07h bMaxPacketSize0 1 40h Note 5-16 Maximum Packet Size

08h bNumConfigurations 1 01h Note 5-16 Number of Other-Speed

Configurations

09h Reserved 1 00h No Must be zero

Note: OTP or EEPROM values are from the Device Descriptor (including any EEPROM override) at the opposite

HS/FS operating speed. I.e., if the current operating speed is HS, then Device Qualifier data is based on

the FS Device Descriptor, and vice-versa.

LAN7850

DS00001993D-page 40  2015 - 2017 Microchip Technology Inc.

5.7.9 STRING DESCRIPTORS

5.7.9.1 String Index = 0 (LANGID)

5.7.9.2 String Indices 1-5

The device returns whatever bytes are in the designated OTP or EEPROM area for each of these strings. It is the

responsibility of the OTP or EEPROM programmer to correctly set the bLength and bDescriptorType fields in the

descriptor consistent with the byte length specified in the corresponding EEPROM locations.

TABLE 5-19: LANGID STRING DESCRIPTOR

OFFSET FIELD SIZE

(BYTES) DEFAULT

VALUE

LOADED

FROM

EEPROM/

OTP DESCRIPTION

00h bLength 1 04h No Size of LANGID Descriptor in bytes (4

bytes)

01h bDescriptorType 1 03h No String Descriptor (0x03)

02h LANGID 2 None Yes Must be set to 0x0409 (US English).

Note: If there is no valid/enabled OTP or EEPROM, or if all string lengths in the OTP or EEPROM are 0, then

there are no strings, so any Host attempt to read the LANGID string will return stall in the Data Stage of the

Control Transfer.

If there is a valid/enabled OTP or EEPROM, and if at least one of the string lengths is not 0, then the value

contained at addresses 0x23-0x24 shall be returned. These must be 0x0409 to allow for proper device

operation.

Note: The device ignores the LANGID field in Control Read’s of Strings, and will return the String (if it exists),

regardless of whether the requested LANGID is 0x0409 or not.

Table 0.1 String Descriptor (Indices 1-5)

OFFSET FIELD SIZE

(BYTES) DEFAULT

VALUE

LOADED

FROM

EEPROM/

OTP DESCRIPTION

00h bLength 1 none Yes Size of the String Descriptor in bytes

01h bDescriptorType 1 none Yes String Descriptor (0x03)

02h Unicode String 2*N none Yes 2 bytes per unicode character, no

trailing NULL.

Note: If there is no valid/enabled OTP or EEPROM, or if the corresponding String Length and offset for a given

string index is zero, then that string does not exist, so any Host attempt to read that string will return stall

in the Data Stage of the Control Transfer.

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 41

LAN7850

5.7.10 BINARY DEVICE OBJECT STORE DESCRIPTOR

The Binary Device Object Store Descriptor is initialized based on values stored in OTP or EEPROM. Table 5-20 shows

the default Binary Device Object Store Descriptor values.

Note 5-17 The descriptor length and descriptor type for Binary Device Object Store Descriptors specified in OTP

or EEPROM are “don’t cares” and are always overwritten by hardware as 0x05 and 0x0F,

respectively.

5.7.11 USB 2.0 EXTENSION DESCRIPTOR

The USB 2.0 Extension Descriptor is initialized based on values stored in EEPROM. Table 5-21 shows the default USB

2.0 Extension Descriptor values.

TABLE 5-20: BINARY DEVICE OBJECT STORE DESCRIPTOR

OFFSET FIELD SIZE

(BYTES) DEFAULT

VALUE

LOADED

FROM

EEPROM/

OTP DESCRIPTION

00h bLength 1 05h Note 5-17 Size of Descriptor in bytes (5 bytes)

01h bDescriptorType 1 0Fh Note 5-17 BOS Descriptor (0x0F)

02h wTotalLength 2 0016h Yes Total length of this descriptor and its

sub-descriptors. (22 bytes)

04h bNumDeviceCaps 1 02h Yes Number of Device Capability

Descriptors in this BOS.

TABLE 5-21: USB 2.0 EXTENSION DESCRIPTOR

OFFSET FIELD SIZE

(BYTES) DEFAULT

VALUE

LOADED

FROM

EEPROM/

OTP DESCRIPTION

00h bLength 1 07h Note 5-18 Size of Descriptor in bytes (7 bytes)

01h bDescriptorType 1 10h Note 5-18 Device Capability Descriptor (0x10)

02h bDevCapabilityType 1 02h Note 5-18 USB 2.0 Extension Capability (0x02)

LAN7850

DS00001993D-page 42  2015 - 2017 Microchip Technology Inc.

Note 5-18 The descriptor length, descriptor type, and device capability type for USB 2.0 Extension Descriptors

specified in OTP or EEPROM are “don’t cares” and are always overwritten by hardware as 0x07,

0x10, and 0x02, respectively.

Note 5-19 The value of this bit must match that of the LPM Capable (CFG0_LPM_CAPABLE) flag contained in

Configuration Flags 0 of the OTP or EEPROM, if present. If the bit values disagree, unexpected

results and untoward operation may result.

03h bmAttributes 4 0006h Yes Bitmap encoding of number of

supported device level features. A

value of 1 in a bit location indicates a

feature is supported. A value of 0

indicates it is not supported.

Encodings are:

TABLE 5-21: USB 2.0 EXTENSION DESCRIPTOR (CONTINUED)

OFFSET FIELD SIZE

(BYTES) DEFAULT

VALUE

LOADED

FROM

EEPROM/

OTP DESCRIPTION

BIT ENCODING

31:16 RESERVED (0)

15:12 Recommended Deep BESL

value. Field shall be ignored

by system software if bit[4]

is zero.

11:8 Recommended Baseline

BESL value. Field shall be

ignored by system software

if bit[3] is zero.

4 Recommended deep BESL

valid.

3 Recommended baseline

BESL valid.

2 BESL & Alternate HIRD

definitions supported. The

LPM bit must be set to a

one when this bit is a one.

1 (LPM) Note 5-19

A value of 1 in this bit

position indicates that this

device supports the Link

Power Management

protocol.

0 RESERVED (0)

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 43

LAN7850

6.0 FIFO CONTROLLER (FCT)

The FIFO controller uses internal RAMs to buffer RX and TX traffic. Bulk-Out packets from the URX are directly stored

into the FCT TX FIFO. The FCT is responsible for extracting Ethernet frames from the USB packet data and passing

the frames to the MAC.

Received Ethernet Frames are stored into the FCT RX FIFO and become the basis for bulk-in packets. The FCT passes

the stored data to the UTX in blocks typically 1024, 512 or 64 bytes in size, depending on the current USB operating

speed.

6.1 RX Path (Ethernet to USB)

The 12 KB RX FIFO buffers Ethernet frames received from the RFE. The UTX extracts these frames from the FCT to

form USB Bulk In packets. Host software will ultimately reassemble the Ethernet frames from the USB packets.

FCT manages the writing of data into the RX FIFO through the use of two pointers - the rx_wr_ptr and the rx_wr_hd_ptr.

The rx_wr_ptr is used to write Ethernet frame data into the FIFO. The rx_wr_hd_ptr points to two locations prior to the

first FIFO location that holds frame data. The two DWORD space is used to write RX Command A and RX Command

B upon completion of frame reception. Additionally, each Ethernet frame includes RX Command C which resides in the

same DWORD that includes the first two bytes of frame data. The command words include information about the frame

and status provided by the MAC, RFE, and FCT.

The rx_rd_ptr is used for reading data from the FIFO and passing it to the UTX. In order to support rewinds, the rx_rd_h-

d_ptr exists, as discussed in Section 6.1.1, "RX Error Detection". After an Ethernet frame is successfully read from the

FIFO, the rx_rd_hd_ptr advances to point to the start of the next frame. Figure 6-1 illustrates how a frame is stored in

the FIFO, along with pointer usage.

When the RFE signals that it has Data ready, the RFE controller starts passing the RX packet data to the FCT. The FCT

updates the RX FIFO pointers as the data is written into the FIFO. The last information written into the FIFO are the

Command Words.

The RX FCT operates in store and forward mode. A received Ethernet frame is not visible to the UTX until the complete

frame, including the Command Words, has been written into the RX FIFO. This is due to the fact that the frame may

have to be removed via a rewind (pointer adjustment), in case of an error. Such is the case when a FIFO overflow con-

dition is detected as the frame is being received. The FCT may be configured to discard errored frames and filtered

frames through the use of a rewind operation. The automatic discard of errored and filtered frames is enabled/disabled

by the Store Bad Frames bit of the FIFO Controller RX FIFO Control Register (FCT_RX_CTL). Please refer to Section

6.1.1, "RX Error Detection," on page 44 for further details concerning errors which may result in the FCT performing

rewind operation.

The FCT provides the UTX with an indication of how much data is available in the RX FIFO. This information is reflected

in the FIFO Controller RX FIFO Control Register (FCT_RX_CTL). In addition, internal signaling is used to inform the

UTX that at least one entire frame has been received.

A RX FIFO overflow condition may be signaled via the RX Data FIFO Overflow Interrupt (RDFO_INT). The FCT RX

Overflow bit of the FIFO Controller RX FIFO Control Register (FCT_RX_CTL) is also asserted when an overflow has

occurred.

Note: RX Command C also serves the purpose of DWORD aligning the Ethernet frame TCP, IP and other proto-

col headers.

LAN7850

DS00001993D-page 44  2015 - 2017 Microchip Technology Inc.

6.1.1 RX ERROR DETECTION

The FCT can be configured to drop Ethernet frames when certain error conditions occur. The setting of the Store Bad

Frames bit of the FIFO Controller RX FIFO Control Register (FCT_RX_CTL) determines if the frame will be retained or

dropped. Error conditions are indicated in RX Command A. Please refer to Table 5-9, “Statistics Counter Definitions,”

on page 23 for more details on the error conditions tracked by the device.

FIGURE 6-1: RX FIFO STORAGE

Note: The disposition of frames having checksum errors (IP/TCP/UDP) is not affected by Store Bad Frames.

These frames are always passed to the Host Controller.

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 45

LAN7850

The FCT also drops frames when it detects a FIFO overflow condition. This occurs when the FIFO full condition occurs

while a frame is being received. The FCT also maintains a count of the number of times a FIFO overflow condition has

occurred.

Dropping an Ethernet frame is implemented by rewinding the received frame. A write side rewind is implemented by

setting the rx_wr_ptr to be equal to the rx_wr_hd_ptr. Similarly, a read side rewind is implemented by setting the

rx_rd_ptr to be equal to the rx_rd_hd_ptr.

For the case where the frame is dropped due to overflow, the FCT ignores the remainder of the frame. It will not begin

writing into the RX FIFO again until the next frame is received.

In the read direction, the FCT also supports rewinds for the UTX. This is needed for the case where the USB Bulk Out

packet is not successfully received by the Host and needs to be retransmitted.

6.1.2 RX COMMAND FORMAT

Every received Ethernet frame has Command Words concatenated to it that provide information about the frame.

Table 6-1, "RX Command A", Table 6-2, "RX Command B" and Table 6-3, "RX Command C" define the contents of the

Command Words.

RX Command A contains the frame length and has various status bits in regards to the frame. RX Command B provides

the raw layer 3 checksum if enabled and the VLAN tag, if applicable. The raw checksum can be used to assist in the

verification of checksums in unsupported layer 3 protocols. RX Command C provides additional information required for

wakeup support.

TABLE 6-1: RX COMMAND A

BITS SYMBOL DESCRIPTION

31 ICE IP Checksum Error

When set, this bit indicates an error was detected in the IP checksum.

Note: This field does not apply for IPv6 packets.

30 TCE TCP/UDP/ICMP/IGMP Checksum Error

When set, this bit indicates an error was detected in the TCP, UDP, ICMP or IGMP

checksum.

29 IPV IP Version

When set, indicates the frame contains an IPv6 packet. Otherwise, the frame

contains an IPv4 packet.

Note: This field is not valid if the Protocol ID is set to 00b.

28:27 PID Protocol ID

Indicates the L3/L4 protocol of the received packet.

00b - None IP

01b - TCP and IP

10b - UDP and IP

11b - IP

Note: 11b shall be used for ICMP and IGMP packets.

26 PFF Perfect Filter Passed

When set, this bit indicates the frame passed a perfect filter match of the MAC

destination address. If this bit is not set, then the frame was passed due to the hash

filter and needs to be further analyzed by the Host.

25 BAM Broadcast Frame

When set, this bit indicates that the received frame has a Broadcast address.

Note: If the destination MAC address is 0xFFFF_FFFF_FFFF then the address is

broadcast.

LAN7850

DS00001993D-page 46  2015 - 2017 Microchip Technology Inc.

24 MAM Multicast Frame

When set, this bit indicates that the received frame has a Multicast address.

Note: If the least significant bit of the most significant byte of the destination MAC

address is 1b, then the address is multicast. This bit is not set for a

broadcast address.

23 FVTG Frame is VLAN tagged

When set, this bit indicates a VLAN tag was extracted from the frame. The tag is

stored in the VLAN Tag field of RX Command B.

22 RED Receive Error Detected

When set, this bit indicates that an error was found in the received frame. One or

more of the following fields will be set: FCS, ALN, RXE, LONG, RUNT, RWT, ICE,

TCE.

21 RWT Receive Watchdog Timer Expired

When set, this bit indicates the received frame was longer than 11,264 bytes and was

truncated by the MAC.

20 RUNT Short/Runt Frame

When set, this bit indicates that frame was prematurely terminated before the collision

window (64 bytes). Runt frames are passed on to the Host only if the Store Bad

Frames bit is set in the FIFO Controller RX FIFO Control Register (FCT_RX_CTL).

This bit is also set when a short frame has been received.

19 LONG Frame Too Long

When set, this bit indicates that the frame length exceeds the size specified in the

Maximum Frame Size (MAX_SIZE) field of the MAC Receive Register (MAC_RX).

This is only a frame too long indication and will not cause the frame reception to be

truncated.

18 RXE RX Error

When set, this bit indicates that a receive error (internal PHY RX error signal

asserted) was detected during frame reception.

17 ALN Alignment Error

When set, this bit indicates that the frame contained a non-integer multiple of 8 bits

and the frame had an FCS Error.

Note: Valid only for 10/100 mode.

16 FCS FCS Error

When set, this bit indicates that a FCS error was detected. This bit is also set when

the internal PHY RX error signal is asserted during the reception of a frame even

though the FCS may be correct. This bit is not valid if the received frame is a Runt

frame or the Receive Watchdog Timer Expired.

15 UAM Unicast Frame

When set, this bit indicates that the received frame has a Unicast address.

14 ICSM Ignore TCP/UDP/ICMP/IGMP Checksum

When set, this bit indicates that the hardware was unable to calculate a UDP, TCP,

ICMP or IGMP checksum for the packet. This implies that the value of TCE is “don’t

care”.

13:0 LEN Frame Length

The size, in bytes, of the corresponding received frame. Size of the frame received

from the network.

Note: If the FCS Stripping bit of the MAC Receive Register (MAC_RX) is enabled,

this value is decremented by four bytes.

TABLE 6-1: RX COMMAND A (CONTINUED)

BITS SYMBOL DESCRIPTION

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 47

LAN7850

APPLICATION NOTE: It is possible for a received wakeup frame to cause a USB remote wakeup but not pass the

filtering rules programmed in the RFE. In order to obviate the need for system software to

implement the RFE filtering rules on a received wakeup frame, the RFE Filter Fail bit has

been provided. This serves as an additional condition for dropping a frame such as ICE or

TCE in RX Command A.

APPLICATION NOTE: Due to race conditions relating to when the device suspends relative to the reception of

received data frames, the wakeup frame may have frame(s) preceding it in the FIFO. A

pathological worst case can exist in which the RX FIFO is completely filled with data frames

and drops the wakeup frame due to FIFO overflow error.

6.1.3 FLUSHING THE RX FIFO

The device allows for the Host to the flush the entire contents of the FCT RX FIFO. When a flush is activated, the read

and write pointers of the RX FIFO are returned to their reset state.

Before flushing the RX FIFO, the device’s receiver must be stopped, as specified in Section 6.1.3.1. Once the receiver

stop completion is confirmed, the FCT RX Enable is cleared in the FIFO Controller RX FIFO Control Register (FCT_RX-

_CTL) to stop RX FIFO operation. The FCT RX Disabled bit and the RX Disabled Interrupt (RX_DIS_INT) (if enabled)

TABLE 6-2: RX COMMAND B

BITS SYMBOL DESCRIPTION

31:16 CSUM Raw L3 Checksum

This field contains the checksum computed for the frame over the L3 packet.

15:0 VTAG VLAN Tag

When the Frame is VLAN tagged bit is set, this field contains the frame’s VLAN tag.

Otherwise the contents of this field are undefined.

[15:13] - PRI

[12] - CFI

[11:0] - VID

TABLE 6-3: RX COMMAND C

BITS SYMBOL DESCRIPTION

15 WAKE Wakeup Frame Received

When set, this field indicates that the corresponding frame is identified as the wakeup

frame which cause remote wakeup over USB. This bit only has meaning when

SUSPEND3 is used and Store Wakeup Frame (STORE_WAKE) is set.

14 RFE_FAIL RFE Filter Fail

When set, this field indicates that the received wakeup frame did not pass RFE filter

rules.

This bit only has meaning when both Always Pass Wakeup Frame (PASS_WKP) and

Store Wakeup Frame (STORE_WAKE) are set and the device is in SUSPEND3.

Note: This bit should never be set when Wakeup Frame Received is not set. It is

not possible for a non-wake up frame to fail RFE filtering and still be

transmitted to the host as they would have been discarded by the FCT RX

FIFO.

13:0 - Reserved

LAN7850

DS00001993D-page 48  2015 - 2017 Microchip Technology Inc.

assert when the RX FIFO hardware has completed the disabling process. The FCT RX RESET bit can then be set in

the FIFO Controller RX FIFO Control Register (FCT_RX_CTL) to initiate the flush operation. This bit is cleared by the

hardware when the flush operation has completed.

After the RX FIFO has been flushed, the receiver may be restarted, as specified in Section 6.1.3.1. RX FIFO operation

may then be restarted by asserting the FCT RX Enable bit.

6.1.3.1 Stopping and Starting the Receiver

To stop the receiver, the Host must clear the Receiver Enable (RXEN) bit in the MAC Receive Register (MAC_RX).

When the receiver is halted, the Receiver Disabled (RXD) bit and the RX Disabled Interrupt (RX_DIS_INT) (if enabled)

will assert. Once stopped, the host software shall flush the RX FIFO. The Host must re-enable the receiver by setting

the Receiver Enable (RXEN) bit.

6.1.3.2 Flow Control

The FCT supports 802.3 flow control. The FCT can trigger the MAC to transmit a pause frame based upon programma-

ble FIFO thresholds.

The FCT provides flow control on and flow control off signals to the MAC. These signals are asserted based upon the

amount of data stored in the RX FIFO and the contents of the FCT Flow Control Threshold Register (FCT_FLOW).

When the amount of FIFO data exceeds the value specified by Flow Control On Threshold field of the FCT Flow Control

Threshold Register (FCT_FLOW), the internal flow control on signal is asserted. The MAC may then (depending on the

setting of the TX Flow Control Enable (TX_FCEN) of the Flow Control Register (FLOW)) transmit a Pause frame to

instruct its link partner to halt transmission.

At some point in the future, the amount of FIFO data will fall below the value specified by Flow Control Off Threshold

field of the FCT Flow Control Threshold Register (FCT_FLOW). This, in turn, causes the internal flow control off signal

to the MAC to assert. The MAC may then (depending on the setting of TX_FCEN) transmit a Pause frame with a value

of zero. Upon reception of the pause frame, the link partner resumes transmission.

APPLICATION NOTE: In order to avoid frame drops in the RX FIFO when using jumbo frames with flow control the

maximum frame size should be restricted to 4 KB or less. Consider the scenario where the

flow control threshold is set to 4 KB. The reception of the first 4 KB frame triggers the

transmission of a Pause frame. However, the Pause frame may be blocked if the TX path is

at that moment in the process of transmitting a 4 KB packet. While the transmitter is sending

its jumbo a frame a second jumbo frame may be received followed by a third frame before

the partner has processed the Pause frame. A larger jumbo frame can result in frame drops

which would require retransmissions by a higher layer protocol in such a corner case.

6.2 TX Path (USB to Ethernet)

The 12 KB TX FIFO buffers USB Bulk Out packets received by the URX. The FCT is responsible for extracting the Ether-

net frames embedded in the USB Bulk Out Packets and passing them to the MAC. The Ethernet frames are segmented

across the USB packets by the host software.

The FCT receives valid USB bulk out packets from the URX and writes them into the TX FIFO. The write side of the

FCT does not perform any processing on the USB packet data. No provisions for rewind of these packets on the write

side is required, as the URX manages its own buffer RAM, URX FIFO, and performs rewinds in the event that the Bulk

Note: RX Disabled Interrupt (RX_DIS_INT) will persist until the FCT RX Disabled status bit is cleared. The

Receiver Disabled (RXD) status bit in the MAC Receive Register (MAC_RX) must also be cleared in order

for RX_DIS_INT to de-assert. The RX Disabled Interrupt (RX_DIS_INT) is set in the Interrupt Status Reg-

ister (INT_STS) and is also visible to the Host via the Interrupt Endpoint.

Note: RX Disabled Interrupt (RX_DIS_INT) will persist until the Receiver Disabled (RXD) status bit is cleared.

The FCT RX Disabled status bit in the FIFO Controller RX FIFO Control Register (FCT_RX_CTL) must

also be cleared in order for RX_DIS_INT to de-assert. The RX Disabled Interrupt (RX_DIS_INT) is set in

the Interrupt Status Register (INT_STS) and is also visible via the Interrupt Endpoint.

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 49

LAN7850

Out Packet is errored and needs to be retransmitted by the Host. When the FCT writes the Ethernet frame into the FCT

TX FIFO RAM, it prepends a DWORD in front of the TX Command Words, used for internal processing, that contains

the length of the Ethernet frame.

The read side of the FCT TX FIFO is responsible for extracting the Ethernet frames.

The Ethernet frames may have been split across multiple USB buffers, as shown in Figure 6-2 which illustrates how

frames are stored in the URX FIFO. Figure 6-3 illustrates how Ethernet frames are stored in the FCT TX FIFO after being

read and assembled from the URX FIFO.

APPLICATION NOTE: Software shall not attempt to flush the FCT TX FIFO if there are pending IN transactions.

FIGURE 6-2: URX FIFO RAM

LAN7850

DS00001993D-page 50  2015 - 2017 Microchip Technology Inc.

FIGURE 6-3: FCT TX FIFO RAM

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 51

LAN7850

6.2.1 TX COMMAND FORMAT

Each buffer starts with two TX Command DWORDs, TX Command A and TX Command B, which precede the data to

be transmitted. The TX Commands instructs the FCT on the handling of the associated buffer.

The formats of TX Command A and TX Command B are shown in Table 6-4 and Table 6-5, respectively.

TX Command A contains the frame length and information to instruct how the frame must be processed. TX Command

B provides the VLAN Tag and Maximum Segment Size. The former is needed when it is desired to have a VLAN ID

inserted into the frame. The latter is used when Large Send Offload is specified. Please refer to Section 6.2.5, "VLAN

Support," on page 53 and Section 6.2.8, "Large Send Offload (LSO)," on page 55 for further details on these features.

TABLE 6-4: TX COMMAND A

BITS SYMBOL DESCRIPTION

31:30 RESERVED RESERVED

29 IGE IGMP Checksum Offload Enable

When set, the IGMP checksum will be calculated.

Note: This bit has no meaning if LSO is enabled.

28 ICE ICMP/ICMPV6 Checksum Offload Enable

When set, the ICMP (IPV4)/ICMPV6(IPV6) checksum will be calculated.

Note: This bit has no meaning if LSO is enabled.

27 LSO Large Send Offload Enable

When set, this bit enables TCP large send offload. The TCP packet will be

segmented into blocks no larger than the amount specified by Maximum Segment

Size.

26 IPE IP Checksum Offload Enable

When set, the IP checksum will be calculated.

Note: This bit has no meaning if LSO is enabled.

25 TPE TCP/UDP Checksum Offload Enable

When set, the TCP/UDP will be calculated.

Note: This bit has no meaning if LSO is enabled.

24 IVTG Insert VLAN Tag

When set, this bit instructs the FCT to insert a VLAN tag into the frame.

23 RVTG Replace VLAN Tag

This bit only applies if the TX frame has a pre-existing VLAN tag and the IVTG bit is

set.

When set, this bit causes the VLAN that exists in the frame to be overwritten by VLAN

Tag . Otherwise, a second tag shall be inserted between the source address and the

pre-existing tag.

22 FCS Insert FCS and Pad

When set, an FCS is generated and inserted for the frame.The MAC will insert

padding if the frame is less than 64 bytes.

If this bit is not set, then the MAC will never insert any padding and will assume the

frame has an FCS.

Note: It is not valid to enable checksum offloads or VLAN insertion when this bit

is cleared. Doing so shall result in the frame being erroneous and at a

minimum having an incorrect FCS.

Note: Zero-es are always used for padding.

21:20 RESERVED RESERVED

LAN7850

DS00001993D-page 52  2015 - 2017 Microchip Technology Inc.

6.2.2 TX DATA FORMAT

The TX data section begins immediately after TX Command B. TX data is contiguous until the end of the buffer. The

buffer may end on a byte boundary. Unused bytes at the end of the packet will not be sent to the MAC for transmission.

6.2.3 FCT ACTIONS ON TX FIFO READ

The FCT performs basic sanity checks on the correctness of the buffer configuration, as described in Section 6.2.4, "TX

Error Detection," on page 53. Errors in this regard indicate the TX path is out of sync, which is catastrophic and requires

a reinitialization of the TX path. A TX error can only be caused by a host software error.

The FCT performs the following steps when extracting an Ethernet frame from the TX FIFO:

• Strip out Frame Length DWORD

• Strip out TX Command A

• Strip out TX Command B

• Based upon the buffer size field of TX Command A, the FCT can numerically determine any unused bytes in the

last word of the buffer. When transferring these respective DWORDs to the MAC, the FCT adjusts the byte

enables accordingly.

• Configuration information required by the MAC from TX Command A is sent to it by the FCT through sideband

channels.

Unlike the write side, the read side of the TX FIFO supports rewinds. The rewind_fr and release_fr signals from the MAC

instruct the FCT on what actions to take on the TX FIFO buffer. The rewind_fr signal is asserted by the MAC when the

frame must be re-transmitted due to a collision. When this signal is asserted, the FCT adjusts its internal read pointer

to the start of the buffer to facilitate retransmission of the frame to the MAC. The release_fr signal is asserted by the

MAC when the frame has been successfully transmitted or the maximum number of collisions has occurred. On asser-

tion of release_fr, the FCT will purge the buffer from the TX FIFO through adjustment of its internal pointers.

19:0 LEN Frame Length [19:0]

This field indicates the size of the frame to be transmitted.

Note: If Insert FCS and Pad is not set in this Command Word, then minimum

transmit frame length must be at least 32 bytes. Values less than 32 bytes

specified in this field when Insert FCS and Pad is clear may yield untoward

operation and unexpected results.

Note: During LSO operation this field defines the LSO packet size.

TABLE 6-5: TX COMMAND B

BITS SYMBOL DESCRIPTION

31:30 RESERVED RESERVED

29:16 MSS Maximum Segment Size

When LSO is enabled, this 14-bit field specifies the maximum size of the TCP

segments that are extracted from the TX IP packet.

Note: The maximum jumbo frame size is 9 KB.

Note: The minimum permissible value for this field is 8 bytes.

15:0 VTAG VLAN Tag

When the IVTG bit is set, a VLAN Tag will be inserted into the frame as defined by

this field.

[15:13] - PRI

[12] - CFI

[11:0] - VID

TABLE 6-4: TX COMMAND A (CONTINUED)

BITS SYMBOL DESCRIPTION

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 53

LAN7850

Errors are reported via the Transmitter Error (TXE) flag, which is visible to the Host via the Interrupt Endpoint and is also

set in the Interrupt Status Register (INT_STS).

6.2.4 TX ERROR DETECTION

The following error conditions indicate that the TX path is out of sync and result in the Transmitter Error (TXE) flag being

asserted:

•MSS is less than 8 and LSO is asserted or MSS is not 0 and LSO is not asserted

•LSO is asserted and detected template header size is more than 256 bytes

•TX Command A[19:16] is not 0 and LSO is not asserted

•TX Command A[15:0] is more than 2FF7h and LSO is not asserted (since extra 2 command words will be written

to the TX FIFO as well)

•TX Command A Frame Length [19:0] field less than 32 bytes and Insert FCS and Pad is not asserted

•TX Command A[23] (Replace VLAN Tag (RVTG)) = 1 and TX Command A[24] (Insert VLAN Tag (IVTG)) = 0

•TX Command A[31:30] is not 0 (reserved bits)

•TX Command A[21:20] is not 0 (reserved bits)

•TX Command B[31:30] is not 0 (reserved bits)

6.2.5 VLAN SUPPORT

The FCT supports insertion and manipulation of VLAN tags in transmitted frames. The FCT will insert a VLAN tag when

the Insert VLAN Tag bit is set in TX Command A. In this case, the FCT will insert the tag specified by the VLAN Tag field

in TX Command B. The type field used is the default VLAN type or 8100h. An additional VLAN type can be specified by

the VLAN Type Register (VLAN_TYPE).

The FCT can also be instructed to replace a frame’s VLAN tag. This occurs when the Replace VLAN Tag bit is set in TX

Command A. In this case, the FCT will replace the existing tag with the one specified by the VLAN Tag field.

If the frame is already tagged, the FCT will insert a second VLAN tag if the Insert VLAN Tag is set and Replace VLAN

Tag is clear. The new tag will be inserted between the source address and the original VLAN tag.

6.2.6 FCS GENERATION

The TX FCT shall generate an FCS for all transmitted frames when Insert FCS and Pad bit is set in TX Command A.

Note: The FCT can be configured to stall the Bulk Out pipe when a Transmit Error is detected. This is accom-

plished via the Stall Bulk-Out Pipe Disable (SBP) bit of the Hardware Configuration Register (HW_CFG).

Note: A TX Error is a catastrophic condition that can only be caused by a host software error. The device should

be reset in order to recover from it.

Note: The Replace VLAN Tag bit has no meaning if the frame does not have a preexisting VLAN tag.

Note: The VLAN insertion and replacement occurs as a frame is read out of the FIFO.

LAN7850

DS00001993D-page 54  2015 - 2017 Microchip Technology Inc.

6.2.7 TRANSMIT CHECKSUM OFFLOAD

The FCT is capable of offloading the generation of IP, ICMP/ICMPV6, IGMP, TCP, and UDP checksums for transmitted

frames. The offload is enabled via the IP Checksum Offload Enable and TCP/UDP Checksum Offload Enable bits of TX

Command A. Table 6-6 summarizes the transmit checksum offload capabilities.

Note 6-1 Fragmentation is not supported. Hop-by-Hop, Destination, and Routing options are supported.

Please refer to Section 7.2, "Checksum Offload," on page 67 for a discussion of the implementation of the checksum

offload. Section 7.2 specifically addresses the receive checksum offload case. The pseudo header formats and scope

of the checksum, however, are the same for both receive and transmit offload operations.

6.2.7.1 Configuration

In order to utilize the checksum offload, the host software performs the following steps:

1. Host software receives an IP packet from the application. The software must determine if a TCP or UDP packet

is encapsulated.

2. The driver must indicate the checksum calculation to be offloaded by setting the proper bits in TX Command A.

For IP checksum offload, the IP Checksum Offload Enable bit is set. For TCP or UDP checksum offload, the TCP/

UDP Checksum Offload Enable bit is set. To enable ICMP and IGMP checksums the ICMP/ICMPV6 Checksum

Offload Enable and IGMP Checksum Offload Enable bits are set respectively.

TABLE 6-6: CHECKSUM OFFLOAD CAPABILITY SUMMARY

PACKET TYPE

CHECKSUM

CAPABLE

TCP/UDP

CHECKSUM

CAPABLE

ICMP

CHECKSUM

CAPABLE

IGMP

CHECKSUM

CAPABLE

Type II Ethernet Yes Yes Yes Yes

SNAP Header Yes Yes Yes Yes

Single VLAN Tag Yes Yes Yes Yes

Stacked VLAN Tags Yes Yes Yes Yes

IPv4 Yes Yes Yes Yes

IPv6 No Yes Yes No

IP Fragment Yes No No No

IP Options Yes Yes Yes Yes

TCP or UDP Options Yes Yes N/A N/A

L4 protocol is not

TCP or UDP

Yes No N/A N/A

IPv6 with IP options

next headers

Note 6-1

No Yes Yes No

IPv6 tunneled over

IPv4

Yes (IPv4) Yes Yes No

IPv4 tunneled over

IPv4

No No No No

Note: IPv6 does not have a header checksum.

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 55

LAN7850

6.2.8 LARGE SEND OFFLOAD (LSO)

Large send offload (LSO), also known as TCP Segmentation, allows the TX FCT to segment a large TCP packet into

multiple Ethernet frames. This feature relieves a significant burden on Host CPU resources.

The assertion of the Large Send Offload Enable bit in TX Command A enables this feature in the FCT. The size of the

final Ethernet frames are determined by the Maximum Segment Size field in TX Command B, and the size of the encap-

sulating headers. Figure 6-4 illustrates a high level view of the TCP segmentation process.

The TX FCT performs the following operations:

• Breaks the large TCP packet into segments

• Creates the Ethernet Header

• Creates the IP Header

• Creates the TCP Header

• Calculates the IP checksum (IPv4 only)

• Calculates the TCP checksum

FIGURE 6-4: TCP SEGMENTATION

LAN7850

DS00001993D-page 56  2015 - 2017 Microchip Technology Inc.

The TCP payload stored in URX buffer RAM is preceded by template headers. They are composed of Ethernet, IP, and

TCP headers. The template header may not exceed 256 bytes. The FCT copies the template headers and stores them

in the LSO Template Header RAM. They are used as the basis for the headers of all future segments.

The following formats are supported for LSO.

• Ethernet 802.3

• IEEE 802.1q VLAN

• Ethernet Type II

• SNAP Header

• IPv4

• IPv6

• IP Options

• TCP Options

• IPv6 with next header options

Hop-by-Hop supported

Destination supported

Routing supported

Fragmentation not supported

6.2.8.1 Configuration

In order to prepare the FCT for LSO, the following steps must be taken by the Host software.

1. The protocol stack receives a block of data from the application into its own local buffer. Sufficient space is

reserved in the local buffer for the construction of the TX Command Words and template headers prior to the

TCP payload.

2. Template headers are constructed and inserted in front of the TCP payload in the local buffer. Software must

ensure the following requirements are met in the template headers:

- The IPv4 MF bit is not set.

- The IPv4 Fragment Offset field is zero.

- The IPv4, or IPv6, packet length is set to zero.

- The IPv4 Identification field is set appropriately.

- The TCP Sequence Number field is set to identify the first byte of the TCP payload.

- The TCP FIN bit is set as appropriate for the last packet of the segment.

- The TCP PSH bit is set as appropriate for the last packet of the segment.

- The TCP flags URG, RST, and SYN are not set. The urgent pointer is set to zero.

3. Software must then configure the TX Command Words as follows to enable Large Send Offload:

- The Large Send Offload Enable bit is set in TX Command A.

- The Maximum Segment Size field is set in TX Command A. The MSS indicates the size of the packet data

that is being encapsulated. This value does not include the Ethernet header, IP header, or TCP header.

- If VLAN operation is supported, then the Insert VLAN Tag bit, Replace VLAN Tag bit, and the VLAN Tag

field must be set appropriately in TX Command B.

4. Software transmits the contents of its local buffer to the device via the USB interface. Subsequent data may be

transmitted via the USB interface, depending on the size of the local buffer and the total size of the data to be

transmitted from the application.

Note: LSO is not supported for UDP packets.

Note: IP tunneling is not supported for LSO.

Note: Steps 1. and 2., with the exception of reservation of space for the TX Command Words, may be accom-

plished by the Host operating system.

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 57

LAN7850

6.2.8.2 Processing

The FCT recognizes that it has received a frame for LSO by the assertion of the Large Send Offload Enable bit in TX

Command A when it reads the command word out of URX Buffer RAM. The FCT copies and stores the template header.

For subsequent segments, headers based upon the template header are inserted. Additionally, a frame length word is

constructed for each segment. With the exception of the last segment, the length for all segments will equal to the Max-

imum Segment Size.

Figure 6-5 illustrates how frame data is stored in the TX FIFO when LSO is enabled. The total size of the packet requires

four segments to be created. The last segment having a size less than the Maximum Segment Size.

FIGURE 6-5: LSO TX FIFO FRAME STORAGE

LAN7850

DS00001993D-page 58  2015 - 2017 Microchip Technology Inc.

The FCT is responsible for performing the following functions for the LSO:

1. Compute the IP checksum (IPv4)

2. Compute the IP pseudo-header

3. Compute the TCP checksum

4. Compute the IP packet length

5. Compute the IP Identification field (IPv4 only)

6. Compute the TCP Sequence Number field

7. If there are any IP options, the FCT copies them unmodified into each packet. Likewise, any TCP options are

also copied unmodified into each TCP packet.

8. Set the TCP FIN and PSH bits accordingly

9. VLAN tag processing

10. Request the MAC to generate an FCS for each frame by setting the Insert FCS and Pad in the TX Command A

it constructs for the frame.

If there is a SNAP header, the FCT must update the length field as required for an 802.3 frame.

The following sections break down the duties of the FCT on per segment basis for creating the frame’s headers.

6.2.8.2.1 Initial Packet Generation

For the first packet of a segment, the FCT performs the following header calculations:

• IP Length = Maximum Segment Size + IP Header Size + TCP Header Size

• Total Frame Length = IP Length + L2 Header + VLAN

• Ethernet Length = IP Length

• Compute IP Checksum (IPv4)

• IP Identification = Value programmed in template IP header

• Compute TCP Checksum

• TCP Sequence Number = Value programmed in template TCP header

• TCP FIN flag = 0

• TCP PSH flag = 0

6.2.8.2.2 Intermediate Packet Generation

For the intermediary packets of a segment, the FCT performs the following header calculations:

• IP Length = Maximum Segment Size + IP Header Size + TCP Header Size

• Total Frame Length = IP Length + L2 Header + VLAN

• Ethernet Length = IP Length

• Compute IP Checksum (IPv4)

• IP Identification = Increment from value in previous IP packet

• Compute TCP Checksum

• TCP Sequence Number = Value of previous TCP header + Maximum Segment Size

• TCP FIN flag = 0

• TCP PSH flag = 0

6.2.8.2.3 Final Packet Generation

For the last packet of a segment, the FCT performs the following header calculations:

• Last frame TCP payload length = TCP payload length - N* Maximum Segment Size. (N is the number of previ-

ously transmitted segments.)

• IP Length = Last Frame TCP Payload Length + IP Header Size + TCP Header Size

• Total Frame Length = IP Length + L2 Header + VLAN

• Ethernet Length = IP Length

Note: The FCT ignores the IP MF flag, NF flag, and fragment offset field. The FCT ignores the TCP URG, RST,

and SYN flags. The TCP urgent pointer is also ignored.

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 59

LAN7850

• Compute IP Checksum (IPv4)

• IP Identification = Increment from value in previous IP packet

• Compute TCP Checksum

• TCP Sequence Number = Value of previous TCP header + Maximum Segment Size

• TCP FIN flag is set to the value specified in the TCP template header

• TCP PSH flag is set to the value specified in the TCP template header

6.2.9 FLUSHING THE TX FIFO

The device allows for the Host to the flush the entire contents of the FCT TX FIFO. When a flush is activated, the internal

read and write pointers for the TX FIFO are returned to their reset state.

Before flushing the TX FIFO, the device’s transmitter must be stopped, as specified in Section 6.2.10. Once the trans-

mitter stop completion is confirmed, the FCT TX Enable bit is cleared in the FIFO Controller RX FIFO Control Register

(FCT_RX_CTL) to stop TX FIFO operation. The FCT TX Disabled bit and the TX Disabled Interrupt (TX_DIS_INT) (if

enabled) assert when the TX FIFO hardware has completed the disabling process. The FCT TX Reset bit shall then be

set in the FIFO Controller RX FIFO Control Register (FCT_RX_CTL) to initiate the flush operation. This bit is cleared by

the hardware when the flush operation has completed.

After the TX FIFO has been flushed, the transmitter may be restarted as specified in Section 6.2.10. TX FIFO operation

may then be restarted by asserting the FCT TX Enable bit.

APPLICATION NOTE: Software shall not attempt to flush the TX FIFO if there are pending URBs on the Bulk Out

EP.

6.2.10 STOPPING AND STARTING THE TRANSMITTER

To stop the transmitter, the Host must perform the following steps:

1. Software clears the FCT TX Enable bit in the FIFO Controller TX FIFO Control Register (FCT_TX_CTL).

2. Software polls the FCT TX Disabled bit in the FIFO Controller TX FIFO Control Register (FCT_TX_CTL) to con-

firm the FCT TX is disabled.

3. The FCT TX Disabled bit is set in the FIFO Controller TX FIFO Control Register (FCT_TX_CTL).

4. Software halts the MAC transmitter by clearing the Transmitter Enable (TXEN) bit in the MAC Transmit Register

(MAC_TX).

5. Software polls the Transmitter Disabled (TXD) bit in the MAC Transmit Register (MAC_TX) to confirm the MAC

transmitter is disabled.

6. The Transmitter Disabled (TXD) status bit is set to indicate that the MAC TX has halted.

APPLICATION NOTE: As an alternative to polling FCT TX Disabled and/or Transmitter Disabled (TXD), the TX

Disabled Interrupt (TX_DIS_INT) bit in the Interrupt Status Register (INT_STS) may be used.

APPLICATION NOTE: When the device is configured for half-duplex operation, it is possible for a collision to

happen after FCT TX Enable is cleared but before the frame has completed transmitted. In

this case the MAC will assert abort signaling to the FCT and the frame shall be dropped by

the FCT.

Once the TX path is stopped, the Host can optionally flush the TX FIFO as discussed in Section 6.2.9. The Host may

re-enable the transmitter by setting the Transmitter Enable (TXEN) bit in the MAC Transmit Register (MAC_TX) followed

by setting the FCT TX Enable bit in the FIFO Controller TX FIFO Control Register (FCT_TX_CTL).

If there are frames pending in the TX FIFO (i.e., the TX FIFO was not purged), the transmission will resume with this

data.

Note: TX Disabled Interrupt (TX_DIS_INT) will persist until both the FCT TX Disabled status bit and the Trans-

mitter Disabled (TXD) status bit in the MAC Transmit Register (MAC_TX) are cleared.

Note: The MAC continues to read the frame currently being transmitted from the FCT until the frame is transmit-

ted. After the frame is transmitted, the FCT TX Disabled bit will assert.

LAN7850

DS00001993D-page 60  2015 - 2017 Microchip Technology Inc.

7.0 RECEIVE FILTERING ENGINE (RFE)

The RFE receives Ethernet frames from the Ethernet MAC, processes them, and passes them to the RX FCT. The RFE

is responsible for filtering the received Ethernet frames, verifying the TCP/UDP/ICMP/IGMP and IP checksum, and

removing the VLAN tag.

When receiving a frame from the MAC, the RFE will obtain the frame data and status information. Upon completion of

frame processing, the RFE encapsulates its status with the status information obtained from the MAC, and passes this

information (along with the frame data) on to the FCT in the form of RX Command A, RX Command B and RX Command

The RFE, if enabled, can remove a VLAN tag from the frame. VLAN tag stripping is controlled by the Enable VLAN Tag

Stripping bit of the Receive Filtering Engine Control Register (RFE_CTL). If this bit is set, the tag will be stripped. If clear,

the RFE will not modify the frame in any way.

The RFE provides the Layer 3 Checksum (if enabled) and VLAN ID via RX Command B, while RX Command A and RX

Command C contain the frame’s status.

When the RFE determines a frame has a checksum error, it sets the appropriate error bits in RX Command A to identify

the error condition.

7.1 Frame Filtering

The RFE filters Ethernet frames by processing the Ethernet source address, Ethernet destination address, and VLAN

ID.

The following frame filtering options are supported:

• Global Unicast (Receive all unicast frames)

• Global Multicast (Receive all multicast frames)

• Broadcast Filter (Discard all broadcast frames)

• Perfect Address Filtering

• Hash Address Filtering

• VLAN Filtering (Untagged/VID)

7.1.1 PERFECT ADDRESS FILTERING

The RFE provides for perfect address filtering. This represents the first level of frame filtering. There are 33 addresses

available for this purpose, which are stored in the MAC Address Perfect Filter Registers (ADDR_FILTx). Each entry may

be configured as either a destination or a source address. Table 7-1 illustrates an entry.

Note: If multiple VLAN tags are present in a frame, the RFE only removes the first tag (adjacent to the MAC

source address).

Note: The FCT does not rewind frames that failed checksum validation from the FCT RX FIFO.

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 61

LAN7850

Destination address filtering is enabled via the Enable Destination Address Perfect Filtering (DPF) bit of the Receive

Filtering Engine Control Register (RFE_CTL). Source address filtering is enabled by the Enable Source Address Perfect

Filtering (SPF) bit. If both source and destination address filtering are enabled, then a frame will be discarded if a match

is not present for both fields. In this case, the destination address match may also occur via the hash filter.

After receiving a frame, the RFE will compare all 33 entries in the table, after parsing out the destination and source

address. Filters are added and changed via the MAC Address Perfect Filter Registers (ADDR_FILTx). The entries may

be changed during run time.

7.1.2 HASH ADDRESS FILTERING

The RFE supports imperfect filtering of the MAC destination address. This allows the number of address filters to exceed

the number provided by the perfect filters.

By default, the hash filtering is enabled for both multicast and unicast destination addresses. Hash filtering never applies

to broadcast addresses. The Enable Multicast Address Hash Filtering (MHF) and Enable Destination Address Hash Fil-

tering (DHF) bits in the Receive Filtering Engine Control Register (RFE_CTL) enables the address hash filter for the

respective frame type.

The RFE computes the hash on the destination address via a CRC-32 calculation. The hash result is used to index the

Hash Address Filter table that is stored in the VHF. Figure 7-3 illustrates the layout of the VHF and the position of the

Hash Address Filter table within it. The filter table is 16 DWORDS in length and holds up to 512 entries. Each entry is

a single bit within the 16 DWORD array.

At the start of a new frame, the CRC-32 is initialized with the value FFFFFFFFh. The CRC-32 is then updated with each

byte of the destination address.

The following algorithm is used to update the CRC-32 at that time:

Let:

^ denote the exclusive or operator.

Data [7:0] be the received data byte to be included in the checksum.

CRC[31:0] contain the calculated CRC-32 checksum.

F0 … F7 be intermediate results, calculated when a data byte is determined to be part of the CRC-32.

Calculate:

F0 = CRC[31] ^ Data[0]

F1 = CRC[30] ^ Data[1]

F2 = CRC[29] ^ Data[2]

F3 = CRC[28] ^ Data[3]

TABLE 7-1: PERFECT ADDRESS ENTRY FORMAT

BIT DESCRIPTION

49 Address Valid

When set, this bit indicates that the entry has valid data and is used in the perfect filtering.

48 Address Type

When set, this bit indicates the MAC Address represents the MAC source address. Otherwise this

entry applies to the MAC destination address.

47:0 MAC Address

This field holds the 48-bit MAC address that will be matched by the RFE.

The MAC address storage scheme matches that for the RXADDRH and RXADDRL registers, see

Table 15-4, "RX_ADDRL, RX_ADDRH Byte Ordering".

Note: The hash filter can result in false positives. Therefore, the Host must validate the destination address.

LAN7850

DS00001993D-page 62  2015 - 2017 Microchip Technology Inc.

F4 = CRC[27] ^ Data[4]

F5 = CRC[26] ^ Data[5]

F6 = CRC[25] ^ F0 ^ Data[6]

F7 = CRC[24] ^ F1 ^ Data[7]

The CRC-32 is updated as follows:

CRC[31] = CRC[23] ^ F2

CRC[30] = CRC[22] ^ F0 ^ F3

CRC[29] = CRC[21] ^ F0 ^ F1 ^ F4

CRC[28] = CRC[20] ^ F1 ^ F2 ^ F5

CRC[27] = CRC[19] ^ F2 ^ F3 ^ F6

CRC[26] = CRC[18] ^ F3 ^ F4 ^ F7

CRC[25] = CRC[17] ^ F4 ^ F5

CRC[24] = CRC[16] ^ F5 ^ F6

CRC[23] = CRC[15] ^ F0 ^ F6 ^ F7

CRC[22] = CRC[14] ^ F1 ^ F7

CRC[21] = CRC[13] ^ F2

CRC[20] = CRC[12] ^ F3

CRC[19] = CRC[11] ^ F0 ^ F4

CRC[18] = CRC[10] ^ F0 ^ F1 ^ F5

CRC[17] = CRC[9] ^ F0 ^ F1 ^ F2 ^ F6

CRC[16] = CRC[8] ^ F1 ^ F2 ^ F3 ^ F7

CRC[15] = CRC[7] ^ F0 ^ F2 ^ F3 ^ F4

CRC[14] = CRC[6] ^ F0 ^ F1 ^ F3 ^ F4 ^ F5

CRC[13] = CRC[5] ^ F1 ^ F2 ^ F4 ^ F5 ^ F6

CRC[12] = CRC[4] ^ F0 ^ F2 ^ F3 ^ F5 ^ F6 ^ F7

CRC[11] = CRC[3] ^ F0 ^ F1 ^ F3 ^ F4 ^ F6 ^ F7

CRC[10] = CRC[2] ^ F1 ^ F2 ^ F4 ^ F5 ^ F7

CRC[9] = CRC[1] ^ F0 ^ F2 ^ F3 ^ F5 ^ F6

CRC[8] = CRC[0] ^ F0 ^ F1 ^ F3 ^ F4 ^ F6 ^ F7

CRC[7] = F0 ^ F1 ^ F2 ^ F4 ^ F5 ^ F7

CRC[6] = F1 ^ F2 ^ F3 ^ F5 ^ F6

CRC[5] = F2 ^ F3 ^ F4 ^ F6 ^ F7

CRC[4] = F3 ^ F4 ^ F5 ^ F7

CRC[3] = F4 ^ F5 ^ F6

CRC[2] = F5 ^ F6 ^ F7

CRC[1] = F6 ^ F7

CRC[0] = F7

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 63

LAN7850

The upper 9-bits, [31:23] of the resultant CRC-32 is extracted by the RFE. This value provides the bit location in the filter

table to be examined. If the respective bit is asserted, then the frame passes the hash filter. Bits 31:28 reference the

DWORD within the table that is to be used, while bits 27:23 index the bit entry. Figure 7-1 illustrates this decoding.

FIGURE 7-1: HASH FILTER DECODING

LAN7850

DS00001993D-page 64  2015 - 2017 Microchip Technology Inc.

7.1.3 VLAN FILTERING

The RFE provides the ability to filter on the VLAN tag. A VLAN tag is present when the type field matches the value

indicated by the VLAN Type Register (VLAN_TYPE) or 8100h.

When multiple VLAN tags are present, the RFE only considers the first tag. This is defined as the tag immediately adja-

cent to the source address.

The RFE may be configured to discard frames or pass frames that do not have a VLAN tag. This is controlled by the

Untagged Frame Filtering (UF) bit of the Receive Filtering Engine Control Register (RFE_CTL).

When the RFE encounters a tagged frame, the VLAN tag is stripped. The VLAN ID is placed into the VLAN Tag field of

RX Command B and the Frame is VLAN tagged bit of RX Command A is set.

The 12-bit VID is extracted from the VLAN tag and used for VLAN filtering if the Enable VLAN Filtering (VF) bit of the

Receive Filtering Engine Control Register (RFE_CTL) is set. The VID maps to a bit in the VLAN ID Filter Table contained

in the VMF. Figure 7-2 illustrates the mapping. If the corresponding bit is set, then the frame passes the VLAN filtering.

If filtering is enabled, and the VID is not present in the VLAN ID Filter Table (mapped bit is clear), then the frame is

dropped.

FIGURE 7-2: VLAN ID FILTER DECODING

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 65

LAN7850

7.1.4 VHF ORGANIZATION

The VHF RAM contains the tables necessary to perform VLAN filtering and hash based destination address filtering.

Figure 7-2 shows the locations of the VLAN filter table and the Hash filter table. The table’s contents are addressed on

a DWORD boundary.

VHF entries are added and changed via the data port registers. The Data Port Select Register (DP_SEL) is used to

specify the VHF RAM. The VHF entries may be changed during run time.

After a reset event, the RFE will automatically initialize the contents of the VHF to 0h. While the initialization is in prog-

ress, data port accesses to this RAM will be wait stated.

FIGURE 7-3: VHF RAM LAYOUT

LAN7850

DS00001993D-page 66  2015 - 2017 Microchip Technology Inc.

7.1.5 DETAILED FILTERING RULES

Figure 7-4 illustrates the exact filtering process performed by the RFE.

FIGURE 7-4: DETAILED FILTERING RULES

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 67

LAN7850

7.2 Checksum Offload

The RFE supports the offloading of the IP checksum, TCP/UDP checksum, and a L3 checksum. Both IPv4 and IPv6

are supported. The RFE supports the following IEEE 802.3 frame types:

• Type II Ethernet frames

• Ethernet SNAP frames

802.1q VLAN tags are supported. The RFE is capable of recognizing up to two VLAN tags and excludes them from the

checksum calculations. The type used to recognize a VLAN tag is defined by the VLAN Type Register (VLAN_TYPE).

This value defaults to 8100h.

7.2.1 IP CHECKSUM

A value of 0800h in the type field indicates the frame is IPv4. A value of 86DDh in the type field indicates the frame is

IPv6.

IP checksum offload is enabled when the Enable IP Checksum Validation bit of the Receive Filtering Engine Control

is asserted and the RFE signals the FCT to abort the frame. The IP Checksum Error will also be asserted if the IP header

is less than 20 bytes in size, as indicated by the IP Header Length.

The IP checksum is the 16-bit one’s complement of the one’s complement sum of all 16-bit groups in the IP header. The

checksum is verified by calculating he 16-bit one’s complement sum across the IP header. This calculation includes the

IP checksum itself. If the final result is FFFFh, then the packet has a valid IP checksum.

7.2.2 LAYER 3 CHECKSUM

The Layer 3 checksum and TCP/UDP checksum are enabled when the Enable TCP/UDP Checksum Validation bit of

the Receive Filtering Engine Control Register (RFE_CTL) is set. The Layer 3 checksum and IGMP checksum are

enabled when the Enable IGMP Checksum Validation bit of the Receive Filtering Engine Control Register (RFE_CTL)

is set. Likewise the Layer 3 checksum and ICMP checksum are enabled when the Enable ICMP Checksum Validation

bit of the Receive Filtering Engine Control Register (RFE_CTL) is set.

The Layer 3 checksum is the 16-bit one’s complement sum of the entire layer 3 packet. The checksum is calculated 16

bits at a time. In the case of an odd sized frame, an extra byte of zero is used to pad up to 16 bits.

Consider the following packet: DA, SA, Type, B0, B1, B2 … BN, FCS

Let [A, B] = A*256 + B

If the packet has an even number of octets then:

checksum = [B1, B0] + C0 + [B3, B2] + C1 + … + [BN, BN-1] + CN-1

Where C0, C1,... CN-1 are the carry out results of the intermediate sums.

If the packet has an odd number of octets then:

checksum = [B1, B0] + C0 + [B3, B2] + C1 + … + [0, BN] + CN-1

Note: The IP header may be larger than 5 DWORDs (20 bytes) if IP options are present.

IPv6 does not have an IP checksum.

LAN7850

DS00001993D-page 68  2015 - 2017 Microchip Technology Inc.

Figure 7-5 illustrates the scope of the Layer 3 checksum over a type II Ethernet frame. The calculation starts after the

type field and does not include the FCS.

Consider the case where the frame is a 802.3 Ethernet frame with a VLAN tag. The RFE bypasses DA, SA, VLAN tag,

SNAP header, and type fields. The calculation begins at the byte immediately following the type field. The calculation

does not include the FCS.

The checksum is placed in the Raw L3 Checksum field in RX Command B. This raw checksum is useful in cases such

as when the layer 3 protocol is not IP or IP fragmented packets.

FIGURE 7-5: LAYER 3 CHECKSUM - TYPE II ETHERNET

FIGURE 7-6: LAYER 3 CHECKSUM - 802.3 FRAME

Note: If neither the Enable TCP/UDP Checksum Validation, Enable ICMP Checksum Validation nor Enable IGMP

Checksum Validation bits of the Receive Filtering Engine Control Register (RFE_CTL) are set, then the

value of the Raw L3 Checksum field is undefined.

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 69

LAN7850

7.2.3 TCP CHECKSUM

If the RFE detects a TCP header, it will attempt to verify the TCP checksum when the Enable TCP/UDP Checksum Val-

idation bit in the Receive Filtering Engine Control Register (RFE_CTL) is set. TCP is indicated when the IP Protocol is 6.

The TCP checksum covers the TCP header, TCP data, and pseudo header. The pseudo header consists of the Source

IP Address, Destination IP Address, IP Protocol Number, and the total number of bytes in the TCP header and data.

The latter field is calculated as follows:

Total Bytes in TCP Header and Data = IP Total Length - 4*(IP Header Length)

Because the checksum is done in 16-bit quantities, a pad byte of zero may need to be placed adjacent to the last data

byte. This is required in the case where the total number of bytes is odd. Figure 7-7 (IPv4) and Figure 7-8 (IPv6) illustrate

the scope of the TCP checksum.

The RFE calculates a 16-bit one’s complement sum over the TCP header, TCP data, and pseudo header. If the final

result is FFFFh, then the packet passes the TCP checksum. If the final result is not FFFFh, then the checksum fails and

the TCP/UDP/ICMP/IGMP Checksum Error bit is set.

If the IP packet is fragmented, the TCP checksum is not validated. A fragmented packet is determined by the following

conditions.

• The first fragment is indicated by the IP header’s MF flag being set and fragment offset having a value of zero.

• Subsequent fragments are determined by the IP Fragment Offset field having a value greater than zero.

Note: There is no length field in the TCP header that can be used. This must be calculated via the IP header.

Note: See RFC 1624 for further details on checksum computation.

FIGURE 7-7: TCP CHECKSUM - IPV4

LAN7850

DS00001993D-page 70  2015 - 2017 Microchip Technology Inc.

FIGURE 7-8: TCP CHECKSUM - IPV6

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 71

LAN7850

7.2.4 UDP CHECKSUM

If the RFE detects a UDP header, it will attempt to verify the UDP checksum when the Enable TCP/UDP Checksum

Validation bit in the Receive Filtering Engine Control Register (RFE_CTL) is set. UDP is indicated when the IP protocol

is 17. The UDP checksum calculation is nearly identical to the TCP checksum procedure. The scope of the UDP check-

sum is shown in Figure 7-9 (IPv4) and Figure 7-10 (IPv6).

The UDP checksum is optional for IPv4. A value of 0000h indicates that the checksum is not used. If IPv4 is used, then

the TCP/UDP/ICMP/IGMP Checksum Error status bit is not asserted after encountering this condition.

A zero UDP checksum is not valid for IPv6. When IPv6 is used, a checksum of 0000h results in the assertion of the TCP/

UDP/ICMP/IGMP Checksum Error bit.

If the IP packet is fragmented, the UDP checksum is not validated. See Section 7.2.3 for further details on how to identify

a fragmented packet.

Note: The UDP Length field in the pseudo header is equivalent to the UDP message length in the UDP header.

Therefore, unlike the TCP case, the length does not have to be calculated numerically from the IP header.

Note: Typically, when the UDP checksum generation results in 0000h, a value of FFFFh (0-) is inserted into the

UDP checksum field.

FIGURE 7-9: UDP CHECKSUM - IPV4

LAN7850

DS00001993D-page 72  2015 - 2017 Microchip Technology Inc.

FIGURE 7-10: UDP CHECKSUM - IPV6

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 73

LAN7850

7.2.5 ICMP CHECKSUM

If the RFE detects an ICMP header, it will attempt to verify the ICMP checksum when configured. ICMP is indicated

when the IP protocol is 1 for an IPv4 datagram. The ICMP checksum is the 16-bit ones complement of the one's com-

plement sum of the ICMP message starting with the ICMP Type field.

ICMPv6 is utilized with IPv6. This is indicated by a next header value of 58. In this case the checksum is the 16-bit one's

complement of the one's complement sum of the entire ICMPv6 message, starting with the ICMPv6 message type field,

and prepended with a “pseudo-header” of IPv6 header fields. The inclusion of a pseudo-header in the ICMPv6 check-

sum is a change from IPv4. See Figure 7-8 for a definition of the IPv6 pseudo-header. The Next Header value used in

the pseudo-header is 58.

ICMP checksum validation is enabled by setting the Enable ICMP Checksum Validation bit in the Receive Filtering

Engine Control Register (RFE_CTL).

If the IP packet is fragmented, the ICMP checksum is not validated. See Section 7.2.3 for further details on how to iden-

tify a fragmented packet.

7.2.6 IGMP CHECKSUM

If the RFE detects an IGMP header, it will attempt to verify the IGMP checksum when configured. IGMP is indicated

when the IP protocol is 2. The checksum is the 16-bit one's complement of the one's complement sum of the whole

IGMP message (the entire IP payload).

IGMP checksum validation is enabled by setting the Enable IGMP Checksum Validation bit in the Receive Filtering

Engine Control Register (RFE_CTL).

If the IP packet is fragmented, the IGMP checksum is not validated. See Section 7.2.3 for further details on how to iden-

tify a fragmented packet.

7.2.6.1 Checksum Summary

Table 7-2 summarizes the checksum offload ability of the RFE for various L3 and L4 configurations.

TABLE 7-2: CHECKSUM OFFLOAD CAPABILITY SUMMARY

PACKET TYPE

CHECKSUM

CAPABLE

TCP/UDP

CHECKSUM

CAPABLE

ICMP

CHECKSUM

CAPABLE

IGMP

CHECKSUM

CAPABLE RAW

CHECKSUM

Type II Ethernet Yes Yes Yes Yes Yes

SNAP Header Yes Yes Yes Yes Yes

Single VLAN

Tag

Yes Yes Yes Yes Yes

Stacked VLAN

Tags

Yes Yes Yes Yes Yes

IPv4 Yes Yes Yes Yes Yes

IPv6 No Yes Yes No Yes

IP Fragment Yes No No No Yes

IP Options Yes Yes Yes Yes Yes

TCP or UDP

Options

Yes Yes N/A N/A Yes

L4 protocol is

not TCP or UDP

Yes No N/A N/A Yes

L3 protocol is

not IP

No No No No Yes

LAN7850

DS00001993D-page 74  2015 - 2017 Microchip Technology Inc.

Note 7-1 Fragmentation is not supported. Hop-by-Hop, Destination, and Routing extension headers are

supported.

IPv6 with next

header options

Note 7-1

No Yes Yes No Yes

IPv6 tunneled

over IPv4

Yes (IPv4) Yes Yes No Yes

IPv4 tunneled

over IPv4

No No No No Yes

TABLE 7-2: CHECKSUM OFFLOAD CAPABILITY SUMMARY (CONTINUED)

PACKET TYPE

CHECKSUM

CAPABLE

TCP/UDP

CHECKSUM

CAPABLE

ICMP

CHECKSUM

CAPABLE

IGMP

CHECKSUM

CAPABLE RAW

CHECKSUM

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 75

LAN7850

8.0 10/100/1000 ETHERNET MAC

The Ethernet Media Access controller (MAC) incorporates the essential protocol requirements for operating an Ether-

net/IEEE 802.3-compliant node and provides an interface to the Ethernet PHY. The MAC can operate in full-duplex 1000

Mbps or half/full-duplex 10/100 Mbps mode.

When operating in half-duplex mode, the MAC complies fully with Section 4 of ISO/IEC 8802-3 (ANSI/IEEE standard)

and ANSI/IEEE 802.3 standards. When operating in full-duplex mode, the MAC complies with IEEE 802.3x full-duplex

operation standard.

The MAC provides programmable enhanced features designed to minimize Host supervision, bus utilization, and pre-

or post-message processing. These features include the ability to disable retries after a collision, dynamic FCS (Frame

Check Sequence) generation on a frame-by-frame basis, automatic pad field insertion and deletion to enforce minimum

frame size attributes, and automatic retransmission and detection of collision frames.

The primary attributes of the MAC Function are:

• Interfaces to Ethernet PHY

• Transmit and receive message data encapsulation

• Framing (frame boundary delimitation, frame synchronization)

• Error detection (physical medium transmission errors)

• FCS checking/stripping/generation

• Preamble stripping/generation

• Media access management

• Medium allocation (collision detection, except in full-duplex operation)

• Contention resolution (collision handling, except in full-duplex operation)

• Flow control during full-duplex mode

• Decoding of control frames (PAUSE command) and disabling the transmitter

• Generation of control frames (PAUSE command)

• Maintains minimum inter packet gap (IPG)

• Magic packet/Wake-On-LAN (WOL) detection

• Remote wakeup frame detection

• Neighbor Solicitation offload

• ARP offload

• Implements Simple Network Management Protocol (SNMP) and Remote Monitoring (RMON) management

counter sets

The transmit and receive data paths are separate within the device from the MAC to the USB interface, allowing the

highest performance, especially in full-duplex mode.

On the backend, the MAC interfaces with the PHY via internal GMII and MII ports. The GMII port is used for 1000 Mbps

operation, while the MII port is used for 10/100 Mbps operation. The device’s registers also provide a mechanism for

accessing the PHY’s registers through the internal SMI (Serial Management Interface) bus.

The FCT RX and TX FIFO, as well as the URX FIFO and UTX FIFO, allow increased packet buffer storage to the MAC.

The FIFOs are a conduit between the USB interface and the MAC through which all transmitted and received data and

various command/status information is passed. Deep FIFOs allow a high degree of latency tolerance relative to the var-

ious transport and OS software stacks, reducing and minimizing overrun conditions.

8.1 Collision Handling

When a collision is detected, the transmission of data is halted and a Jam pattern is transmitted. After a collision, the

MAC will attempt to retransmit the frame. The time the frame is retransmitted is determined by the “truncated binary

exponential back-off” algorithm. The back-off limit is selected by the Back Off Limit (BOLMT) field of the Hardware Con-

figuration Register (HW_CFG). The units of the delay is slot times, where a slot time is equivalent to a 512-bit time. The

MAC also controls the rewind_fr and release_fr signals to the FCT. The rewind_fr signal is used to support frame

retransmission after a collision occurs. After a frame has been successfully transmitted or aborted due to excessive col-

lisions or late collisions, the release_fr signal asserts to indicate the MAC is done processing the current frame and is

ready for the next frame.

LAN7850

DS00001993D-page 76  2015 - 2017 Microchip Technology Inc.

8.2 Flow Control

The device’s Ethernet MAC supports full-duplex flow control using the pause operation and control frame. Full-duplex

flow control is also supported based on manual transmission of flow control frames or via automatic transmission of flow

control frames, as determined by high and low watermark threshold levels in the RX FIFO.

8.2.1 FULL-DUPLEX FLOW CONTROL

The pause operation inhibits data transmission of data frames for a specified period of time. A Pause operation consists

of a frame containing the globally assigned multicast address (01-80-C2-00-00-01) or the programmed unicast address,

the PAUSE opcode, and a parameter indicating the quantum of slot time (512 bit times) to inhibit data transmissions.

The PAUSE parameter may range from 0 to 65,535 slot times.

The RX Flow Control Enable (RX_FCEN) bit of the Flow Control Register (FLOW) enables the receive MAC flow control

function. When this bit is set, the Ethernet MAC logic, on receiving a frame with the reserved multicast address or uni-

cast address and PAUSE opcode, inhibits data frame transmissions for the length of time indicated. If a Pause request

is received while a transmission is in progress, then the pause will take effect after the transmission is complete. Control

frames are received and processed by the MAC. The setting of the Forward Pause Frames (FPF) bit of the Flow Control

Transmit pause frames may be generated manually, or automatically, based on RX FIFO threshold levels. Setting the

Force Transmission of TX Flow Control Frame (FORCE_FC) bit of the Flow Control Register (FLOW) will initiate the

transmission of a Pause Control Frame. The Pause time is specified in the Pause Time (FCPT) field of the Flow Control

The TX Flow Control Enable (TX_FCEN) bit of the Flow Control Register (FLOW) enables automatic generation of trans-

mit pause frames. When this bit is set, the MAC uses the internal flow control on/off signals generated by the FCT to

trigger pause frame transmission. The FCT signals the MAC whenever the threshold values programmed in the Flow

Control Register (FLOW) are crossed. When the RX FIFO reaches the level set in the Flow Control On Threshold field

of FCT Flow Control Threshold Register (FCT_FLOW), the FCT asserts the internal flow control on signal, which causes

the MAC to transmit a pause frame containing the pause time specified in the Pause Time (FCPT) field of the FLOW

asserts the internal flow control off signal, which causes the MAC to transmit a pause frame with a pause time of zero.

The device will only send another pause frame when the RX FIFO level falls below the Flow Control Off Threshold and

then exceeds the Flow Control On Threshold again.

8.3 Wake On LAN (WOL) Event Detection

8.3.1 OVERVIEW

The following bits of the Wakeup Control and Status Register 1 (WUCSR1), when enabled, may allow a WOL event

detected by the Ethernet MAC to be asserted:

•Perfect DA Frame Received (PFDA_FR)

•Wakeup Frame Enable (WUEN)

•Magic Packet Enable (MPEN)

•Broadcast Wakeup Enable (BCAST_EN)

Similarly, the following bits of the Wakeup Control and Status Register 2 (WUCSR2), when enabled, may allow the

assertion of a WOL event:

•IPv6 TCP SYN Wake Enable (IPV6_TCPSYN_WAKE_EN)

•IPv4 TCP SYN Wake Enable (IPV4_TCPSYN_WAKE_EN)

Whenever Wake-On-LAN Enable (WOL_EN) is set in the Power Management Control Register (PMT_CTL) and at least

one of the previously listed enable bits is set, and the device is in the SUSPEND0 state, the following occurs when

encountering a packet whose characteristics match those specified by the enable bit(s):

• Store frame in RX FIFO when in SUSPEND3

• The appropriate status bits are set in Wakeup Control and Status Register 1 (WUCSR1) and Wakeup Source Reg-

ister (WK_SRC), depending of the settings of the enable bits and the characteristics of the packet.

Note: Half-duplex operation is not supported in 1000 Mbps mode.

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 77

LAN7850

• A wakeup event is signaled to the host.

• The Host sends resume signaling.

• All wakeup status bits are cleared in Wakeup Control and Status Register 1 (WUCSR1) and Wakeup Control and

Status Register 2 (WUCSR2) if the Resume Clears Remote Wakeup Status (RES_CLR_WKP_STS) bit is set in

the Power Management Control Register (PMT_CTL).

• All wakeup enable bits in Wakeup Control and Status Register 1 (WUCSR1) and Wakeup Control and Status Reg-

ister 2 (WUCSR2) are cleared if the Resume Clears Remote Wakeup Enables (RES_CLR_WKP_EN) bit is set in

the Power Management Control Register (PMT_CTL).

• The device transitions to the Normal state.

• The Host then examines data within the device’s registers and memory to determine what occurred.

8.3.2 DETECTION OF WOL EVENTS

The following sections describe, in general terms, each of the WOL events that may be enabled. They assume the fol-

lowing:

•Resume Clears Remote Wakeup Status (RES_CLR_WKP_STS) and Resume Clears Remote Wakeup Enables

(RES_CLR_WKP_EN) bits are NOT set in the Power Management Control Register (PMT_CTL).

8.3.2.1 Perfect DA Detection

Setting the Perfect DA Wakeup Enable (PFDA_EN) bit in the Wakeup Control and Status Register 1 (WUCSR1) and

entering SUSPEND0, SUSPEND1 or SUSPEND3 states places the MAC in the Perfect DA detection mode. In this

mode, normal data reception is disabled, and detection logic within the MAC examines the destination address of each

received frame. When a frame whose destination address matches that specified by the MAC Receive Address High

Received (PFDA_FR) bit in WUCSR1 is set, and remote wakeup is issued. The Host will then resume the device. The

Host may read WUSCR1 and WUSCR2 registers to determine the characteristics of the received packet and the con-

dition(s) that caused the remote wakeup.

The Perfect DA Wakeup Enable (PFDA_EN) bit, as well as all other enable bits in WUCSR1 and WUCSR2 must be

cleared in order to permit the MAC to resume normal receive operation. The Host must also clear all status bits in

WUCSR1 and WUCSR2 before entering the SUSPEND0, SUSPEND1 or SUSPEND3 state to monitor for the next WOL

event.

Note: Multiple status bits may be set in WUCSR and WUCSR2 for the packet. I.e., assume Perfect DA Frame

Received (PFDA_FR) and IPv4 TCP SYN Wake Enable (IPV4_TCPSYN_WAKE_EN) are set. Then Per-

fect DA Frame Received (PFDA_FR) and IPv4 TCP SYN Packet Received (IPV4_TCPSYN_RCD) will be

set when an IPv4 TCP SYN packet matching the parameters set by the SYN IPv4 Source Address Register

(SYN_IPV4_ADDR_SRC), SYN IPv4 Destination Address Register (SYN_IPV4_ADDR_DEST), and SYN

IPv4 TCP Ports Register (SYN_IPV4_TCP_PORTS) is received.

Note: If Resume Clears Remote Wakeup Status (RES_CLR_WKP_STS) is set in Power Management Control

Source Register (WK_SRC) may be consulted.

Note: More than just the Perfect DA Frame Received (PFDA_FR) bit may be set for the packet in WUCSR1 and

WUCSR2, depending on the setting of the enable bits and the packet’s characteristics.

LAN7850

DS00001993D-page 78  2015 - 2017 Microchip Technology Inc.

8.3.2.2 Wakeup Frame Detection

Thirty two programmable wakeup frame filters are supported. Each filter has a 128-bit byte mask that indicates which

bytes of the frame should be compared by the MAC. A CRC-16 is calculated over these bytes. The result is then com-

pared with the filter’s respective CRC-16 to determine if a match exists.

Setting the Wakeup Frame Enable (WUEN) bit in the Wakeup Control and Status Register 1 (WUCSR1), places the

MAC in the Wakeup Frame detection mode. In this mode, normal data reception is disabled, and detection logic within

the MAC examines receive data for the pre-programmed Wakeup Frame patterns. When a wakeup pattern is received,

the Remote Wakeup Frame Received (WUFR) bit in the WUCSR is set, the device places itself in a fully operational

state, and remote wakeup is issued. The Host will then resume the device and read the WUSCR1 and WUCSR2 reg-

isters to determine the condition(s) that caused the remote wakeup.

The Wakeup Frame Enable (WUEN) bit, as well as all other enable bits in WUCSR1 and WUCSR2 must be cleared in

order to permit the MAC to resume normal receive operation. The Host must also clear all status bits in WUCSR1 and

WUCSR2 before entering the SUSPEND0, SUSPEND1 or SUSPEND3 state to monitor for the next WOL event.

Before putting the MAC into the Wakeup Frame detection state, the application program must provide the detection logic

with a list of sample frames and their corresponding byte masks. This information is provided by writing the Wakeup

Filter x Configuration Register (WUF_CFGx), and the Wakeup Filter x Byte Mask Registers (WUF_MASKx) for all

enabled filters. Please refer to the indicated sections for additional information on these registers.

The MAC provides 32 programmable filters that support many different receive packet patterns. Whether or not a filter

is enabled, and the destination address type of an enabled filter, is determined by the Filter Enable and Filter Address

Type fields, respectively, of the Wakeup Filter x Configuration Register (WUF_CFGx).

If remote wakeup mode is enabled, the remote wakeup function receives all frames addressed to the MAC. It then

checks each frame against the enabled filters and recognizes the frame as a remote Wakeup Frame if it passes an

enabled filter’s address filtering and CRC value match.

In order to determine which bytes of the frames should be checked by the CRC module, the MAC uses a programmable

byte mask and a programmable pattern offset for each of the eight supported filters.

The pattern offset defines the location of the first byte that should be checked in the frame. The byte mask is a 128-bit

field that specifies whether or not each of the 128 contiguous bytes within the frame, beginning with the pattern offset,

should be checked. If bit j in the byte mask is set, the detection logic checks byte (pattern offset + j) in the frame, other-

wise, byte (pattern offset + j) is ignored.

At the completion of the CRC-16 checking process, the CRC-16 calculated using the pattern offset and byte mask is

compared to the expected CRC-16 value associated with the filter. If a match occurs, a remote wakeup event is sig-

naled.

The pattern offset and expected CRC-16 for a particular filter is determined by the Filter Pattern Offset and Filter CRC-

16 fields, respectively, of the Wakeup Filter x Configuration Register (WUF_CFGx). The byte mask for a particular filter

is set by the Host by writing the four DWORD mask registers associated with the filter in the Wakeup Filter x Byte Mask

Registers (WUF_MASKx) block.

CRC-16 is calculated as follows:

At the start of a frame, CRC-16 is initialized with the value FFFFh. CRC-16 is updated when the pattern offset and mask

indicate the received byte is part of the checksum calculation. The following algorithm is used to update the CRC-16 at

that time:

Let:

^ denote the exclusive or operator.

Data [7:0] be the received data byte to be included in the checksum.

CRC[15:0] contain the calculated CRC-16 checksum.

F0 … F7 be intermediate results, calculated when a data byte is determined to be part of the CRC-16.

Calculate:

F0 = CRC[15] ^ Data[0]

Note: More than just the Remote Wakeup Frame Received (WUFR) bit may be set for the packet in WUCSR1

and WUCSR2, depending on the setting of the enable bits and the packet’s characteristics.

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 79

LAN7850

F1 = CRC[14] ^ F0 ^ Data[1]

F2 = CRC[13] ^ F1 ^ Data[2]

F3 = CRC[12] ^ F2 ^ Data[3]

F4 = CRC[11] ^ F3 ^ Data[4]

F5 = CRC[10] ^ F4 ^ Data[5]

F6 = CRC[09] ^ F5 ^ Data[6]

F7 = CRC[08] ^ F6 ^ Data[7]

The CRC-16 is updated as follows:

CRC[15] = CRC[7] ^ F7

CRC[14] = CRC[6]

CRC[13] = CRC[5]

CRC[12] = CRC[4]

CRC[11] = CRC[3]

CRC[10] = CRC[2]

CRC[9] = CRC[1] ^ F0

CRC[8] = CRC[0] ^ F1

CRC[7] = F0 ^ F2

CRC[6] = F1 ^ F3

CRC[5] = F2 ^ F4

CRC[4] = F3 ^ F5

CRC[3] = F4 ^ F6

CRC[2] = F5 ^ F7

CRC[1] = F6

CRC[0] = F7

Table 8-1 indicates the cases that produce a wakeup event when the Wakeup Frame Enable (WUEN) bit in the Wakeup

Control and Status Register 1 (WUCSR1) is set. All other cases do not generate a wakeup event.

Note 8-1 As determined by the Filter Enable bit of the respective Wakeup Filter x Configuration Register

(WUF_CFGx).

Note 8-2 CRC matches Filter x CRC-16, as determined by the Filter CRC-16 field of the respective Wakeup

Filter x Configuration Register (WUF_CFGx).

Note 8-3 As determined by the Filter Address Type field of the Wakeup Filter x Configuration Register

(WUF_CFGx).

TABLE 8-1: WAKEUP GENERATION CASES

FILTER

ENABLED

(Note 8-1)

CRC

MATCH

(Note 8-2)

PASS

REGULAR

RECEIVE

FILTER

ADDRESS

TYPE

(Note 8-3) WAKEUP PACKET TYPE SUPPORTED

Yes Yes Yes Multicast

(=10b)

Multicast

Yes Yes Yes Unicast

(=00b)

Unicast

Yes Yes Yes Passed

Receive

Filter

(=x1b)

Broadcast, Multicast, Unicast

LAN7850

DS00001993D-page 80  2015 - 2017 Microchip Technology Inc.

8.3.2.3 Magic Packet Detection

Setting the Magic Packet Enable (MPEN) bit in the Wakeup Control and Status Register 1 (WUCSR1) places the MAC

in the “Magic Packet” detection mode. In this mode, normal data reception is disabled, and detection logic within the

MAC examines receive data for a Magic Packet.

When a Magic Packet is received, the Magic Packet Received (MPR) bit in the WUCSR is set, the device places itself

in a fully operational state, and remote wakeup is issued. The Host will then resume the device and read the WUSCR1

and WUCSR2 registers to determine the condition(s) that caused the remote wakeup.

The Magic Packet Enable (MPEN) bit, as well as all other enable bits in WUCSR1 and WUCSR2 must be cleared in

order to permit the MAC to resume normal receive operation. The Host must also clear all status bits in WUCSR1 and

WUCSR2 before entering the SUSPEND0, SUSPEND1 or SUSPEND3 state to monitor for the next WOL event.

In Magic Packet mode, logic within the MAC constantly monitors each frame addressed to the node for a specific Magic

Packet pattern. It checks packets with the MAC’s address or a multicast address (which includes the broadcast address)

to meet the Magic Packet requirement.

The MAC checks each received frame for the pattern 48‘hFF_FF_FF_FF_FF_FF synchronization stream after the des-

tination and source address field. Then the MAC inspects the frame for 16 repetitions of the MAC address without any

breaks or interruptions. In case of a break in the 16 address repetitions, the MAC scans for the

48‘hFF_FF_FF_FF_FF_FF pattern again in the incoming frame.

The 16 repetitions may be anywhere in the frame but must be preceded by the synchronization stream. The device will

also accept a multicast frame, as long as it detects the 16 duplications of the MAC address. If the MAC address of a

node is 00h 11h 22h 33h 44h 55h, then the MAC scans for the following data sequence in an Ethernet frame:

Destination Address Source Address ……………FF FF FF FF FF FF

00 11 22 33 44 55 00 11 22 33 44 55 00 11 22 33 44 55 00 11 22 33 44 55

…FCS

8.3.2.4 Broadcast Detection

Setting the Broadcast Wakeup Enable (BCAST_EN) bit in the Wakeup Control and Status Register 1 (WUCSR1) and

entering SUSPEND0, SUSPEND1 or SUSPEND3 states places the MAC in the Broadcast detection mode. In this

mode, normal data reception is disabled, and detection logic within the MAC examines the destination address of each

received frame. When a frame whose destination address is FF FF FF FF FF FF is received, the Broadcast Frame

Received (BCAST_FR) bit in the WUCSR is set, the device places itself in a fully operational state, and remote wakeup

is issued. The Host will then resume the device and read the WUSCR1 and WUCSR2 registers to determine the con-

dition(s) that caused the remote wakeup.

Note: x indicates “don’t care”.

Note: More than just the Magic Packet Received (MPR) bit may be set for the packet in WUCSR1 and WUCSR2,

depending on the setting of the enable bits and the packet’s characteristics.

Note: The MAC’s address is specified by the MAC Receive Address High Register (RX_ADDRH) and the MAC

Receive Address Low Register (RX_ADDRL).

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 81

LAN7850

The Broadcast Wakeup Enable (BCAST_EN) bit, as well as all other enable bits in WUCSR1 and WUCSR2 must be

cleared in order to permit the MAC to resume normal receive operation. The Host must also clear all status bits in

WUCSR1 and WUCSR2 before entering the SUSPEND0, SUSPEND1 or SUSPEND3 states to monitor for the next

WOL event.

8.3.3 TCP SYN DETECTION

The device supports wakeup on receiving a TCP SYN packet over a IPv4 or a IPv6 frame. The Wakeup Control and

Status Register 2 (WUCSR2) contains the bits that control this and other Windows 7 Power Management features. Two

sets of registers are used to control TCP SYN Detection - one set for IPv4 and another for IPv6. Their use is discussed

in the following sections.

The following sections describe, in general terms, each of the TCP SYN events that may be enabled. They assume that

Resume Clears Remote Wakeup Status (RES_CLR_WKP_STS) and Resume Clears Remote Wakeup Enables (RES_-

CLR_WKP_EN) bits are NOT set in the Power Management Control Register (PMT_CTL).

8.3.3.1 IPv4 TCP SYN Detection

The following registers are dedicated for use in detecting a TCP SYN packet within an IPv4 frame:

•SYN IPv4 Source Address Register (SYN_IPV4_ADDR_SRC)

•SYN IPv4 Destination Address Register (SYN_IPV4_ADDR_DEST)

•SYN IPv4 TCP Ports Register (SYN_IPV4_TCP_PORTS)

IPv4 TCP SYN detection occurs when the IPv4 TCP SYN Wake Enable (IPV4_TCPSYN_WAKE_EN) bit is set in

Wakeup Control and Status Register 2 (WUCSR2) and the device is in the SUSPEND0, SUSPEND1 or SUSPEND3

states. When these conditions are met, logic within the MAC will process IPv4 frames whose destination address is the

device’s MAC address, a multi-cast address, or the broadcast address as follows:

A check is made for a TCP protocol match within the IPv4 header. Valid TCP packets whose SYN bit is asserted, having

an IPv4 header whose source address and destination address match those specified in the SYN IPv4 Source Address

respectively, and whose source port and destination port match those specified by the SYN IPv4 TCP Ports Register

(SYN_IPV4_TCP_PORTS), will cause a wakeup. Upon detecting a wakeup condition, the IPv4 TCP SYN Packet

Received (IPV4_TCPSYN_RCD) bit is set in WUSCR2, the device places itself in a fully operational state, and remote

wakeup is issued.

The Host will then resume the device and read the WUSCR1 and WUCSR2 registers to determine the condition(s) that

caused the remote wakeup.

Note: More than just the Broadcast Frame Received (BCAST_FR) bit may be set for the packet in WUCSR1 and

WUCSR2, depending on the setting of the enable bits, the packet’s characteristics, and the programming

of the MAC Receive Address High Register (RX_ADDRH) and the MAC Receive Address Low Register

(RX_ADDRL). I.e., if, for some reason, RX_ADDRH and RX_ADDRL retain their default values, then

Broadcast Frame Received (BCAST_FR), as well as Perfect DA Frame Received (PFDA_FR) would be

set on reception of a Broadcast frame.

Note: TCP SYN Detection should be enabled for use when the device is being programmed to enter the SUS-

PEND0, SUSPEND1 or SUSPEND3 states, in anticipation of generating a WOL event. Its use in any state

other than SUSPEND0, SUSPEND1 or SUSPEND3, may result in untoward operation and unexpected

results.

Note: The registers can be set to force a match to occur with the field its contents are being compared to. Please

refer to the register definition for details.

LAN7850

DS00001993D-page 82  2015 - 2017 Microchip Technology Inc.

The IPv4 TCP SYN Wake Enable (IPV4_TCPSYN_WAKE_EN) bit, as well as all other enable bits in WUCSR1 and

WUCSR2 must be cleared in order to permit the MAC to resume normal receive operation. The Host must also clear all

status bits in WUCSR and WUCSR2 before entering the SUSPEND0, SUSPEND1 or SUSPEND3 states to monitor for

the next WOL event.

8.3.4 IPV6 TCP SYN DETECTION

The following registers are dedicated for use in detecting a TCP SYN packet within an IPv6 frame:

•SYN IPv6 Source Address Register (SYN_IPV6_ADDR_SRC)

•SYN IPv6 Destination Address Register (SYN_IPV6_ADDR_DEST)

•SYN IPv6 TCP Ports Register (SYN_IPV6_TCP_PORTS)

IPv6 TCP SYN detection occurs when the IPv6 TCP SYN Wake Enable (IPV6_TCPSYN_WAKE_EN) bit is set in

WUCSR2 and the device is in the SUSPEND0, SUSPEND1 or SUSPEND3 states. When these conditions are met, logic

within the MAC will process IPv6 frames whose destination address is the device’s MAC address, a multi-cast address,

or the broadcast address as follows:

A check is made for a TCP protocol match within the IPv6 header (or an extension header). Valid TCP packets whose

SYN bit is asserted, having an IPv6 header whose source address and destination address match those specified in

the SYN IPv6 Source Address Register (SYN_IPV6_ADDR_SRC) and the SYN IPv6 Destination Address Register

(SYN_IPV6_ADDR_DEST), respectively, and whose TCP ports in the IPv6 payload (TCP packet) match those specified

by the SYN IPv6 TCP Ports Register (SYN_IPV6_TCP_PORTS), will cause a wakeup. Upon detecting a wakeup con-

dition, the IPv6 TCP SYN Packet Received (IPV6_TCPSYN_RCD) bit is set in WUSCR2, the device places itself in a

fully operational state, and remote wakeup is issued.

The Host will then resume the device and read the WUSCR1 and WUCSR2 registers to determine the condition(s) that

caused the remote wakeup.

The IPv6 TCP SYN Wake Enable (IPV6_TCPSYN_WAKE_EN) bit, as well as all other enable bits in WUCSR1 and

WUCSR2 must be cleared in order to permit the MAC to resume normal receive operation. The Host must also clear all

status bits in WUCSR1 and WUCSR2 before entering the SUSPEND0, SUSPEND1 or SUSPEND3 states to monitor

for the next WOL event.

Note: More than just the IPv4 TCP SYN Packet Received (IPV4_TCPSYN_RCD) bit may be set for the packet

in WUCSR1 and WUCSR2, depending on the setting of the enable bits and the packet’s characteristics.

Note: The IPv4 TCP SYN packet must be valid in order for packet detection to be signaled. The header check-

sum, TCP checksum, and FCS are calculated and all must agree with the packet contents, in order for the

packet to be considered for detection analysis.

Note: The registers can be set to force a match to occur with the protocol field its contents is being compared to.

Please refer to the register definition for details.

Note: More than just the IPv6 TCP SYN Packet Received (IPV6_TCPSYN_RCD) bit may be set for the packet

in WUCSR1 and WUCSR2, depending on the setting of the enable bits and the packet’s characteristics.

Note: The IPv6 TCP SYN packet must be valid in order for packet detection to be signaled. The TCP checksum

and FCS are calculated and must agree with the packet contents, in order for the packet to be considered

for detection analysis.

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 83

LAN7850

8.4 Always on Always Connected (AOAC)

This device supports the Connected Standby state of Microsoft’s instant-on and always-connected power model, similar

to smart-phone devices. The intent of Connected Standby is to enable a PC to resume from sleep extremely quickly -

typically less than 500 milliseconds. The performance of a resume from Connected Standby is almost always faster than

the traditional Sleep (S3) state and significantly faster than a resume from Hibernate (S4) or Shutdown (S5).

ENGINEERING NOTE: AOAC and Connected Standby were introduced for Windows 8.X operating systems.

In Connected Standby certain networking tasks are offloaded from the host CPU by the device to conserve system

power and to enable the network to maintain basic L2 connectivity. For this device, ARP and NS offloads are enabled

to minimize host wake ups. Additionally, the device is configured to detect a wakeup event and upon detection awakens

the CPU.

In the case the wake event is a wakeup frame, it is stored in the FCT RX FIFO. This is required to maintain higher layer

protocol connections and enable the host software to determine the cause of the wake up. Any frames received after

the wakeup event are also stored in the FCT RX FIFO. This coalescing of packets allows windows to process batches

of packets in a single pass without potentially breaking any protocols.

The following wake events are supported in Connected Standby.

• WOL (Wakeup Frame, Magic Packet)

• Broadcast Frame

• Perfect DA

• Link Status Connected

• Link Status Disconnected

• GPIO Assertion

• TCP SYN

The steps for AOAC support are as follows.

1. An extended period of time expires with out an Ethernet packet or transmission or reception. The timescale is

typically in the order of seconds.

2. Driver enables SUSPEND3 in Power Management Control Register (PMT_CTL).

3. Driver enables NS Offload and ARP Offload.

4. Driver configures desired wakeup events.

5. Driver enables wakeup packet storage in FCT RX FIFO via the Store Wakeup Frame (STORE_WAKE) bit in the

Wakeup Control and Status Register 1 (WUCSR1).

6. Device is suspended by host.

8.5 Neighbor Solicitation (NS) Offload

NS Offload is a power management feature that permits the device to respond to a NS request by generating and trans-

mitting the required NA response packet. It will not result in the generation of a wake event.

The following registers are used to facilitate NS offload:

•NSx IPv6 Destination Address Register (NSx_IPV6_ADDR_DEST)

•NSx IPv6 Source Address Register (NSx_IPV6_ADDR_SRC)

•NSx ICMPv6 Address 0 Register (NSx_ICMPV6_ADDR0)

•NSx ICMPv6 Address 1 Register (NSx_ICMPV6_ADDR1)

Note: For all registers, 0<=x<=1

Note: The registers can be set to force a match to occur with the protocol field its contents is being compared to.

Please refer to the register definition for details.

LAN7850

DS00001993D-page 84  2015 - 2017 Microchip Technology Inc.

These registers are used when the NS Offload Enable (NS_OFFLOAD_EN) bit is set in Wakeup Control and Status

address matches either the device’s MAC address, a multi-cast address, or is the broadcast address. Frames not meet-

ing this criteria shall be ignored.

The headers of all IPv6 frames matching the aforementioned criteria are further checked as follows. IPv6 DA is com-

pared to NSx IPv6 Destination Address Register (NSx_IPV6_ADDR_DEST) and NSx ICMPv6 Address 0 Register

(NSx_ICMPV6_ADDR0) and NSx ICMPv6 Address 1 Register (NSx_ICMPV6_ADDR1). One of the three compares

must match. IPv6 SA is compared to NSx IPv6 Source Address Register (NSx_IPV6_ADDR_SRC).

When NSx IPv6 Source Address Register (NSx_IPV6_ADDR_SRC) is set to 0h, the IPv6 SA check is ignored. A match

is yielded.

In the event that the IPv6 header destination address is a solicited node multicast address (i.e. it has a prefix that

matches FF02.1:FF00:0/104), only the upper three bytes (NSx_IPv6_ADDR_DEST_3 [127:104]) of NSx IPv6 Destina-

tion Address Register (NSx_IPV6_ADDR_DEST) are compared against the last 24 bits of the IPv6 header destination

address.

If both IPv6 DA and SA checks pass, and the Next Header field of the IPv6 header (or any extension headers) specify

ICMPv6 (58), then a check is made to determine whether an NS (Neighbor Solicitation) request is being made (ICMP

type = 135 and code = 0 within the ICMPv6 header).

If so, the target address specified in the NS request is compared to the addresses contained in the NSx ICMPv6 Address

0 Register (NSx_ICMPV6_ADDR0) and NSx ICMPv6 Address 1 Register (NSx_ICMPV6_ADDR1). If a match occurs

on either comparison, and the ICMPv6 checksum is good, and no other errors occurred in the frame, then the MAC shall

transmit an NA response frame to the sender.

The NS frame must be validated per the checks defined in section 7.1.1 of RFC 4861. Frames that fail the validation

checks are discarded.

NA response frames have the following characteristics:

Frame header:

- DA = SA from frame header of the NS packet

- SA = device’s MAC address

- Type = 86DDh

IPv6 header:

- SA = When NA SA Select (NA_SA_SEL) of Wakeup Control and Status Register 2 (WUCSR2) is cleared, the

Target address from the NS packet is used. When set, the value in NSx IPv6 Destination Address Register

(NSx_IPV6_ADDR_DEST) is used.

- DA = SA of NS packet, if specified. If NS packet contained an unspecified address (0::0) in its IPv6 SA, then

DA = FF02:0:0:0:0:0:0:1

- Hop limit = 255

ICMPv6:

- Type = 136

- Code = 0

- Checksum = set to the checksum - 16-bit 1’s complement of the 1’s complement sum calculated over the

entire message starting with a “pseudo-header” of the IPv6 header fields (next header is 58)

- Router flag = 0

- Solicited flag = 1 if Destination Address is not equal to FF02:0::1, otherwise 0

- Override flag = 1

- Reserved = 0 (This is a 29 bit field)

- Target address = target address from the NS packet

- Option = device’s MAC address (same as frame header)

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 85

LAN7850

8.6 ARP Offload

ARP Offload is a power management feature that permits the device to respond to an ARP request by generating and

transmitting the required response packet.

The following registers are used to facilitate ARP offload:

•ARP Sender Protocol Address Register (ARP_SPA)

•ARP Target Protocol Address Register (ARP_TPA)

These registers are used when the ARP Offload Enable (ARP_OFFLOAD_EN) bit is set in WUCSR2. When enabled,

logic within the MAC will examine the frame type of all received Ethernet frames. ARP frames (those having a frame

type of 0806h) whose destination address matches the device’s MAC address or is the broadcast address will further

be examined. Frames that are not ARP frames or frames that are ARP frames, but whose destination address did not

fit the selection criteria, will be ignored.

The following fields of the ARP header are checked to ensure they are set to the indicated values. if a mismatch occurs,

the frame is ignored.

• Hardware Type (HTYPE) - 0x0001 for Ethernet

• Protocol Type (PTYPE) - 0x0800 for IPv4

• Hardware Address Length (HLEN) - 0x06 for Ethernet

• Protocol Address Length (PLEN) - 0x04 for IPv4

• Opcode (OP) - 0x0001 for Request

The contents of the ARP Sender Protocol Address Register (ARP_SPA) and ARP Target Protocol Address Register

(ARP_TPA) are compared to the SPA and TPA fields, respectively, of the ARP message. If the contents of both registers

match the contents of the message, then the MAC TX is signaled to transmit an ARP response frame to the sender.

ARP response frames have the following characteristics:

Frame header:

- DA = SA from frame header of the ARP packet

- SA = device’s MAC address

- Type = 0806h

ARP message:

- Hardware type = 1

- Protocol type = 0800h

- Hardware length = 6

- Protocol length = 4

- Sender HA = device’s MAC address

- Sender IP = TPA field from the ARP request packet

- Target HA = SHA field from the ARP request packet

- Target IP = SPA field from the ARP request packet

Note: The IPv6 TCP SYN Packet Received (IPV6_TCPSYN_RCD) bit in Wakeup Control and Status Register 2

(WUCSR2) is set whenever a NS packet is received during the time interval between NS Offload Enable

(NS_OFFLOAD_EN) being set and subsequently cleared. This bit, and all other status bits contained in

Wakeup Control and Status Register 1 (WUCSR1) and Wakeup Control and Status Register 2 (WUCSR2)

should be cleared prior to entering a SUSPEND state. NS Packet Received (NS_RCD) will be automati-

cally cleared when exiting a SUSPEND state whenever the Resume Clears Remote Wakeup Status

(RES_CLR_WKP_STS) bit is set in the Power Management Control Register (PMT_CTL).

Note: The registers can be set to force a match to occur with the protocol field its contents is being compared to.

Please refer to the register definition for details.

LAN7850

DS00001993D-page 86  2015 - 2017 Microchip Technology Inc.

8.7 Automatic Speed and Duplex Detection

The device permits manual or automatic control of speed and duplex operation.

The Automatic Speed Detection (ASD) bit in the MAC Control Register (MAC_CR) controls whether or not the MAC

operational speed is determined automatically or is manually set. When ASD is set, the MAC ignores the setting of the

MAC Configuration (CFG) field of the MAC Control Register (MAC_CR) and automatically determines the speed of

operation. The MAC samples an internal receive clock signal to accomplish speed detection and reports the last deter-

mined speed via the MAC Configuration (CFG) field. When ASD is zero, the setting of the MAC Configuration (CFG)

field determines operational speed.

The Automatic Duplex Detection (ADD) bit in the MAC Control Register (MAC_CR) controls whether or not the MAC

operates in manual or automatic duplex mode of operation. When this bit is set, the MAC ignores the setting of the

Duplex Mode (DPX) bit in the MAC Control Register (MAC_CR) and automatically determines the duplex operational

mode. The MAC uses the PHY status signal to accomplish mode detection and reports the last determined status via

the Duplex Mode (DPX) bit. When ADD is zero, the setting of the Duplex Mode (DPX) bit determines Duplex operation.

See Section 9.1, "Category 5 Twisted Pair Media Interface" for additional information.

On loss of SYNC, the MAC will commence automatic speed and/or duplex detection, depending on the setting of ASD/

ADD.

8.8 Loopback Operation

The following Loopback modes are available:

• PHY Loopback Mode

• MAC Internal Loopback Mode

This mode is configured via the Internal Loopback Operation Mode (INT_LOOP) bit of the MAC Control Register

(MAC_CR). It is only valid in full-duplex mode of operation. In this loopback mode, the TX frame is received by the Inter-

nal GMII interface and is sent back to the MAC without being sent to the PHY.

Note: The ARP Packet Received (ARP_RCD) bit in WUCSR2 is set whenever a ARP request is received during

the time interval between ARP Offload Enable (ARP_OFFLOAD_EN) being set and subsequently cleared.

This bit, and all other status bits contained in WUCSR1 and WUCSR2 should be cleared prior to entering

a SUSPEND state. ARP Packet Received (ARP_RCD) will be automatically cleared when exiting a SUS-

PEND state whenever the Resume Clears Remote Wakeup Status (RES_CLR_WKP_STS) bit is set in the

Power Management Control Register (PMT_CTL).

Note: The ARP Offload Enable (ARP_OFFLOAD_EN) bit of the WUCSR2 register must be cleared in order for

the MAC to resume normal receive and transmit operation. Failure to clear this bit and all other enable bits

contained in WUCSR1 and WUCSR2 upon returning to the Normal state, or setting this bit during normal

operation, will result in untoward operation and unexpected results.

FIGURE 8-1: LOOPBACK OPERATIONAL MODES

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 87

LAN7850

8.9 802.3az EEE Support

The device supports Energy Efficient Ethernet as defined in revision IEEE 802.3az-2012 of the standard. EEE support

is enabled by the Energy Efficient Ethernet Enable (EEEEN) bit of the MAC Control Register (MAC_CR).

8.9.1 TX LPI GENERATION

The process of when the MAC should indicate LPI requests to the PHY is divided into two sections.

First is the concept of the “Client”, which is basically any source of data that the MAC needs to transmit. This includes

packet data via the TX FCT, pause frames request via the RX FCT and ARP and NS offload frames internally generated

by the MAC due to the reception of certain frames.

The second section is the MAC low level FSM, which includes the concepts of IDLE, DEFERRAL, IFG, PREAMBLE and

DATA / FCS.

8.9.1.1 Client LPI Requests to MAC

The Client to MAC LPI request process is shown in Figure 8-2.

When the TX FCT is empty for a time (in microseconds) specified in EEE TX LPI Request Delay Count Register

(EEE_TX_LPI_REQUEST_DELAY_CNT) a TX LPI request is asserted to the MAC. This is managed by the internal FCT

TX Empty Timer. A setting of 0 us is possible for this time. If the TX FCT becomes not empty while the timer is running,

the timer will reset (i.e. empty time is not cumulative). Once TX LPI is requested and the TX FCT becomes not empty,

the TX LPI request is negated. The Client shall return to waiting for the TX FCT to be empty. Note that it is conceivable

for the TX LPI request to the MAC to only be asserted for a single clock cycle.

The TX LPI request can optionally be automatically removed after the time specified in the EEE TX LPI Automatic

Removal Delay Register (EEE_TX_LPI_AUTO_REMOVAL_DELAY) in anticipation of periodic transmissions. This func-

tion is enabled with the Energy Efficient Ethernet TX LPI Automatic Removal Enable (EEE_TX_LPI_AUTO_REMOV-

AL_EN) bit. The TX FCT Empty timer is reset and the client returns to waiting for the TX FCT to be empty for the request

delay time as above.

TX LPI requests are asserted only if the Energy Efficient Ethernet Enable (EEEEN) bit is set in the MAC Control Register

(MAC_CR), the current speed is 100 Mbps or 1000 Mbps, the current duplex is full and the auto-negotiation result indi-

cates that both the local and partner device support EEE at the current operating speed. In order to prevent an unstable

link condition, the PHY link status also must indicate “up” for one second before LPI is requested.

FIGURE 8-2: CLIENT LPI REQUEST GENERATION

LAN7850

DS00001993D-page 88  2015 - 2017 Microchip Technology Inc.

TX LPI requests are asserted even if the Transmitter Enable (TXEN) bit in the MAC Transmit Register (MAC_TX) is

cleared.

When TX LPI is requested to the MAC, the Energy Efficient Ethernet Start TX Low Power Interrupt (EEE_START_TX-

_LPI_INT) bit will be set. This bit may generate a USB interrupt if Energy Efficient Ethernet Start TX Low Power Enable

(EEE_START_TX_LPI_EN) is set.

When the TX LPI request is de-asserted, due to the expiration of the above EEE TX LPI Automatic Removal Delay Reg-

ister (EEE_TX_LPI_AUTO_REMOVAL_DELAY) timer, the Energy Efficient Ethernet Stop TX Low Power Interrupt

(EEE_STOP_TX_LPI_INT) bit is set. This bit may then generate a USB interrupt if Energy Efficient Ethernet Stop TX

Low Power Enable (EEE_STOP_TX_LPI_EN) is set.

Also when the TX LPI request is de-asserted due to the same automatic removal, the Energy Efficient Ethernet TX Wake

(EEE_TX_WAKE) bit is set if Energy Efficient Ethernet TX Wake Enable (EEE_TX_WAKE_EN) is set. Energy Efficient

Ethernet TX Wake (EEE_TX_WAKE) being set causes EEE WAKE-UP Status (EEE_WUPS) to set. EEE WAKE-UP

Status (EEE_WUPS), in turn, may generate a USB remote wake-up event if EEE WAKE-UP Enable (EEE_WAKE-

UP_EN) is set. EEE TX Wake is required to operate during the SUSPEND3 Power state, however the hardware should

not intentionally enforce the power state mapping since it is left to the S/W driver to properly match wake events and

power states.

8.9.1.1.1 Flow Control, ARP Response and NS Response Packet Interaction

It is possible that a pause frame (automatically generated based on the RX FCT levels or RX FCT overflow or manual

generated via the FORCE_FC bit in the FLOW register) or an ARP or NS response packet needs to be transmitted while

waiting for the TX FCT empty timer to expire. When such packets are necessary, the TX FCT empty timer is not restart

or paused. If such a packet is started while waiting for TX FCT empty timer but finishes following the wait time, TX LPI

is requested following the packet (i.e. the LPI request is delayed). If the TX FCT becomes not empty while the packet

is being transmitted, the TX FCT empty timer is reset, as normally would happen, and TX LPI is not requested.

It is also possible that a pause frame or an ARP or NS response packet needs to be transmitted while the TX LPI request

is asserted. When such packets are necessary, the TX LPI request is de-asserted and the packet is presented to the

MAC for transmission. The MAC, as described below, will defer until the appropriate wake timer has expired before

transmitting the packet. Once the packet is sent to the MAC, TX LPI is immediately reasserted, assuming that the FCT

empty timer is still expired and that the EEE TX LPI Automatic Removal Delay Register (EEE_TX_LPI_AUTO_REMOV-

AL_DELAY) timer has not expired. The MAC, as described below, will finish the packet transmission before signaling

LPI to the PHY

Removal of the LPI request, due to flow control or ARP or NS response packets does, not reset the FCT empty timer

nor does it reset or pause the EEE TX LPI Automatic Removal Delay Register (EEE_TX_LPI_AUTO_REMOVAL_DE-

LAY) timer.

8.9.1.2 MAC LPI Request to PHY

The MAC will always finish the current packet before signaling TX LPI to the PHY. It is possible that the TX LPI request

from the Client is asserted and de-asserted during a packet. This will not result in a TX LPI request to the PHY nor will

it trigger the wake timer described below.

The MAC will generate TX LPI requests to the PHY even if the Transmitter Enable (TXEN) bit in the MAC Transmit Reg-

ister (MAC_TX) is cleared.

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 89

LAN7850

802.3az specifies the usage of a simplified full duplex MAC with carrier sense deferral. Basically this means that once

the TX LPI request to the PHY is de-asserted, the MAC will defer the time specified in EEE Time Wait TX System Reg-

ister (EEE_TW_TX_SYS) in addition to the normal IPG before sending a frame. This is shown in Figure 8-3.

In part A of the figure, a carrier indicator is set when the TX LPI request to the PHY is asserted. The wake timer (tw_-

timer) is triggered when the TX LPI request to the PHY is de-asserted and once the wake timer is satisfied, the carrier

indicator is cleared. Note that there are separate TX wait values depending on the speed of operation.

Part B of the figure shows that a deferring indicator is set when either a frame is transmitted or the carrier indicator is

active. Once the frame transmission is finished or (logically an “and”) the carrier indicator is cleared, the IFG timer is

triggered and once the IFG timer is satisfied, the deferring indicator is cleared.

Part C of the figure shows that the MAC transmitter waits for the clearing of the deferring indicator before transmitting

a frame. This is unchanged.

8.9.1.2.1 Selecting the source of transmit data Following wake

Currently, when presented with a simultaneous request to transmit FCT data, ARP or NS responses or pause packets,

the MAC prioritizes pause packets over the other sources. In order to minimize the impact of the wake time on the

latency of transmitting a pause packet, the choice of data source must not be made until the expiration of the wake time.

As an example, assume that during the TX LPI, a maximum size transmit packet is written into the TX FCT. Also assume

that during the wake time, the RX FCT FIFO level reaches the pause threshold and a request is made for a pause packet

to be transmitted. At the expiration of the wake time, if the packet from the TX FCT was selected and transmitted, the

eventual pause packet would have waited the wake time portion plus the maximum packet transmit time. The additional

of the wake time may not have been accounted for in the RX FCT threshold level setting and an overflow might occur

as a result. To alleviate this issue, the pause packet should be selected at the expiration of the wake time.

8.9.1.2.2 Halting GMII TX Clock

Once the TX LPI request is asserted, the MAC, optionally based on the Energy Efficient Ethernet TX Clock Stop Enable

(EEE_TX_CLK_STOP_EN) bit in the MAC Control Register (MAC_CR), may halt the GMII GTX_CLK output. The MAC

provides at least 9 clock cycles of GTX_CLK following the assertion of the TX LPI request before halting the clock. The

MAC provides at least 1 clock cycle of GTX_CLK before the de-assertion of the TX LPI request.

8.9.1.2.3 TX LPI Counters

The MAC maintains a counter, EEE TX LPI Transitions, that counts the number of times that TX LPI request to the PHY

changes from de-asserted to asserted. The counter is not writable and does not clear on read.

The MAC maintains a counter, EEE TX LPI Time, that counts (in microseconds) the amount of time that TX LPI is

asserted. Note that this counter does not include the time specified in the EEE Time Wait TX System Register

(EEE_TW_TX_SYS). The counter is not writable and does not clear on read.

Both counters are required to operate during SUSPEND0, SUSPEND3 and Normal Configured Power states.

FIGURE 8-3: TX LPI WAKE TIMER

LAN7850

DS00001993D-page 90  2015 - 2017 Microchip Technology Inc.

8.9.2 RX LPI DETECTION

In order to provide robustness, RX LPI is seen active from the PHY for 3 RX clocks in order to be considered valid active

and is seen inactive from the PHY for 4 RX clocks in order to be considered valid inactive.

8.9.2.1 LPI Affect on Automatic Speed Detection

It is possible for the PHY to halt RX_CLK after indicating LPI but at least 9 RX clocks of LPI will occur before the RX_CLK

is stopped. When RX_CLK is restarted, due to wake signaling, at least 1 RX clock of RX LPI will occur before the PHY

indicates normal IDLE.

8.9.2.2 Decoding LPI

The MAC will decode the start of the RX LPI indication and set the Energy Efficient Ethernet RX Low Power Interrupt

(EEE_RX_LPI_INT) bit. This bit may generate a USB interrupt if Energy Efficient Ethernet RX Low Power Enable

(EEE_RX_LPI_EN) is set.

The MAC will decode the end of the RX LPI indication and, if Energy Efficient Ethernet RX Wake Enable (EEE_RX-

_WAKE_EN) is set, the MAC will set Energy Efficient Ethernet RX Wake (EEE_RX_WAKE). Energy Efficient Ethernet

RX Wake (EEE_RX_WAKE) being set causes EEE WAKE-UP Status (EEE_WUPS) to set. EEE WAKE-UP Status

(EEE_WUPS), in turn, may generate a USB remote wake-up event if EEE WAKE-UP Enable (EEE_WAKEUP_EN) is

set. EEE RX Wake is required to operate during SUSPEND0 and SUSPEND3 Power states, however the hardware will

not intentionally enforce the power state mapping since it is left to the software driver to properly match wake events

and power states.

The MAC will decode the LPI indication only when the Energy Efficient Ethernet Enable (EEEEN) bit is set in the MAC

Control Register (MAC_CR), the current speed is 100Mbs or 1000Mbs, the current duplex is full and the auto-negotia-

tion result indicates that both the local and partner device supports EEE at the current operating speed. In order to pre-

vent an unstable link condition, the PHY link status also must indicate “up” for one second before LPI is decoded.

The MAC will decode the LPI indication even if Receiver Enable (RXEN) in the MAC Receive Register (MAC_RX) is

cleared.

8.9.2.3 RX LPI Counters

The MAC maintains a counter, EEE RX LPI Transitions, that counts the number of times that the LPI indication from the

PHY changes from de-asserted to asserted. The counter is not writable and does not clear on read.

The MAC maintains a counter, EEE RX LPI Time, that counts (in microseconds) the amount of time that the PHY indi-

cates LPI. The counter is not writable and does not clear on read.

Both counters are required to operate during SUSPEND0, SUSPEND3 and Normal Configured Power states.

8.10 MAC Reset Watchdog Timer

A portion of the MAC operates on clocks generated by the Ethernet PHY. During a PHY reset event, this portion of the

MAC is designed to not be taken out of reset until the PHY clocks are operational, such that the respective MAC resets

can be de-asserted synchronously. In the event of an error condition in which the MAC’s RX and TX clocks are not

enabled, a watchdog timer is provided to detect this condition. The duration of the timer is 8 ms.

The below scenarios utilize the watchdog timer:

• System level reset events.

•PHY Reset (PHY_RST) results in resetting the portion of the MAC operating on the PHY receive and transmit

clocks and therefore they also enable the watchdog timer.

• The Ethernet PHY is held in reset while in SUSPEND2. If the device transitions to Normal-Configured, the PHY

must be taken out of reset as well as the affected portions of the MAC. This likewise enables the watchdog timer.

The expiration of the timer causes MAC Reset Time Out (MACRTO_INT) in Interrupt Status Register (INT_STS) to

assert.

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 91

LAN7850

9.0 GIGABIT ETHERNET PHY (GPHY)

The device incorporates a low-power Gigabit Ethernet PHY (GPHY) transceiver that is fully compliant with the IEEE

802.3, 802.3u, 802.3ab, and 802.3az (Energy Efficient Ethernet) standards. It provides a low electromagnetic interfer-

ence (EMI) line driver, and integrated line side termination resistors that conserve both power and printed circuit board

(PCB) space.

The mixed signal and digital signal processing (DSP) architecture of the Ethernet PHY assures robust performance

even under less-than-favorable environmental conditions. It supports both half-duplex and full-duplex 10BASE-T,

100BASE-TX, and 1000BASE-T communication speeds over Category 5 (Cat5) unshielded twisted pair (UTP) cable at

distances greater than 100m, displaying excellent tolerance to NEXT, FEXT, echo, and other types of ambient environ-

ment and system electronic noise. The Ethernet PHY implements auto-negotiation to automatically determine the best

possible speed and duplex mode of operation. HP Auto-MDIX support allows the use of direct connect or cross-over

LAN cables.

The Ethernet PHY supports Wake on LAN (WoL), providing a mechanism to trigger an interrupt upon reception of a

perfect DA, broadcast, magic packet, or wakeup frame. This feature allows filtering of packets at the PHY layer, without

requiring MAC intervention. Additionally, the Ethernet PHY supports cable diagnostics which allow the device to identify

opens/shorts and their location on the cable via vendor-specific registers.

Per IEEE 802.3-2005 standards, all digital interface pins are tolerant to 3.6V. Additional power savings can be achieved

by utilizing the integrated Energy Efficient Ethernet (EEE) function and Enhanced ActiPHY power saving mode, result-

ing in significant power savings during low link utilizations.

The Ethernet PHY is configurable via the Ethernet PHY Control and Status Registers. These registers are accessed

indirectly through the Ethernet MAC via the MII Access Register (MII_ACCESS) and MII Data Register (MII_DATA).

9.1 Category 5 Twisted Pair Media Interface

9.1.1 VOLTAGE-MODE LINE DRIVER

The Ethernet PHY uses a patented voltage-mode line driver that allows it to fully integrate the series termination resis-

tors (required to connect the PHY’s Category 5 interface to an external 1:1 transformer). Also, the interface does not

require the user to place an external voltage on the center tap of the magnetic.

9.1.2 CATEGORY 5 AUTO-NEGOTIATION AND PARALLEL DETECTION

The Ethernet PHY supports twisted pair auto-negotiation as defined by IEEE 802.3-2008 Clause 28 and IEEE 802.3az.

The auto-negotiation process evaluates the advertised capabilities of the local PHY and its link partner to determine the

best possible operating mode. In particular, auto-negotiation can determine speed, duplex configuration, and master or

slave operating modes for 1000BASE-T. Also, auto-negotiation allows the internal MAC to communicate with its link

partner MAC through the Ethernet PHY using optional “next pages,” which set attributes that may not otherwise be

defined by the IEEE standard.

If the Category 5 link partner does not support auto-negotiation, the Ethernet PHY automatically uses parallel detection

to select the appropriate link speed.

Auto-negotiation is disabled by clearing the Auto-Negotiation Enable bit of the Ethernet PHY Mode Control Register. If

auto-negotiation is disabled, the state of the Ethernet PHY Mode Control Register bits Speed Select[0], Speed Select[1],

and Duplex Mode determine the device operating speed and duplex mode. While 10BASE-T and 100BASE-T do not

require auto-negotiation, clause 40 has defined 1000BASE-T to require auto-negotiation.

9.1.3 1000BASE-T FORCED MODE SUPPORT

The device provide support for a 1000BASE-T forced test mode. In this mode, the Ethernet PHY can be forced into

1000BASE-T mode and does not require manual setting of master/slave at the two ends of the link. This mode is for

test purposes only, and should not be used in normal operation. To configure a PHY in this mode, set the Enable

1000BASE-T Force Mode bit of the Ethernet PHY Page 2 EEE Control Register to 1b, and the Ethernet PHY Mode Con-

trol Register bits Speed Select[1] and Speed Select[0] to 10b.

9.1.4 AUTOMATIC CROSSOVER AND POLARITY DETECTION

For trouble-free configuration and management of Ethernet links, the Ethernet PHY includes a robust automatic cross-

over detection feature for all three speeds on the twisted-pair interface (10BASE-T, 100BASE-T, and 1000BASE-T).

Known as HP Auto-MDIX, the function is fully compliant with clause 40 of the IEEE standard 802.3-2008.

LAN7850

DS00001993D-page 92  2015 - 2017 Microchip Technology Inc.

Additionally, the device detects and corrects polarity errors on all MDI pairs, a useful capability that exceeds the require-

ments of the standard.

Both HP Auto-MDIX detection and polarity correction are enabled in the device by default. The default settings can be

changed via the Disable Auto-MDI/MDI-X Correction and Disable Polarity Inversion Correction bits of the Ethernet PHY

Bypass Control Register. The status bits for each of these functions are located in the Ethernet PHY Auxiliary Control

and Status Register.

The HP Auto-MDIX algorithm successfully detects, corrects, and operates with any of the MDI wiring pair combinations

listed in Table 9-1.

9.1.5 MANUAL MDI/MDI-X SETTING

As an alternative to HP Auto-MDIX detection, the PHY can be forced to be MDI or MDI-X using the MDI/MDI-X Force

Enable bits of the Ethernet PHY Page 1 LED and Crossover Control Register. Setting these bits to 10b forces MDI and

setting to 11b forces MDI-X. Leaving the bits 00b enables the MDI/MDI-X setting to be based on the Disable Auto-MDI/

MDI-X in Forced 10/100 Mode and Disable Auto-MDI/MDI-X Correction bits of the Ethernet PHY Bypass Control Reg-

ister.

9.1.6 LINK SPEED DOWNSHIFT

For operation in cabling environments that are incompatible with 1000BASE-T, the Ethernet PHY provides an automatic

link speed “downshift” option. When enabled, the device automatically changes its 1000BASE-T auto-negotiation adver-

tisement to the next slower speed after a set number of failed attempts at 1000BASE-T. No reset is required to get out

of this state if a subsequent link partner with 1000BASE-T support is connected.

This is useful in setting up in networks using older cable installations that may include only pairs A and B and not pairs

C and D. The two-pair Cable Detection and Auto Downshift Operation enables link-up at 10/100BASE-T speeds in this

scenario.

To configure and monitor link speed downshifting, set the Enable Cable Impairment Auto-Downshift, Link Speed Auto-

Downshift Control, and Apply Downshift bits of the Ethernet PHY Page 1 Extended PHY Control 3 Register.

9.1.7 ENERGY EFFICIENT ETHERNET

The Ethernet PHY supports the IEEE 802.3az Energy Efficient Ethernet standard. This standard provides a method for

reducing power consumption on an Ethernet link during times of low utilization. It uses Low Power Idles (LPI) to achieve

this objective.

Using LPI, the usage model for the link is to transmit data as fast as possible and then return to a low power idle state.

Energy is saved on the link by cycling between active and low power idle states. During LPI, power is reduced by turning

off unused circuits and using this method, energy use scales with bandwidth utilization.

The Ethernet PHY uses LPI to optimize power dissipation in 100BASE-TX and 1000BASE-T modes of operation. In

addition, the IEEE 802.3az standard defines a 10BASE-Te mode that reduces transmit signal amplitude from 5Vpeak-

to-peak to approximately 3.3Vpeak-to-peak. This mode reduces power consumption in 10Mb/s link speed and can fully

inter-operate with legacy 10BASE-T compliant PHYs over 100m Category 5 cable or better.

To configure the Ethernet PHY in 10BASE-Te mode, set the Enable Energy Efficient (802.3az) 10BASE-Te Operating

Mode bit in the Ethernet PHY Page 2 EEE Control Register to 1b. Additional Energy Efficient Ethernet features are con-

trolled through the MMD control and status registers EEE Advertisement (EEE_ADVERTISEMENT) and EEE Link Part-

ner Advertisement (EEE_LP_ADVERTISEMENT).

TABLE 9-1: SUPPORTED MDI PAIR COMBINATIONS

RJ-45 Pin Pairings Mode

1,2 3,6 4,5 7,8

A B C D Normal MDI

B A D C Normal MDI-X

A B D C Normal MDI with pair swap on C and D pair

B A C D Normal MDI-X with pair swap on C and D pair

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 93

LAN7850

9.1.8 CABLE DIAGNOSTICS

The device includes a comprehensive suite of cable diagnostic functions that are available via the Ethernet PHY Page

1 Cable Diagnostics Control 1 Register, Ethernet PHY Page 1 Cable Diagnostics Control 2 Register, and Ethernet PHY

Page 1 Cable Diagnostics Control 3 Register. These functions enable a variety of cable operating conditions and status

to be accessed and checked. When triggered via the Cable Diagnostics Trigger bit in the Ethernet PHY Page 1 Cable

Diagnostics Control 1 Register, the cable diagnostic functions provide the ability to identify the cable length and oper-

ating conditions, and to isolate a variety of common faults that can occur on the Category 5 twisted pair cabling.

The following diagnostic functions are part of the cable diagnostic suite:

• Detecting Coupling Between Cable Pairs

• Detecting Cable Pair Termination

• Determining Cable Length

9.1.8.1 Coupling Between Cable Pairs

Shorted wires, improper termination, or high cross-talk resulting from an incorrect wire map can cause error conditions,

such as anomalous coupling between cable pairs. These conditions can prevent the device from establishing a link at

any speed.

9.1.8.2 Cable Pair Termination

Proper termination of a category 5 cable requires a 100 ohm differential impedance between the positive and negative

cable terminals. IEEE 802.3 allows for a termination of 115 ohms maximum and 85 ohms minimum. If the termination

falls outside of this range, it is reported by the cable diagnostics as an anomalous termination. The diagnostics can also

determine the presence of an open or shorted cable pair.

9.1.8.3 Cable Length

When the category 5 cable in an installation is properly terminated, the cable diagnostics report the approximate cable

length in meters. If there is a cable fault, the distance to the fault is reported. Cable length is reliable to the 120 meter

range.

9.2 Ethernet PHY Power Management

9.2.1 PHY POWER DOWN

The Ethernet PHY can be powered down via the IEEE-specified Power Down bit in the Ethernet PHY Mode Control

9.2.2 ENHANCED PHY POWER MANAGEMENT

In addition to the IEEE-specified power-down control bit, the device also includes an enhanced PHY power manage-

ment mode. This mode enables support for power-sensitive applications. It utilizes a signal-detect function that monitors

the media interface for the presence of a link to determine when to automatically power-down the PHY. The PHY “wakes

up” at a programmable interval and attempts to “wake-up” the link partner PHY by sending a burst of FLP over copper

media.

The enhanced PHY power management mode is enabled during normal operation at any time by setting the Enhanced

PHY Enable bit of the Ethernet PHY Auxiliary Control and Status Register to 1b.

The enhanced PHY power management mode helps conserve power in the following cases:

• An unplugged PHY port

• A PHY port, plugged into a cable with no link partner on the other end

• A PHY port, plugged into a cable with a link partner PHY not transmitting link pulses because it is un-powered, in

reset, or other reasons that prevent it from linking.

Note: When a link is established on the twisted pair interface in the 1000BASE-T mode, cable diagnostics can

be run without disrupting the link or disrupting any data transfer. However, when a link is established in

100BASE-TX or 10BASE-T modes, cable diagnostics cause the link to drop while the diagnostics are run-

ning. After the cable diagnostics are finished, the link is re-established.

LAN7850

DS00001993D-page 94  2015 - 2017 Microchip Technology Inc.

The enhanced PHY power management mode can be used in conjunction with all suspend states with the exception of

SUSPEND2, since the PHY is disabled. Moreover, Enhanced PHY mode can be enabled while in Normal-Configured,

NetDetach and PME mode by setting the Enhanced PHY Enable bit of the Ethernet PHY Auxiliary Control and Status

For PME mode, EEPROM/OTP settings are available to enable the Enhanced PHY mode to be enabled by default.

9.3 LED Interface

The Ethernet PHY provides four LED pins, LED[0:3]. Each LED can be configured to display different status information

that can be selected by setting the corresponding LED Configuration field of the Ethernet PHY LED Mode Select Reg-

ister. The modes in Table 9-2 are equivalent to the settings used in the Ethernet PHY LED Mode Select Register to con-

figure each LED pin. The default LED state is active low and can be changed by modifying the Invert LED Polarity field

of the Ethernet PHY Page 2 EEE Control Register. The blink/pulse-stretch and other LED settings can be configured

via the Ethernet PHY LED Behavior Register. The LED pins can also be configured via EEPROM or OTP (LED Config-

uration 0, LED Configuration 1, LED Configuration 2, LED Configuration 3, LED Configuration 4).

TABLE 9-2: LED MODE AND FUNCTION SUMMARY

Mode Name Description

0 Link/Activity 1 = No link in any speed on any media interface.

0 = Valid link at any speed on any media interface.

Blink or pulse stretch = Valid link at any speed on any media interface

with activity present.

1 Link1000/Activity 1 = No link at 1000BASE-T.

0 = Valid link at 1000BASE-T.

Blink or pulse stretch = Valid link at 1000BASE-T with activity present.

2 Link100/Activity 1 = No link at 100BASE-TX.

0 = Valid link at 100BASE-TX.

Blink or pulse stretch = Valid link at 100BASE-TX with activity present.

3 Link10/Activity 1 = No link at 10BASE-T.

0 = Valid link at 10BASE-T.

Blink or pulse stretch = Valid link at 10BASE-T with activity present.

4 Link100/1000/Activity 1 = No link at 100BASE-TX or 1000BASE-T.

0 = Valid link at 100BASE-TX or 1000BASE-T.

Blink or pulse stretch = Valid link at 100BASE-TX or 1000BASE-T, with

activity present.

5 Link10/1000/Activity 1 = No link at 10BASE-T or 1000BASE-T.

0 = Valid link at 10BASE-T or 1000BASE-T.

Blink or pulse stretch = Valid link at 10BASE-T or 1000BASE-T, with

activity present.

6 Link10/100/Activity 1 = No link at 10BASE-T or 100BASE-TX.

0 = Valid link at 10BASE-T or 100BASE-TX.

Blink or pulse stretch = Valid link at 10BASE-T or 100BASE-TX, with

activity present.

7 RESERVED RESERVED

8 Duplex/Collision 1 = Link established in half-duplex mode, or no link established.

0 = Link established in full-duplex mode.

Blink or pulse stretch = Link established in half-duplex mode but colli-

sions are present.

9 Collision 1 = No collisions detected.

Blink or pulse stretch = Collision detected.

10 Activity 1 = No activity present.

Blink or pulse stretch = Activity present. (becomes TX activity present if

the LED Activity Output Select bit in the Ethernet PHY LED Behavior Reg-

ister is set to 1.)

11 RESERVED RESERVED

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 95

LAN7850

9.3.1 LED BEHAVIOR

Using the Ethernet PHY LED Behavior Register, the following LED behaviors can be configured.

9.3.1.1 LED Combine

Enables an LED to display the status for a combination of primary and secondary modes. This can be enabled or dis-

abled for each LED pin via the LED Combination Disables field of the Ethernet PHY LED Behavior Register. For exam-

ple, a copper link running in 1000BASE-T mode with activity present can be displayed with one LED by configuring an

LED pin to Link1000/Activity mode. The LED asserts when linked to a 1000BASE-T partner and also blinks or performs

pulse-stretch when activity is either transmitted by the PHY or received by the Link Partner. When disabled, the combine

feature only provides status of the selected primary function. In this example, only Link1000 asserts the LED, and the

secondary mode, activity, does not display if the combine feature is disabled.

9.3.1.2 LED Blink or Pulse-Stretch

This behavior is used for activity and collision indication. This can be uniquely configured for each LED pin via the LED

Pulse Stretch Enables field of the Ethernet PHY LED Behavior Register. Activity and collision events can occur randomly

and intermittently throughout the link-up period. Blink is a 50% duty cycle oscillation of asserting and de-asserting an

LED pin. Pulse-stretch guarantees that an LED is asserted and de-asserted for a specific period of time when activity

is either present or not present. These rates can also be configured, as detailed in Section 9.3.1.3, "Rate of LED Blink

or Pulse-Stretch".

9.3.1.3 Rate of LED Blink or Pulse-Stretch

This behavior controls the LED blink rate or pulse-stretch length when the blink/pulse-stretch is enabled (LED Pulse

Stretch Enables) on an LED pin. This can be uniquely configured for each LED pin via the LED Blink / Pulse-Stretch

Rate field of the Ethernet PHY LED Behavior Register. The blink rate, which alternates between a high and low voltage

level at a 50% duty cycle, can be set to 2.5 Hz, 5 Hz, 10 Hz, or 20 Hz. For pulse-stretch, the rate can be set to 50 ms,

100 ms, 200 ms, or 400 ms.

9.3.1.4 LED Pulsing Enable

To provide additional power savings, the LEDs (when asserted) can be pulsed at 5 kHz, 20% duty cycle, by setting the

LED Pulsing Enable bit of the Ethernet PHY LED Behavior Register.

12 Auto-negotiation Fault 1 = No auto-negotiation fault present.

0 = Auto-negotiation fault occurred.

13 RESERVED RESERVED

14 Force LED Off 1 = De-asserts the LED.

15 Force LED On 0 = Asserts the LED.

TABLE 9-2: LED MODE AND FUNCTION SUMMARY (CONTINUED)

Mode Name Description

LAN7850

DS00001993D-page 96  2015 - 2017 Microchip Technology Inc.

9.4 Test Features

The Ethernet PHY includes several testing features designed to facilitate system-level debugging and production test-

ing. These are detailed in the following sub-sections.

9.4.1 ETHERNET PACKET GENERATOR

The Ethernet Packet Generator (EPG) can be used at each of the 10/100/1000BASE-T speed settings for Copper Cat-

egory 5 media to isolate problems between the MAC and PHY, or between a locally connected PHY and its remote link

partner. Enabling the EPG feature effectively disables all MAC interface transmit pins and selects the EPG as the source

for all data transmitted onto the twisted pair interface.

To enable the EPG feature, set the EPG Enable bit to 1b in the Ethernet PHY Page 1 Ethernet Packet Generator (EPG)

Control 1 Register. When the EPG is enabled, packet loss occurs during transmission of packets from the MAC to the

PHY. However, the PHY receive output pins to the MAC are still active when the EPG is enabled.

When the EPG Run/Stop bit of the Ethernet PHY Page 1 Ethernet Packet Generator (EPG) Control 1 Register is set to

1b, the PHY begins transmitting Ethernet packets based on the settings in the Ethernet PHY Page 1 Ethernet Packet

Generator (EPG) Control 1 Register and Ethernet PHY Page 1 Ethernet Packet Generator (EPG) Control 2 Register.

These registers set:

• Source and destination addresses for each packet

• Packet size

• Inter-packet gap

• FCS state

• Transmit duration

• Payload pattern

If the Transmission Duration bit of the Ethernet PHY Page 1 Ethernet Packet Generator (EPG) Control 1 Register is set

to 0, the EPG Run/Stop bit is cleared automatically after 30,000,000 packets are transmitted.

9.4.2 CRC COUNTERS

A set of Cyclical Redundancy Checking (CRC) counters are available to monitor traffic on the copper interface. Two

separate CRC counters are available:

• Good packet Counter (Packet Counter field in the Ethernet PHY Page 1 Receive Good Counter Register)

• Bad Packet Counter (Receive Packet CRC Error Counter field in the Ethernet PHY Page 1 Extended PHY Control

4 Register)

The good CRC counters highest value is 9,999 packets. After this value is reached, the counter clears on the 10,000th

packet and continues to count additional packets beyond that value. The bad CRC counter stops counting when it

reaches its maximum counter limit of 255 packets.

The device CRC counters operate in the 10/100/1000BASE-T mode as follows:

• After receiving a packet on the media interface, the Packet Counter Active bit of the Ethernet PHY Page 1 Receive

Good Counter Register is set and cleared after being read.

• The packet then is counted by either the good CRC counter (Packet Counter field in the Ethernet PHY Page 1

Receive Good Counter Register) or the bad CRC counter (Receive Packet CRC Error Counter field in the Ether-

net PHY Page 1 Extended PHY Control 4 Register).

• Both CRC counters are also automatically cleared when read.

Note: The EPG is intended for use with laboratory or in-system testing equipment only. Do not use the EPG test-

ing feature when the device is connected to a live network.

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 97

LAN7850

9.4.3 FAR-END LOOPBACK

The far-end loopback testing feature is enabled by setting the Far-End Loopback Enable bit of the Ethernet PHY

Extended PHY Control 1 Register to 1b. When enabled, it forces incoming data from a link partner on the current media

interface, into the MAC interface of the PHY, to be retransmitted back to the link partner on the media interface as shown

in Figure 9-1. In addition, the incoming data also appears on the receive data pins of the MAC interface. Data present

on the transmit data pins of the MAC interface is ignored when using this testing feature.

9.4.4 NEAR-END LOOPBACK

When the near-end loopback testing feature is enabled (by setting the Digital Loopback bit of the Ethernet PHY Mode

Control Register to 1b), data on the transmit data pins (TXD) is looped back in the PCS block, onto the device receive

data pins (RXD), as shown in Figure 9-2. When using this testing feature, no data is transmitted over the network.

9.4.5 CONNECTOR LOOPBACK

The connector loopback testing feature allows the twisted pair interface to be looped back externally. When using this

feature, the PHY must be connected to a loopback connector or a loopback cable. Pair A should be connected to pair

B, and pair C to pair D, as shown in Figure 9-3. The connector loopback feature functions at all available interface

speeds.

When using the connector loopback testing feature, the device auto-negotiation, speed, and duplex configuration is set

using the Ethernet PHY Mode Control Register, Ethernet PHY Device Auto-Negotiation Advertisement Register, and

Ethernet PHY 1000BASE-T Control Register. For 1000BASE-T connector loopback, the following additional writes are

required to be executed in the following order:

1. Enable the 1000BASE-T connector loopback. Set the Cable Loopback Mode Enable bit of the Ethernet PHY

Extended PHY Control 2 Register to 1b.

2. Disable pair swap correction. Set the Disable Auto-MDI/MDI-X Correction bit of the Ethernet PHY Bypass Control

FIGURE 9-1: FAR-END LOOPBACK DIAGRAM

FIGURE 9-2: NEAR-END LOOPBACK DIAGRAM

LAN7850

DS00001993D-page 98  2015 - 2017 Microchip Technology Inc.

FIGURE 9-3: CONNECTOR LOOPBACK DIAGRAM

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 99

LAN7850

10.0 EEPROM CONTROLLER (EEP)

The device may use an external EEPROM to store the default values for the USB descriptors and the MAC address.

The EEPROM controller supports most “93C56 or 93C66” type 256/512 byte EEPROMs. A total of nine address bits are

used.

After a system-level reset occurs, the device will load the default values from EEPROM. The device will not accept USB

transactions from the Host until this process is completed.

The EEPROM controller also allows the Host to read, write and erase the contents of the Serial EEPROM.

10.1 EEPROM and OTP Relationship

A detected external EEPROM shall always take precedence over OTP. When determining the source to configure the

device, the following order is used:

1. EEPROM Configuration

2. OTP Configuration

3. CSR defaults

The CSR defaults are used if the OTP is determined to be unconfigured.

10.2 EEPROM Auto-Load

Certain system level resets (USB Reset, Power-On Reset (POR), External Chip Reset (RESET_N), and Soft Reset

(SRST)) cause the EEPROM contents to be loaded into the device. After a reset, the EEPROM controller attempts to

read the first byte of data from the EEPROM. If the value A5h is read from the first address, then the EEPROM controller

will assume that a programmed external Serial EEPROM is present.

The EEPROM Controller will then load contents of the EEPROM into an internal 512 byte Descriptor SRAM. The con-

tents of the RAM are accessed by the USB EP0 Control Block as needed (i.e., to fill Get Descriptor commands). A

detailed explanation of the EEPROM byte ordering with respect to the MAC address is given in Section 15.1.45, "MAC

Receive Address Low Register (RX_ADDRL)," on page 191.

If A5h is not read from the first address, the EEPROM controller will end initialization. The default values, as specified

in the associated registers and USB descriptors, shall be assumed unless a configured OTP is present.

Where there is no EEPROM or OTP it is the responsibility of the Host LAN driver software to set the IEEE 802.3 address

by writing to the MAC Receive Address High Register (RX_ADDRH) and MAC Receive Address Low Register (RX_AD-

DRL).

The device will not respond to the USB Host until the EEPROM loading sequence has completed. Therefore, after reset,

the USB PHY is kept in the disconnect state until the EEPROM load has completed.

10.3 EEPROM Host Operations

After the EEPROM controller has finished reading (or attempting to read) the EEPROM after a system-level reset, the

Host is free to perform other EEPROM operations. EEPROM operations are performed using the EEPROM Command

(E2P_CMD) and EEPROM Data (E2P_DATA) registers. Section 15.1.12, "EEPROM Command Register (E2P_CMD),"

on page 160 provides an explanation of the supported EEPROM operations.

If the EEPROM operation is the “write location” (WRITE) or “write all” (WRAL) commands, the Host must first write the

desired data into the E2P_DATA register. The Host must then issue the WRITE or WRAL command using the E2P_CMD

must also be set to the desired location. The command is executed when the Host sets the EPC_BSY bit high. The

completion of the operation is indicated when the EPC_BSY bit is cleared.

Note: A 3-wire style 2K/4K EEPROM that is organized for 256/512 x 8-bit operation must be used.

Note: The USB reset only loads the MAC address.

LAN7850

DS00001993D-page 100  2015 - 2017 Microchip Technology Inc.

If the EEPROM operation is the “read location” (READ) operation, the Host must issue the READ command using the

E2P_CMD register with the EPC_ADDR set to the desired location. The command is executed when the Host sets the

EPC_BSY bit high. The completion of the operation is indicated when the EPC_BSY bit is cleared, at which time the

data from the EEPROM may be read from the E2P_DATA register.

Other EEPROM operations are performed by writing the appropriate command to the E2P_CMD register. The command

is executed when the Host sets the EPC_BSY bit high. The completion of the operation is indicated when the EPC_BSY

bit is cleared. In all cases, the Host must wait for EPC_BSY to clear before modifying the E2P_CMD register.

If an operation is attempted, and an EEPROM device does not respond within 30 ms, the device will timeout, and the

EPC Time-out bit (EPC_TO) in the E2P_CMD register will be set.

Figure 10-1 illustrates the Host accesses required to perform an EEPROM Read or Write operation.

Note: The EEPROM device powers-up in the erase/write disabled state. To modify the contents of the EEPROM,

the Host must first issue the EWEN command.

FIGURE 10-1: EEPROM ACCESS FLOW DIAGRAM

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 101

LAN7850

10.3.1 SUPPORTED EEPROM OPERATIONS

The EEPROM controller supports the following EEPROM operations under Host control via the E2P_CMD register. The

operations are commonly supported by “93C46” EEPROM devices. A description and functional timing diagram is pro-

vided below for each operation. Please refer to the E2P_CMD register description in Section 15.1.12, "EEPROM Com-

mand Register (E2P_CMD)," on page 160 for E2P_CMD field settings for each command.

ERASE (Erase Location): If erase/write operations are enabled in the EEPROM, this command will erase the location

selected by the EPC Address field (EPC_ADDR). The EPC_TO bit is set if the EEPROM does not respond within 30 ms.

ERAL (Erase All): If erase/write operations are enabled in the EEPROM, this command will initiate a bulk erase of the

entire EEPROM.The EPC_TO bit is set if the EEPROM does not respond within 30 ms.

FIGURE 10-2: EEPROM ERASE CYCLE

FIGURE 10-3: EEPROM ERAL CYCLE

LAN7850

DS00001993D-page 102  2015 - 2017 Microchip Technology Inc.

EWDS (Erase/Write Disable): After issued, the EEPROM will ignore erase and write commands. To re-enable erase/

write operations issue the EWEN command.

EWEN (Erase/Write Enable): Enables the EEPROM for erase and write operations. The EEPROM will allow erase and

write operations until the “Erase/Write Disable” command is sent, or until power is cycled.

The EEPROM device will power-up in the erase/write-disabled state. Any erase or write operations will fail until an

Erase/Write Enable command is issued.

FIGURE 10-4: EEPROM EWDS CYCLE

FIGURE 10-5: EEPROM EWEN CYCLE

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 103

LAN7850

READ (Read Location): This command will cause a read of the EEPROM location pointed to by EPC Address

(EPC_ADDR). The result of the read is available in the E2P_DATA register.

WRITE (Write Location): If erase/write operations are enabled in the EEPROM, this command will cause the contents

of the E2P_DATA register to be written to the EEPROM location selected by the EPC Address field (EPC_ADDR). The

EPC_TO bit is set if the EEPROM does not respond within 30 ms.

FIGURE 10-6: EEPROM READ CYCLE

FIGURE 10-7: EEPROM WRITE CYCLE

LAN7850

DS00001993D-page 104  2015 - 2017 Microchip Technology Inc.

WRAL (Write All): If erase/write operations are enabled in the EEPROM, this command will cause the contents of the

E2P_DATA register to be written to every EEPROM memory location. The EPC_TO bit is set if the EEPROM does not

respond within 30 ms.

Table 10-1 details the number of EECLK cycles required for each EEPROM operation.

10.3.2 HOST INITIATED EEPROM RELOAD

The Host can initiate a reload of the EEPROM by issuing the RELOAD command via the EEPROM Command Register

(E2P_CMD). If the first byte read from the EEPROM is not 0xA5, it is assumed that the EEPROM is not present, or not

programmed, and the reload will fail. The Data Loaded bit of the EEPROM Command Register (E2P_CMD) indicates a

successful reload of the EEPROM.

10.3.3 EEPROM COMMAND AND DATA REGISTERS

Refer to Section 15.1.12, "EEPROM Command Register (E2P_CMD)," on page 160 and Section 15.1.13, "EEPROM

Data Register (E2P_DATA)," on page 162 for a detailed description of these registers. Supported EEPROM operations

are described in these sections.

10.3.4 EEPROM TIMING

Refer to Section 16.6.4, "EEPROM Timing," on page 268 for detailed EEPROM timing specifications.

FIGURE 10-8: EEPROM WRAL CYCLE

TABLE 10-1: REQUIRED EECLK CYCLES

Operation Required EECLK Cycles

ERASE 10

ERAL 10

EWDS 10

EWEN 10

WRITE 18

WRAL 18

Note: It is not recommended that the RELOAD command be used as part of normal operation, as race conditions

can occur with USB Commands that access descriptor data. It is recommended that the Host driver issue

a Soft Reset (SRST) to reload the EEPROM data.

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 105

LAN7850

10.4 EEPROM Format

Table 10-2 illustrates the format in which data is stored inside of the EEPROM.

The EEPROM offsets are given in units of 16-bit word offsets. A length field with a value of zero indicates that the field

does not exist in the EEPROM. The device will use the field’s hardware default value in this case.

Note: For the device descriptor the only valid values for the length are 0 and 18.

For the configuration and interface descriptor the only valid values for the length are 0 and 18.

For the Binary Object Store (BOS) Block, the length varies and is dependent on block components.

The EEPROM programmer must ensure that if a string descriptor does not exist in the EEPROM, the ref-

erencing descriptor must contain 00h for the respective string index field.

If all string descriptor lengths are zero, then a Language ID will not be supported.

All reserved EEPROM bits must be set to 0.

TABLE 10-2: EEPROM FORMAT

EEPROM offset EEPROM Contents

00h 0xA5 (EEPROM Programmed Indicator)

01h MAC Address [7:0]

02h MAC Address [15:8]

03h MAC Address [23:16]

04h MAC Address [31:24]

05h MAC Address [39:32]

06h MAC Address [47:40]

07h GPIO[7:0] Wakeup Enables

Used to load LSB of the GPIO Wake 0-11 (GPIOWK[11:0]) field of the General Purpose IO

Wake Enable and Polarity Register (GPIO_WAKE)

08h GPIO[11:8] Wakeup Enables

Used to load bits 11:8 of the GPIO Wake 0-11 (GPIOWK[11:0]) field of the General Pur-

pose IO Wake Enable and Polarity Register (GPIO_WAKE)

09h GPIO PME Flags 0

0Ah GPIO PME Flags 1

0Bh LED Configuration 0

0Ch LED Configuration 1

0Dh LED Configuration 2

0Eh GPIO[7:0] Wakeup Polarity

Used to load LSB of the GPIO Polarity 0-11 (GPIOPOL[11:0]) field of General Purpose IO

Wake Enable and Polarity Register (GPIO_WAKE)

LAN7850

DS00001993D-page 106  2015 - 2017 Microchip Technology Inc.

0Fh GPIO[11:8] Wakeup Polarity

Used to load bits 11:8 of the GPIO Polarity 0-11 (GPIOPOL[11:0]) field of General Purpose

IO Wake Enable and Polarity Register (GPIO_WAKE)

10h Full-Speed Polling Interval for Interrupt Endpoint

11h High-Speed Polling Interval for Interrupt Endpoint

12h RESERVED (write as 0)

13h Configuration Flags 0 [7:0]

14h Configuration Flags 0 [15:8]

15h Configuration Flags 0 [23:16]

16h Configuration Flags 0 [31:24]

17h Configuration Flags 1 [7:0]

18h Configuration Flags 1 [15:8]

19h Configuration Flags 1 [23:16]

1Ah Configuration Flags 1 [31:24]

1Bh Configuration Flags 2 [7:0]

1Ch Configuration Flags 2 [15:8]

1Dh Configuration Flags 2 [23:16]

1EH Configuration Flags 2 [31:24]

1Fh Configuration Flags 3 [7:0]

20h Configuration Flags 3 [15:8]

21h Configuration Flags 3 [23:16]

22h Configuration Flags 3 [31:24]

23h Language ID [7:0]

24h Language ID [15:8]

25h Manufacturer ID String Descriptor Length (bytes)

26h Manufacturer ID String Descriptor EEPROM Word Offset

27h Product Name String Descriptor Length (bytes)

28h Product Name String Descriptor EEPROM Word Offset

29h Serial Number String Descriptor Length (bytes)

2Ah Serial Number String Descriptor EEPROM Word Offset

2Bh Configuration String Descriptor Length (bytes)

2Ch Configuration String Descriptor Word Offset

2Dh Interface String Descriptor Length (bytes)

TABLE 10-2: EEPROM FORMAT (CONTINUED)

EEPROM offset EEPROM Contents

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 107

LAN7850

Note 10-1 This block may include Binary Object Store (BOS) Descriptor, USB 2.0 Extension Descriptor, and

Container ID Descriptor.

Note 10-2 The length shall always be 20 bytes when this feature is used.

Note 10-3 The first four bytes specified at this address contains the WUF configuration data. The next

subsequent 16 bytes are allocated to the mask. This data is used to set filter 0 in Wakeup Filter x

Configuration Register (WUF_CFGx) and Wakeup Filter x Byte Mask Registers (WUF_MASKx).

Note 10-4 The length shall always be 4 bytes when this feature is used.

2Eh Interface String Descriptor Word Offset

2Fh Binary Object Store (BOS) Block Length (Bytes) (See Note 10-1)

30h Binary Object Store (BOS) Block Word Offset (See Note 10-1)

31h - 34h RESERVED (Must be written as 0000_0000h)

35h High-Speed Device Descriptor Length (bytes)

36h High-Speed Device Descriptor Word Offset

37h High-Speed Configuration and Interface Descriptor Length (bytes)

38h High-Speed Configuration and Interface Descriptor Word Offset

39h Full-Speed Device Descriptor Length (bytes)

3Ah Full-Speed Device Descriptor Word Offset

3Bh Full-Speed Configuration and Interface Descriptor Length (bytes)

3Ch Full-Speed Configuration and Interface Descriptor Word Offset

3Dh Wake Frame Filter 0 Configuration and Mask Length (bytes) (See Note 10-2)

3Eh Wake Frame Filter 0 Configuration and Mask Word Offset (See Note 10-3)

3Fh - 40h RESERVED (Must be written as 0000h)

41h Common Test Bus In Length (bytes) (See Note 10-4)

42h Common Test Bus In Word Offset (bytes)

43h - 44h RESERVED (Must be written as 0200h)

45h RESERVED (Must be written as 00h)

46h SW Descriptor Length (bytes)

47h SW Descriptor Word Offset (bytes)

48h - 4Fh GPIO Configuration

50h - 57h RESERVED (Must be written as 00h)

58h LED Configuration 3

59h LED Configuration 4

5Ah - 61h RESERVED (Must be written as TBD)

TABLE 10-2: EEPROM FORMAT (CONTINUED)

EEPROM offset EEPROM Contents

LAN7850

DS00001993D-page 108  2015 - 2017 Microchip Technology Inc.

10.4.1 GPIO PME FLAGS 0

Table 10-3 describes the GPIO PME Flags 0 byte.

TABLE 10-3: GPIO PME FLAGS 0

BIT DESCRIPTION

7GPIO PME Enable

Setting this bit enables the assertion of the PME_N pin, as a result of a Wakeup (GPIO) pin, Packet,

WUFF, Perfect DA or PHY Link Change.

0 = The device does not support GPIO PME signaling.

1 = The device supports GPIO PME signaling.

Note: When this bit is 0, the remaining GPIO PME parameters in this flag byte are ignored.

6GPIO PME Configuration

This bit selects whether the GPIO PME is a level or a pulse on the PME_N pin. If pulse is selected,

the duration of the pulse is determined by the setting of the GPIO PME Length bit of this flag byte. The

level of the signal or the polarity of the pulse is determined by the GPIO PME Polarity bit of this flag

byte.

0 = GPIO PME is signaled via a level.

1 = GPIO PME is signaled via a pulse.

Note: If GPIO PME Enable is 0, this bit is ignored.

5GPIO PME Length

When the GPIO PME Configuration bit of this flag byte indicates that the GPIO PME is signaled by a

pulse on the PME_N pin, this bit determines the duration of the pulse.

0 = GPIO PME pulse length is 1.5 ms.

1 = GPIO PME pulse length is 150 ms.

Note: If GPIO PME Enable is 0, this bit is ignored.

Note: The pulse length is relative to the first wakeup event received by the device. In the event that

additional wake events are received during the duration of the PME pulse the assertion length

shall not be affected.

4GPIO PME Polarity

Specifies the level of the signal or the polarity of the pulse used for GPIO PME signaling.

0 = GPIO PME signaling polarity is low.

1 = GPIO PME signaling polarity is high.

Note: If GPIO PME Enable is 0, this bit is ignored.

3GPIO PME Buffer Type

This bit selects the output buffer type for the PME_N pin.

0 = Open drain driver

1 = Push-Pull driver

Note: If GPIO PME Enable is 0, this bit is ignored.

2PHY Link Change Enable

This bit selects whether PHY Link Change wakeup event is supported.

0 = PHY link change wakeup not supported

1 = PHY link change wakeup supported

Note: If GPIO PME Enable is 0, this bit is ignored.

1PME Packet Enable

This bit enables/disables Packet detection and wakeup.

0 = Packet event wakeup disabled.

1 = Packet event wakeup enabled.

Note: If GPIO PME Enable is 0, this bit is ignored.

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 109

LAN7850

10.4.2 GPIO PME FLAGS 1

Table 10-4 describes the GPIO PME Flags 1 byte.

0PME Perfect DA Enable

This bit enables/disables Perfect DA detection and wakeup.

0 = Perfect DA event wakeup disabled.

1 = Perfect DA event wakeup enabled.

Note: If GPIO PME Enable is 0, this bit is ignored.

Note: The contents of this field defines several defaults for the Flag Attributes Register (FLAG_ATTR).

TABLE 10-4: GPIO PME FLAGS 1

BIT DESCRIPTION

7RESERVED

6GPIO CONNECT Buffer Type

This bit selects the output buffer type for the CONNECT pin.

0 = Open drain driver

1 = Push-Pull driver

Note: If GPIO CONNECT Enable is 0, this bit is ignored.

5GPIO CONNECT Enable

Setting this bit enables the assertion of the CONNECT pin, when the USB device controller is ready

to attach to the host.

0 = The device does not support GPIO CONNECT signaling.

1 = The device supports GPIO CONNECT signaling.

4GPIO CONNECT Polarity

Specifies the level of the signal or the polarity of the CONNECT pin.

0 = GPIO CONNECT signaling polarity is low.

1 = GPIO CONNECT signaling polarity is high.

Note: If GPIO CONNECT Enable is 0, this bit is ignored.

3:2 RESERVED

1PME Broadcast Packet Enable

When set this bit enables/disables Broadcast Packet detection and wakeup.

0 = Broadcast Packet event wakeup disabled.

1 = Broadcast Packet event wakeup enabled.

0PME WUFF Enable

When set this bit enables/disables wakeup frame detection and wakeup. When enabled wakeup frame

filter 0 is configured from EEPROM/OTP.

0 = Wakeup Frame detection disabled.

1 = Wakeup Frame detection enabled.

Note: The contents of this field defines several defaults for the Flag Attributes Register (FLAG_ATTR).

TABLE 10-3: GPIO PME FLAGS 0 (CONTINUED)

BIT DESCRIPTION

LAN7850

DS00001993D-page 110  2015 - 2017 Microchip Technology Inc.

10.4.3 LED CONFIGURATION 0

10.4.4 LED CONFIGURATION 1

Note: The CONNECT pin function is only supported when the device is enabled for HSIC operation.

TABLE 10-5: LED CONFIGURATION 0

BIT DESCRIPTION

7:4 RESERVED

3LED3 Enable (LED3_EN)

When set, the LED3 pin is enabled.

2LED2 Enable (LED2_EN)

When set, the LED2 pin is enabled.

1LED1 Enable (LED1_EN)

When set, the LED1 pin is enabled.

0LED0 Enable (LED0_EN)

When set, the LED0 pin is enabled.

Note: The contents of this field defines several defaults for the Hardware Configuration Register (HW_CFG).

TABLE 10-6: LED CONFIGURATION 1

BIT DESCRIPTION

7:4 LED1 Control

This field determines the function displayed on the LED1 pin.

The value specified here is loaded into the LED1 Configuration field of the Ethernet PHY LED Mode

Select Register.

3:0 LED0 Control

This field determines the function displayed on the LED0 pin.

The value specified here is loaded into the LED0 Configuration field of the Ethernet PHY LED Mode

Select Register.

Note: The contents of this field defines several defaults for the Ethernet PHY LED Mode Select Register.

APPLICATION NOTE: In order to implement EEPROM-Less operation, the Ethernet PHY LED Mode Select

Configuration Register (HW_CFG).

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 111

LAN7850

10.4.5 LED CONFIGURATION 2

10.4.6 LED CONFIGURATION 3

TABLE 10-7: LED CONFIGURATION 2

BIT DESCRIPTION

7:4 LED3 Control

This field determines the function displayed on the LED3 pin.

The value specified here is loaded into the LED3 Configuration field of the Ethernet PHY LED Mode

Select Register.

3:0 LED2 Control

This field determines the function displayed on the LED2 pin.

The value specified here is loaded into the LED2 Configuration field of the Ethernet PHY LED Mode

Select Register.

Note: The contents of this field defines several defaults for the Ethernet PHY LED Mode Select Register.

APPLICATION NOTE: In order to implement EEPROM-Less operation, the Ethernet PHY LED Mode Select

Configuration Register (HW_CFG).

TABLE 10-8: LED CONFIGURATION 3

BIT DESCRIPTION

7:0 LED Behavior [7:0]

The value specified here is loaded into bits [7:0] of the Ethernet PHY LED Behavior Register.

Note: The contents of this field defines several defaults for the Ethernet PHY LED Behavior Register.

APPLICATION NOTE: In order to implement EEPROM-Less operation, the Ethernet PHY LED Behavior Register

supports reset protection via Reset Protection (RST_PROTECT) in the Hardware

Configuration Register (HW_CFG).

LAN7850

DS00001993D-page 112  2015 - 2017 Microchip Technology Inc.

10.4.7 LED CONFIGURATION 4

10.4.8 CONFIGURATION FLAGS 0

Table 10-10 describes Configuration Flags 0. If a configuration descriptor exists in the EEPROM, its values must agree

with analogous values contained in the Configuration Flags 0. If they do not, unexpected results and untoward operation

may occur.

TABLE 10-9: LED CONFIGURATION 4

BIT DESCRIPTION

7:0 LED Behavior [15:8]

The value specified here is loaded into bits [15:8] of the Ethernet PHY LED Behavior Register.

Note: The contents of this field defines several defaults for the Ethernet PHY LED Behavior Register.

APPLICATION NOTE: In order to implement EEPROM-Less operation, the Ethernet PHY LED Behavior Register

supports reset protection via Reset Protection (RST_PROTECT) in the Hardware

Configuration Register (HW_CFG).

TABLE 10-10: CONFIGURATION FLAGS 0

BIT DESCRIPTION

31 HSIC 50ohm Driver Data and Strobe Enable (HSIC_DS_EN50)

Refer to the HSIC 50ohm Driver Data and Strobe Enable (HSIC_DS_EN50) field of the HSIC Enable

30 HSIC Slew Tune Test Bit Data and Strobe (HSIC_DS_SLEW_TUNE)

Refer to the HSIC Slew Tune Test Bit Data and Strobe (HSIC_DS_SLEW_TUNE) field of the HSIC

Enable Register (HSIC_EN) for permissible values.

29:27 Squelch Threshold (CFG0_SQU_THR)

Refer to the Squelch Tune (USB2_SQU_TUNE) field of the USB 2.0 AFE Upstream Control Register

(USB2_AFE_CTRL) for permissible values.

26:22 RESERVED

21 HSIC Pin Swap (HSIC_PIN_SWAP)

Refer to the HSIC Pin Swap (HSIC_PIN_SWAP) field of the HSIC Enable Register (HSIC_EN) for

permissible values.

20 Suspend Enable (SUSP_EN)

Refer to the Suspend Enable (SUSP_EN) bit of the USB Configuration Register 0 (USB_CFG0) for

permissible values.

19:18 SUSPEND_N Select (CFG0_SUSPEND_N_SEL)

Refer to the SUSPEND_N Pin Select (SUSPEND_N_SEL) bit of the Hardware Configuration Register

(HW_CFG) for permissible values.

17 SUSPEND_N Polarity (CFG0_SUSPEND_N_POL)

Refer to the SUSPEND_N Pin Polarity (SUSPEND_N _POL) bit of the Hardware Configuration Register

(HW_CFG) for permissible values.

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 113

LAN7850

16 Automatic Duplex Detection (CFG0_ADD)

Refer to the Automatic Duplex Detection (ADD) bit of the MAC Control Register (MAC_CR) for

permissible field values.

15 Automatic Speed Detection (CFG0_ASD)

Refer to the Automatic Speed Detection (ASD) bit of the MAC Control Register (MAC_CR) for

permissible field values.

14:13 Enhanced PHY Sleep Timer (PHY_SLEEP_TIMER)

The field sets the value for the Enhanced PHY Sleep Timer which is controlled by the Enhanced PHY

Sleep Timer field of the Ethernet PHY Page 1 Extended PHY Control 3 Register.

12:11 Enhanced PHY Wake Timer (PHY_WAKE_TIMER)

The field sets the value for the Enhanced PHY Wake Timer which is controlled by the Enhanced PHY

Wake Timer field of the Ethernet PHY Page 1 Extended PHY Control 3 Register.

10:9 Link Time Out Control (LINK_TIME_OUT_CTRL)

The field sets the value for the status timeout control which is controlled by the Link Status Timeout

Control [1] and Link Status Timeout Control [0] fields of the Ethernet PHY Auxiliary Control and Status

8Enhanced PHY Enable (ACT_PHY_EN)

When set, the Enhanced PHY mode is enabled by default. This sets the value of the Enhanced PHY

Enable bit of the Ethernet PHY Auxiliary Control and Status Register.

7Enable Link Power Management Mode (COM_PLL_LPM_MODE)

Refer to the Enable Link Power Management Mode (COM_PLL_LPM_MODE) bit of the Common Block

Test Register (COM_TEST) for permissible values.

6:4 PHY Boost (CFG0_PHY_BOOST)

Refer to the HS Output Current (PHY_BOOST) field of the USB 2.0 AFE Test Register (USB2_TEST)

for permissible values.

3Port Swap (CFG0_PORT_SWAP)

Refer to the Port Swap (PORT_SWAP) bit of the USB Configuration Register 0 (USB_CFG0) for

permissible values.

2LPM Capable (CFG0_LPM_CAPABLE)

Refer to the LPM Capability (LPM_CAP) bit of the USB Configuration Register 0 (USB_CFG0) for

permissible values.

1Remote Wakeup (CFG0_RMT_WKP)

Refer to the Remote Wakeup Support (RMT_WKP) bit of the USB Configuration Register 0

(USB_CFG0) for permissible values.

0Power Method (CFG0_PWR_SEL)

Refer to the Power Method (PWR_SEL) bit of the USB Configuration Register 0 (USB_CFG0) for

permissible values.

Note: Power Method, Remote Wakeup, LPM Enable and other such fields specified in Configuration Flags 0 must

agree with analogous quantities specified in descriptors. If they do not, unexpected results and untoward

operation may occur.

TABLE 10-10: CONFIGURATION FLAGS 0 (CONTINUED)

BIT DESCRIPTION

LAN7850

DS00001993D-page 114  2015 - 2017 Microchip Technology Inc.

10.4.9 CONFIGURATION FLAGS 1

Table 10-11 describes Configuration Flags 1.

TABLE 10-11: CONFIGURATION FLAGS 1

BITS DESCRIPTION

31:17 RESERVED

16 Crystal Suspend Disable (XTAL_SUSP_DIS)

Refer to the Crystal Suspend Disable (XTAL_SUSP_DIS) bit of the Power Management Control

15:7 RESERVED

6TX Swing (TxSwing)

TX Swing (TxSwing) bit of the PIPE Control Register (PIPE_CTL).

Refer to Table 5-3 of the PIPE3 specification for details.

5:3 TX Margin (TxMargin)

TX Margin (TxMargin) bit of the PIPE Control Register (PIPE_CTL).

Refer to table 5-3 of the PIPE3 specification.

2:1 TX Deemphasis (TxDeemphasis)

TX Deemphasis (TxDeemphasis) bit of the PIPE Control Register (PIPE_CTL).

Refer to table 5-3 of the PIPE3 specification.

0Elasticity Buffer Mode (ElasticityBufferMode)

Elasticity Buffer Mode (ElasticityBufferMode) bit of the PIPE Control Register (PIPE_CTL).

Note: Refer to table 5-3 of the PIPE3 specification.

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 115

LAN7850

10.4.10 CONFIGURATION FLAGS 2

Table 10-12 describes Configuration Flags 2.

TABLE 10-12: CONFIGURATION FLAGS 2

BITS DESCRIPTION

31:14 RESERVED

13 Automatic Duplex Polarity (ADP)

See Section 15.1.38, "MAC Control Register (MAC_CR)," on page 184

12 EEE PHY Link Up Speed Up (EEE_PHY_LINK_CHANGE_SPEED_UP)

See Section 15.1.3, "Hardware Configuration Register (HW_CFG)," on page 146

11 Energy Efficient Ethernet TX Clock Stop Enable (EEE_TX_CLK_STOP_EN)

See Section 15.1.38, "MAC Control Register (MAC_CR)," on page 184

10 Energy Efficient Ethernet Enable (EEEEN)

See Section 15.1.38, "MAC Control Register (MAC_CR)," on page 184

9Energy Efficient Ethernet TX LPI Automatic Removal Enable

(EEE_TX_LPI_AUTO_REMOVAL_EN)

See Section 15.1.38, "MAC Control Register (MAC_CR)," on page 184

8Duplex Mode (DPX)

See Section 15.1.38, "MAC Control Register (MAC_CR)," on page 184

7:6 MAC Configuration (CFG)

See Section 15.1.38, "MAC Control Register (MAC_CR)," on page 184

5:3 HS Timeout Calibration (HS_TOutCal)

See Section 15.1.22, "USB Configuration Register 1 (USB_CFG1)," on page 171

2:0 FS Timeout Calibration (FS_TOutCal)

See Section 15.1.22, "USB Configuration Register 1 (USB_CFG1)," on page 171

LAN7850

DS00001993D-page 116  2015 - 2017 Microchip Technology Inc.

10.4.11 CONFIGURATION FLAGS 3

Table 10-13 describes Configuration Flags 3.

10.4.12 GPIO CONFIGURATION

Table 10-13 describes the GPIO configuration field of the EEPROM (Table 10-2). These bits define the defaults for the

respective fields in Section 15.1.5, "General Purpose IO Configuration 0 Register (GPIO_CFG0)" and Section 15.1.6,

"General Purpose IO Configuration 1 Register (GPIO_CFG1)".

10.5 EEPROM Defaults

The signature value of 0xA5 is stored at address 0. A different signature value indicates to the EEPROM controller that

no EEPROM is attached to the device. In this case, and where the OTP is likewise not configured, the defaults values

are specified in the respective CSR loaded from the EEPROM. EEPROM fields not loaded into CSRs (e.g. Vendor ID,

Product ID) have their defaults defined in the respective descriptors in Section 5.7, "USB Descriptors".

TABLE 10-13: CONFIGURATION FLAGS 3

BITS DESCRIPTION

31:16 RESERVED

15:0 HS Detach Time (HS_DETACH)

See Section 15.1.23, "USB Configuration Register 2 (USB_CFG2)," on page 172

TABLE 10-14: GPIO CONFIGURATION

BITS DESCRIPTION

63:60 RESERVED

59:48 GPIO 0-11 Enable

47:44 RESERVED

43:32 GPIO 0-11 Buffer

31:28 RESERVED

27:16 GPIO 0-11 Direction

15:12 RESERVED

11:0 GPIO 0-11 Data

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 117

LAN7850

10.6 Customized Operation Without EEPROM

The device provides the capability to customize operation without the use of an EEPROM. Descriptor information and

initialization quantities normally fetched from EEPROM and used to initialize descriptors and elements of the System

Control and Status Registers may be specified via an alternate mechanism. This alternate mechanism involves the use

of the Descriptor RAM in conjunction with the Attribute Registers and select elements of the System Control and Status

Registers. The software device driver orchestrates the process by performing the following actions in the order indi-

cated:

•Initialization of SCSR Elements in Lieu of EEPROM Load

•Attribute Register Initialization

•Descriptor RAM Initialization

•Enable Descriptor RAM and Attribute Registers as Source

•Inhibit Reset of Select SCSR Elements

The following subsections explain these actions. The attribute registers must be written prior to initializing the Descriptor

RAM. Failure to do this will prevent the PWR_SEL and RMT_WKUP flags from being overwritten by the bmAttributes

of the Configuration Descriptor.

10.6.1 INITIALIZATION OF SCSR ELEMENTS IN LIEU OF EEPROM LOAD

During EEPROM operation, the following register fields are initialized by the hardware using the values contained in the

EEPROM. In the absence of an EEPROM, or configured OTP, the software device driver must initialize these quantities

as required for the application.

•MAC Receive Address High Register (RX_ADDRH) and MAC Receive Address Low Register (RX_ADDRL)

•SUSPEND_N Pin Select (SUSPEND_N_SEL) bit of the Hardware Configuration Register (HW_CFG)

•SUSPEND_N Pin Polarity (SUSPEND_N _POL) bit of the Hardware Configuration Register (HW_CFG)

•Device Speed to Connect (DEV_SPEED) bit of the USB Configuration Register 0 (USB_CFG0)

•HS Output Current (PHY_BOOST) field of the USB 2.0 AFE Test Register (USB2_TEST)

•LPM Capability (LPM_CAP) field of the USB Configuration Register 0 (USB_CFG0)

•Remote Wakeup Support (RMT_WKP) field of the USB Configuration Register 0 (USB_CFG0)

•Power Method (PWR_SEL) field of the USB Configuration Register 0 (USB_CFG0)

•Automatic Duplex Detection (ADD) bit of the MAC Control Register (MAC_CR)

•Automatic Speed Detection (ASD) bit of the MAC Control Register (MAC_CR)

•GPIO Enable (GPIOEN), GPIO Buffer Type (GPIOBUF), GPIO Direction (GPIODIR) and GPIO Data (GPIOD) of

the General Purpose IO Configuration 0 Register (GPIO_CFG0)

•GPIO Enable (GPIOEN), GPIO Buffer Type (GPIOBUF), GPIO Direction (GPIODIR) and GPIO Data (GPIOD) of

the General Purpose IO Configuration 1 Register (GPIO_CFG1)

•GPIO Wake 0-11 (GPIOWK[11:0]) of the General Purpose IO Wake Enable and Polarity Register (GPIO_WAKE)

•GPIO Polarity 0-11 (GPIOPOL[11:0]) of the General Purpose IO Wake Enable and Polarity Register (GPI-

O_WAKE)

•TX Swing (TxSwing), TX Margin (TxMargin), TX Deemphasis (TxDeemphasis), Elasticity Buffer Mode (Elasticity-

BufferMode) of PIPE Control Register (PIPE_CTL)

•LED3 Enable (LED3_EN) bit of the Hardware Configuration Register (HW_CFG), if desired

•LED2 Enable (LED2_EN) bit of the Hardware Configuration Register (HW_CFG), if desired

•LED1 Enable (LED1_EN) bit of the Hardware Configuration Register (HW_CFG), if desired

•LED0 Enable (LED0_EN) bit of the Hardware Configuration Register (HW_CFG), if desired

•LED3 Configuration, LED2 Configuration, LED2 Configuration, LED1 Configuration, LED0 Configuration of the

Ethernet PHY LED Mode Select Register

• All fields of the Ethernet PHY LED Behavior Register

For a description of PME operation see Section 14.0, "Power Management Event (PME) Operation" and the Flag Attri-

butes Register (FLAG_ATTR).

LAN7850

DS00001993D-page 118  2015 - 2017 Microchip Technology Inc.

10.6.2 ATTRIBUTE REGISTER INITIALIZATION

The Attribute Registers are as follows:

•BOS Descriptor Attributes Register (BOS_ATTR)

•HS Descriptor Attributes Register (HS_ATTR)

•FS Descriptor Attributes Register (FS_ATTR)

•String Attributes Register 0 (STRNG_ATTR0)

•String Attributes Register 1 (STRNG_ATTR1)

•Flag Attributes Register (FLAG_ATTR)

All of these registers contain fields defining the lengths of the descriptors or block contents written into the Descriptor

RAM. If an item is not written into the Descriptor RAM, the associated entry in the Attributes Register must be written

as 0. Writing an erroneous or illegal length will result in untoward operation and unexpected results.

10.6.3 DESCRIPTOR RAM INITIALIZATION

The Descriptor RAM contents are initialized using the Data Port registers. The Data Port registers are used to select the

Descriptor RAM and write the descriptor elements into it. The Descriptor RAM is 512 bytes in length. Every descriptor/

block written into the Descriptor RAM must be DWORD aligned. The Attribute Registers discussed in Section 10.6.2

must be written with the length of the descriptors written into the Descriptor RAM. If a descriptor/block is not used, hence

not written into Descriptor RAM, its length must be written as 0 into the associated Attribute Register.

The descriptors/blocks must be written in the following order, starting at address 0 of the RAM and observing the

DWORD alignment rule:

• Language ID (2 bytes)

• Manufacturing String Descriptor (String Index 1)

• Product Name String Descriptor (String Index 2)

• Serial Number String Descriptor (String Index 3)

• Configuration String Descriptor (String Index 4)

• Interface String Descriptor (String Index 5)

• BOS Block

• HS Device Descriptor

• HS Configuration Descriptor

• FS Device Descriptor

• FS Configuration Descriptor

An example of Descriptor RAM use is illustrated in Figure 10-9. In it, the BOS Block contains the BOS Descriptor (5

bytes), and a USB 2.0 Extension Descriptor (7 bytes) and a reserved 10 bytes for a total length of 22 bytes.

As in the case of descriptors specified in EEPROM, the following restrictions apply to descriptors written into Descriptor

RAM:

1. For Device Descriptors, the only valid values for the length are 0 and 18. The descriptor size for the Device

Note: The software device driver must initialize these registers prior to initializing the Descriptor RAM.

The bmAttributes field of the HS, and FS descriptors in descriptor RAM (if present) must be consistent with

the contents of the Power Method (PWR_SEL) field of the USB Configuration Register 0 (USB_CFG0).

Note: The Attribute Registers must be initialized before the Descriptor RAM.

Address 0 of the Descriptor RAM is always reserved for the Language ID, even if it will not be supported.

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 119

LAN7850

Descriptors specified in the Descriptor RAM is a don't care and always overwritten by HW to 0x12 when trans-

mitting the descriptor to the host.

2. The descriptor type for Device Descriptors specified in the Descriptor RAM is a don't care and is always overwrit-

ten by HW to 0x1 when transmitting the descriptor to the host.

3. For the Configuration and Interface descriptor, the only valid values for the length are 0 and 18. The descriptor

size for the Configuration Descriptors specified in the Descriptor RAM is a don't care and always overwritten by

HW to 0x12 when transmitting the descriptor to the host.

4. The descriptor type for the Configuration Descriptors specified in the Descriptor RAM is a don't care and always

overwritten by HW to 0x2 when transmitting the descriptor to the host.

5. If a string descriptor does not exist in the Descriptor RAM, the referencing descriptor must contain 00h for the

respective string index field.

6. If all string descriptor lengths are zero, then a Language ID will not be supported.

Note: The first entry in the Descriptor RAM is always reserved for the Language ID, even if it will not be supported.

Descriptors having bMaxPacketSize other than 40h when operating in Full-Speed or High-Speed mode will

result in unwanted behavior and untoward results. Descriptors having bNumConfigurations with values

other than 1 will result in unwanted behavior and untoward results.

LAN7850

DS00001993D-page 120  2015 - 2017 Microchip Technology Inc.

FIGURE 10-9: DESCRIPTOR RAM EXAMPLE

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 121

LAN7850

10.6.4 ENABLE DESCRIPTOR RAM AND ATTRIBUTE REGISTERS AS SOURCE

The EEPROM Emulation Enable (EEM) bit of the Hardware Configuration Register (HW_CFG) must be set by the soft-

ware device driver to use the Descriptor RAM and the Attribute Registers for custom operation. Upon assertion of

EEPROM Emulation Enable (EEM), the hardware will utilize the Descriptor information contained in the Descriptor RAM,

the Attributes Registers, and the values of the items listed in Section 10.6.1 to facilitate custom operation.

10.6.5 INHIBIT RESET OF SELECT SCSR ELEMENTS

The software device driver must take care to ensure that the contents of the Descriptor RAM and SCSR register content

critical to custom operation using Descriptor RAM are preserved across reset operations other than POR. The driver

must configure the Reset Protection (RST_PROTECT) bit of the Hardware Configuration Register (HW_CFG) in order

to accomplish this.

The following registers have contents that can be preserved across all resets other than POR. Consult the register’s

description for additional details.

• Descriptor RAM (Section 10.6.3)

• Attribute Registers (Section 10.6.2)

•MAC Receive Address High Register (RX_ADDRH) and MAC Receive Address Low Register (RX_ADDRL)

•Hardware Configuration Register (HW_CFG)

•USB Configuration Register 0 (USB_CFG0)

•USB Configuration Register 1 (USB_CFG1)

•USB Configuration Register 2 (USB_CFG2)

•MAC Control Register (MAC_CR)

•Flag Attributes Register (FLAG_ATTR)

•General Purpose IO Wake Enable and Polarity Register (GPIO_WAKE)

•Ethernet PHY LED Mode Select Register

•PIPE Control Register (PIPE_CTL)

LAN7850

DS00001993D-page 122  2015 - 2017 Microchip Technology Inc.

11.0 ONE TIME PROGRAMMABLE (OTP) MEMORY

The device integrates a 1K One Time Programmable (OTP) memory to store various configuration data and serve as

an EEPROM replacement to reduce bill of material costs. OTP programming is supported over USB to facilitate end

user customization. Microchip provides a comprehensive software programming tool, Pro-Touch, for configuring the

device’s OTP memory. All OTP configuration is to be performed via the Pro-Touch programming tool. For additional

information on the Pro-Touch programming tool, refer to www.microchip.com.

OTP may potentially co-exist with an external EEPROM. Refer to Section 10.1, "EEPROM and OTP Relationship," on

page 99 for details.

11.1 OTP Format

The OTP format is based upon the format specified for the EEPROM. See Section 10.4, "EEPROM Format," on

page 105 for details.

As with the EEPROM, a signature is required to define whether or not the OTP has been programmed. If the value 0xF3

or 0xF7 is found at byte 0, the OTP shall be determined to be programmed.

A signature of 0xF3 indicates that the device is configured using values (Mac Address and subsequent as per EEPROM

Contents) from byte offset 1 in the OTP. A value of 0xF7 indicates that the device is configured loading values (Mac

Address and subsequent as per EEPROM Contents) from byte offset 0x101 in the OTP.

APPLICATION NOTE: The dual signatures enable a mechanism for the OTP to be programmed twice. This may

prove useful for initial bring up of the device where inadvertently mis-programming the device

could render it non-functional. This scheme requires that when an offset of 0xF3 is used that

only the first 255 bytes of the OTP are programmed. In the event that the OTP was mis-

configured the device can be “saved” by changing the signature on byte 0 from 0xF3 to 0xF7

and writing the new content starting at byte 0x101.

APPLICATION NOTE: Software must ensure that the offsets are appropriately configured to support the dual 256

byte partitioning when this mode of operation is desired. Even when using 0xF7 the offsets

are still from 0x0.

As with the EEPROM, if a valid signature is not present at byte 0, the OTP shall be deemed to not be programmed and

the device will not use it for configuration.

11.2 OTP Interrupt

The OTP module’s interrupt has been mapped into the Interrupt Endpoint as well as the Interrupt Status Register

(INT_STS).

OTP program operations take a significant amount of time and therefore are posted. A general rule of thumb is 5 ms/

bit. The completion of a program operation is signified by the OTP Write Done Interrupt (OTP_WR_DONE_INT).

11.3 OTP System Reset

Certain system reset events cause the contents of the OTP to be re-loaded, as detailed in Section 12.0, "Resets". The

OTP is powered up initially after a reset event and its contents automatically loaded into the device’s Descriptor RAM

and various configuration CSRs. See Section 12.0, "Resets" for further details.

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 123

LAN7850

12.0 RESETS

The device provides the following chip-level reset sources:

•Power-On Reset (POR)

•External Chip Reset (RESET_N)

•Lite Reset (LRST)

•Soft Reset (SRST)

•USB Reset

•VBUS_DET

Additionally, the device provides a non-chip-level Ethernet PHY Software Reset.

12.1 Power-On Reset (POR)

A Power-On Reset (POR) occurs whenever power is initially applied to the device, or if power is removed and reapplied

to the device. A timer within the device will assert the internal reset for approximately 20 ms. EEPROM/OTP contents

are loaded by this reset.

The POR is a combination of five separate POR circuits that measure the voltage on the following domains:

• Ethernet PHY 1.2 V

• Ethernet PHY 2.5 V

• USB PHY 1.2 V

• USB PHY 3.3 V

• VDDVARIO

After power up, the POR initially de-asserts after the Rising Threshold is passed. In the event that the supply drops

below the Falling Threshold the POR asserts. The POR stays asserted until the Rising Threshold is once again crossed.

The rising and falling thresholds are listed in Table 12-1.

APPLICATION NOTE: The POR on VDDVARIO targets 1.8 V I/O operation. If a higher voltage is used, than an

external POR may be required to provide full brown out detection on the I/O domain.

12.2 External Chip Reset (RESET_N)

A hardware reset will occur when the RESET_N pin is driven low. Assertion of RESET_N is not required at power-on.

However, if used, RESET_N must be driven low for a minimum period as defined in Section 16.6.2, "RESET_N Timing,"

on page 267. The RESET_N pin is pulled-high internally but must be connected externally to VDDVARIO if unused.

TABLE 12-1: POR THRESHOLDS

POR RISING THRESHOLD FALLING THRESHOLD

Ethernet PHY 1.2V 0.9 V 0.8 V

Ethernet PHY 2.5V 2.0 V 1.8 V

USB PHY 1.2V 0.9 V 0.8 V

USB PHY 3.3V 2.7 V 2.35 V

VDDVARIO 1.45 V 1.25 V

Note: If configured, the EEPROM/OTP contents are reloaded by this reset.

LAN7850

DS00001993D-page 124  2015 - 2017 Microchip Technology Inc.

12.3 Lite Reset (LRST)

This reset is initiated via the Soft Lite Reset (LRST) bit in the Hardware Configuration Register (HW_CFG). It will reset

the entire device with the exception of the USB Device Controller and the USB PHY. The PLL is not turned off during a

Lite Reset.

APPLICATION NOTE: Prior to issuing an LRST, system software shall stop activity on the device’s USB pipes. After

the LRST is issued, the system software shall restart the pipes. This process includes

sending CLEAR_FEATURE(ENDPOINT_HALT) for the device pipes, which causes data

toggle on the device side to be reset. The data toggle must also be reset for each pipe on

the host side.

12.4 Soft Reset (SRST)

Software initiated reset is accomplished by setting the Soft Reset (SRST) bit of Hardware Configuration Register

(HW_CFG). After this bit is set, the device soft detaches from the USB bus. The duration of the detachment is typically

10 ms for HS/FS. Upon expiration of this time, the device will completely reset itself and re-attach to the USB bus.

APPLICATION NOTE: The detachment time is programmable via the HS Detach Time (HS_DETACH) fields in USB

Configuration Register 2 (USB_CFG2).

12.5 USB Reset

A USB reset causes a reset of the entire device with the exception of the USB Device Controller and the USB PHY. The

USB PLL is not turned off. After a USB reset, the Device Ready (READY) bit in the Power Management Control Register

(PMT_CTL) can be read by the Host and will read back a ‘0’ until the EEPROM/OTP contents are loaded (provided one

is present). The device than can be configured via its control registers.

12.6 VBUS_DET

The removal of USB power causes the device to transition to the UNPOWERED state. The chip is held in reset while in

the UNPOWERED state.

12.7 Ethernet PHY Software Reset

An Ethernet PHY software reset is provided via the PHY Reset (PHY_RST) bit in the Power Management Control Reg-

ister (PMT_CTL). This reset is not a chip-level reset and resets only the Ethernet PHY. When asserted, the Gigabit

Ethernet PHY is reset for a minimum of 2 ms.

Note: This reset does not cause the USB contents from the EEPROM/OTP to be reloaded.

This reset does not place the device into the Unconfigured state.

The Soft Lite Reset (LRST) bit does not clear control register bits marked as NALR.

Note: If configured, the EEPROM/OTP contents are reloaded by this reset.

Note: This reset does not cause the entire contents from the EEPROM or OTP to be reloaded. Only the MAC

address is reloaded.

Note: After VBUS_DET is asserted, the contents of the EEPROM/OTP are reloaded, if configured.

Note: After transitioning out of the UNPOWERED state, the internal Ethernet PHY remains in reset to minimize

power.

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 125

LAN7850

The Device Ready (READY) bit in the Power Management Control Register (PMT_CTL) asserts when the Ethernet PHY

is functional. It may take over 100 ms for the device to become operational after this reset, depending on the state of

Disable Wait Analog Voltage Reference Stable (DIS_WAIT_ANA_REF) in Power Management Control Register

(PMT_CTL).

LAN7850

DS00001993D-page 126  2015 - 2017 Microchip Technology Inc.

13.0 CLOCKS AND POWER MANAGEMENT (CPM)

The Clocks and Power Management (CPM) block is responsible for generating the device clocks and controlling the

power management logic. CPM functions include:

• Enabling the host to place the device in a reduced power state, e.g. suspend state, by disabling internal clocks

and powering down various device blocks, including PLLs.

• Providing detection of various wakeup events.

• Providing a host-readable READY flag which is set when the device is in the NORMAL state.

• Controlling the loading of OTP or EEPROM values after a system reset.

• Supporting USB 2.0 Suspend

• Supporting LPM extensions

These functions are detailed in the following sub-sections:

•Device Clocking

•Power States

•Suspend States

•Wake Events

13.1 Device Clocking

The device requires a fixed-frequency 25 MHz clock source. This is typically provided by attaching a 25 MHz crystal to

the XI and XO pins. The clock can optionally be provided by driving the XI input pin with a single-ended 25 MHz clock

source. If a single-ended source is selected, the clock input must run continuously for normal device operation.

Internally, the device generates its required clocks with a phase-locked loop (PLL). It reduces its power consumption in

several of its operating states by disabling its internal PLL and derivative clocks. The 25 MHz clock remains operational

in all states where power is applied.

Refer to Section 16.7, "Clock Circuit," on page 269 for additional clocking requirements.

13.2 Power States

The following power states are supported:

• UNPOWERED

• NORMAL (Unconfigured and Configured)

• Suspend States (SUSPEND0, SUSPEND1, SUSPEND2, and SUSPEND3)

Figure 13-1 details the device power states and transitions. In order to simplify Figure 13-1, the USB Suspend and USB

Resume transitions are a superset of the following conditions:

•USB Suspend: USB 2.0 Suspend

•USB Resume: USB 2.0 Resume, transition to LPM L0

Additionally, only a subset of wake events are shown, due to space constraints. A detailed wakeup description is pro-

vided in the following sub-sections.

Note: It is not possible to transition from SUSPEND2 to NORMAL Configured if SUSPEND2 was entered via a

transition from NORMAL Unconfigured.

When the device is bus powered, VBUS_DET is externally tied to 1b. Therefore, the UNPOWERED state

only has meaning for self powered operation.

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 127

LAN7850

13.2.1 UNPOWERED STATE

The UNPOWERED state provides a mechanism for the device to conserve power when VBUS_DET is not connected

and the device is self powered.

The device initially enters the UNPOWERED state when a system reset occurs and USB power is not detected. This

state persists until the VBUS_DET is asserted. The UNPOWERED state is alternatively entered whenever VBUS_DET

de-asserts.

In the UNPOWERED state, the crystal oscillator and PLLs are turned off and the Ethernet PHY is disabled. Assertion

of VBUS_DET causes the device to enable the crystal oscillator and PLLs. When PLLs are stable, the device transitions

to the NORMAL-Unconfigured state.

In order to make the device fully operational, the host must configure the device, which places it in the NORMAL Con-

figured state.

13.2.2 NORMAL STATE

The NORMAL state is the functional state of the device. The are two versions of this state, NORMAL-Configured and

NORMAL-Unconfigured. In the configured variation all modules are enabled. The Unconfigured variation has only a

subset of the modules enabled to allow for power savings.

The NORMAL state is entered by any of the following methods.

• A system reset and VBUS_DET is asserted

• The device is in the UNPOWERED state and VBUS_DET is asserted

• The device is in a SUSPENDx state and the host issues resume signaling.

• The device is in a SUSPENDx state and a wake event is detected.

FIGURE 13-1: POWER STATES

LAN7850

DS00001993D-page 128  2015 - 2017 Microchip Technology Inc.

13.2.2.1 NORMAL-Unconfigured

Upon initially entering the NORMAL-Unconfigured state, the device is not configured. While unconfigured, the device

will only draw up to 100 mA per the USB 2.0 Specification. After being configured, an additional 400 mA may be con-

sumed when operating in USB 2.0 mode.

In order to maximize power savings in NORMAL-Unconfigured mode, the Gigabit Ethernet PHY is held in reset.

The device moves from the Normal-Unconfigured to Normal-Configured when directed by the host via the SetConfigu-

ration request. Likewise, the host can move the device back into the Normal-Unconfigured state with this request.

13.2.2.2 NORMAL-Configured

This is the fully operational state of the device where all clocking resources and analog blocks are enabled and func-

tional.

13.2.2.3 Reset Operation

After a system reset, the device is moved into the NORMAL-Unconfigured state (unless the device is self-powered and

VBUS_DET = 0). The host must then configure the device.

The following steps illustrate the process for a POR. The steps vary depending on the reset and the initial state of the

device.

13.2.2.4 Suspend Operation

When returning to the NORMAL state from a SUSPENDx state, the USB context is maintained. After entering the NOR-

MAL-Configured state, the Device Ready (READY) bit in the Power Management Control Register (PMT_CTL) is

asserted after the PHY is operational.

13.3 Suspend States

The suspend state is entered after the USB Host places the device in low power state as defined below:

• USB 2.0 Suspend (LPM L2)

There are several variations of the suspend state available. Each state offers different options in terms of power con-

sumption and remote wakeup support.

A suspend state can only be entered via a transition from the NORMAL state. The Suspend Mode (SUSPEND_MODE)

field of the Power Management Control Register (PMT_CTL) indicates which suspend state is to be used. A transfer

back to the NORMAL state occurs when requested by the host (e.g. USB Resume signaling) or a configured wakeup

event is detected by the device.

When the device is in the NORMAL-Unconfigured state, it is only possible to transition to the SUSPEND2 state. After

being taken out of suspend, the device transitions back to NORMAL-Unconfigured.

13.3.1 RESET FROM SUSPEND

All suspend states must respond to USB Reset and RESET_N pin assertion. The application of these resets result in

the device being re-initialized and placed into the NORMAL-Unconfigured state.

Note: If the originating suspend state is SUSPEND2, then the host is required to reinitialize the Ethernet PHY

registers.

Note: If the device is deconfigured, then Suspend Mode (SUSPEND_MODE) resets to 10b.

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 129

LAN7850

13.3.2 SUSPEND0

This state is selected when the Suspend Mode (SUSPEND_MODE) field of the Power Management Control Register

(PMT_CTL) is set to 00b.

In this state the device can optionally be programmed to detect GPIO wake, Wake-On-LAN event, Magic Packet, PHY

Link Status, EEE wake, etc.. Refer to Section 13.4.2, "Enabling Wake Events," on page 133 for details on how to pro-

gram events that cause resumption from the SUSPEND0 state.

To maximize power savings the PLLs are shutdown. The 25 MHz crystal oscillator remains operational to clock the MAC

and the Gigabit Ethernet PHY.

The detection of a WOL event causes the PLL, as required for the established USB link, to be turned on and all output

clocks to be enabled.

APPLICATION NOTE: Additional power savings can be gained if the Ethernet Link is forced to negotiate to a lower

speed. However, this may have additional drawbacks. Studies done with drivers for prior

controllers have shown latencies in excess of four seconds.

13.3.3 SUSPEND1

This state is logically equivalent to SUSPEND0 and is selected when the Suspend Mode (SUSPEND_MODE) field of

the Power Management Control Register (PMT_CTL) is set to 00b.

13.3.4 SUSPEND2

This state is selected when the Suspend Mode (SUSPEND_MODE) field of the Power Management Control Register

(PMT_CTL) is set to 10b. SUSPEND2 is the default suspend mode.

SUSPEND2 consumes the least power of the suspend state options. It is the only option that meets the USB 2.5 mA

suspend power consumption requirement. In this state, GPIO assertion is the only remote wakeup source supported.

13.3.5 SUSPEND3

This state is selected when the Suspend Mode (SUSPEND_MODE) field of the Power Management Control Register

(PMT_CTL) is set to 11b.

In this suspend state, most clocks in the device are enabled and power consumption is similar to the NORMAL-Config-

ured state. Power savings is realized only in powering down the USB AFEs which happens automatically after the host

software moves the device into USB Suspend. The target for power savings in this state is the host CPU. This suspend

state shall be used for AOAC support and/or whenever the packet event that caused the wake event must be saved.

Refer to Section 13.4.2.1, "Enabling GPIO Wake Events," on page 133, Section 13.4.2.4, "Enabling “GOOD Frame”

Wake Events," on page 134, Section 13.4.2.2, "Enabling WOL Wake Events," on page 133, and Section 13.4.2.5,

"Enabling “AOAC” Wake events" for detailed instructions on how to program events that cause resumption from the

SUSPEND3 state. SUSPEND3 can also be exited when Energy Efficient Ethernet RX Wake (EEE_RX_WAKE) is set

with Energy Efficient Ethernet RX Wake Enable (EEE_RX_WAKE_EN) set or when Energy Efficient Ethernet TX Wake

(EEE_TX_WAKE) is set with Energy Efficient Ethernet TX Wake Enable (EEE_TX_WAKE_EN) set.

Unlike other suspend states, there is the capability to store the frame that triggered the wakeup into the RX FIFO. This

is discussed further in Section 13.4.2.5, "Enabling “AOAC” Wake events". After the wakeup frame is received, all sub-

sequent frames that pass the filtering constraints in the MAC and Receive Filtering Engine (RFE) are written into the RX

FIFO as well. This feature allows the OS to determine the cause of the wake event and report the packet and any fol-

lowing ones that were received while the USB bus has not yet been resumed.

To enable an aggressive suspend policy by the host, SUSPEND3 supports the concept of “Good Frame” wake-ups. In

this scenario any non-errored receive frame that passes the RFE filters causes a wakeup and is stored in the RX FIFO.

All subsequent frames are also written into the FIFO. Utilizing the RFE filter rules in the context of a wakeup is enabled

by the RFE Wakeup Frame Received (RFE_WAKE_FR) bit.

Note: Software may optionally enable ARP offload or NS offload in this state.

Note: It is appropriate to enable ARP offload and NS offload in this state, though it is completely under software

control and not enforced by hardware. For AOAC support, that is mandatory, and normally executed by the

operating system.

LAN7850

DS00001993D-page 130  2015 - 2017 Microchip Technology Inc.

13.3.6 NETDETACH

NetDetach is a mode of operation where the device detaches from the USB bus after the Ethernet cable is disconnected.

It is typically used in environments that cannot implement selective suspend when the link is down (such Windows OS

prior to Windows 8). This is advantageous for mobile devices, as an attached USB device prevents the host CPU from

entering the C3 state. Allowing the CPU to enter the C3 state maximizes battery life.

When detached, the device power state is essentially the same as the SUSPEND0 state. After the Ethernet cable is

reconnected, or a programmed GPIO pin asserts, the device automatically attaches to the USB bus.

NetDetach requires assistance of the host software driver. The driver will monitor the link status of the Ethernet PHY

and program the part appropriately to detach and re-attach to the USB bus upon link change. The following steps illus-

trate this process:

1. Ethernet cable is not detected.

2. Driver detects assertion of the PHY_INT bit via the interrupt control endpoint. The driver may also detect PHY

interrupt assertion by polling the Interrupt Status Register (INT_STS). It is also valid to only poll the PHY's link

status bit without looking at interrupt endpoint or interrupt status.

3. Driver reads the respective Ethernet PHY CSRs and determines that the link has been lost.

4. Driver programs the device and Ethernet PHY to detect Link Status Change from link down to link up.

5. Driver sets the NetDetach Enable (NETDET_EN) bit in the Hardware Configuration Register (HW_CFG). The

CONNECT function may also be enabled via the Hardware Configuration Register (HW_CFG).

6. The device then detaches from the USB bus and disables the PLLs. The driver is unloaded at this point and can

no longer communicate with the device.

7. At some point in the future, the Ethernet cable is reconnected and link is regained, or an appropriately configured

GPIO pin is asserted.

8. The device enables the USB PLLs and AFEs.

9. The device attaches to the USB bus.

10. The driver is loaded and the device is configured by the driver. The driver examines the NetDetach Status (NET-

DET_STS) bit in the Hardware Configuration Register (HW_CFG) to determine if it was reloaded as a result of

coming back from a NetDetach operation or for some other event. The driver may also disable the CONNECT

function if previously enabled.

APPLICATION NOTE: In order to maximize power savings it is recommended that the driver utilize the Enhanced

PHY power down feature of the Ethernet PHY (via Configuration Flags 0). Further power

savings may be obtained by forcing the link to 100 Mbps.

APPLICATION NOTE: GPIO wakes are supported in this state.

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 131

LAN7850

13.4 Wake Events

The following events can wake up/enable the device.

• USB Host Resume

•VBUS_DET assertion

• Wakeup Frame

• Magic Packet

• PHY Link Change

• EEE Wake

• Global Unicast frame

• Broadcast frame

• Perfect DA Match

• TCP SYN Packet

• “Good” Frame

• GPIO[11:0]

Table 13-1 illustrates the wake events permitted in each of the power states.

The occurrence of a GPIO wake event causes the corresponding bit in the Interrupt Status Register (INT_STS) to be

set. Before suspending the device, the host must ensure that any pending wake events are cleared. Otherwise, the

device will immediately be awakened after being suspended.

TABLE 13-1: POWER STATUS/WAKE EVENT MAPPING

Wake Event SUSPEND0/

SUSPEND1 SUSPEND2 SUSPEND3 Unpowered PME Mode NetDetach

USB Host Resume Signaling YES YES YES NO NO NO

VBUS Detection NO NO NO YES NO NO

Magic Packet YES NO YES NO YES NO

Wakeup Frame YES NO YES NO YES NO

Broadcast Frame YES NO YES NO YES NO

Perfect DA Match of Physical Address YES NO YES NO YES NO

Good Frame NO NO YES NO NO NO

TCP SYN YES NO YES NO NO NO

EEE RX Wake YES NO YES NO NO NO

EEE TX Wake YES NO YES NO NO NO

PHY Link Change (Internal PHY) YES NO YES NO YES YES

GPIO[10:0] YES YES YES NO YES YES

LAN7850

DS00001993D-page 132  2015 - 2017 Microchip Technology Inc.

13.4.1 DETECTING WAKEUP EVENTS

The device supports the ability to generate remote wakeup events. A simplified diagram of the wake event detection

logic is shown in Figure 13-2.

When an enabled remote wake event is detected, the USB Device Controller notifies the host. For HS mode, remote

wakeup signaling is issued. The device can also de-assert the SUSPEND_N pin, depending on its configuration.

In addition to the above, the device also supports remote wakeup. In HS/FS mode the DEVICE_REMOTE_WAKEUP

feature must be set.

FIGURE 13-2: WAKE EVENT DETECTION BLOCK DIAGRAM

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 133

LAN7850

13.4.2 ENABLING WAKE EVENTS

The following sub-sections detail the procedure for enabling various wake events:

•Enabling GPIO Wake Events

•Enabling WOL Wake Events

•Enabling Link status Change Wake Events

•Enabling “GOOD Frame” Wake Events

•Enabling “AOAC” Wake events

13.4.2.1 Enabling GPIO Wake Events

The Host system shall perform the following steps to enable the device to issue a remote wake event on detection of a

GPIO wake.

1. The GPIO pin is programmed to facilitate generation of the wake event.The respective GPIO must be enabled

via GPIO Enable (GPIOEN) of General Purpose IO Configuration 0 Register (GPIO_CFG0) or GPIO Enable

(GPIOEN) of General Purpose IO Configuration 1 Register (GPIO_CFG1).

2. The GPIO pin must be enabled for wakeup and its desired polarity specified in the GPIO Wake 0-11 (GPI-

OWK[11:0]) and GPIO Polarity 0-11 (GPIOPOL[11:0]) fields, respectively, of the General Purpose IO Wake

Enable and Polarity Register (GPIO_WAKE).

3. The Host places the device in the any one of the SUSPEND states by setting the Suspend Mode (SUSPEND_-

MODE) field of the Power Management Control Register (PMT_CTL) to indicate the desired suspend state, then

sends suspend signaling.

4. On detection of an enabled GPIO wake event, the device will transition back to the NORMAL state and signal a

remote wake event. The Host may then examine the GPIO [11:0] (GPIOx_INT_WK) status bits of the Wakeup

Source Register (WK_SRC) to determine the source of the wakeup.

13.4.2.2 Enabling WOL Wake Events

The Host system shall perform the following steps to enable the device to assert a remote wake event on detection of

a Wake on LAN event.

1. All transmit and receive operations must be halted: All pending Ethernet TX and RX operations must be com-

pleted. The MAC RX and TX paths are disabled.

2. The MAC must be configured to detect the desired wake event. This process is explained in Section 8.3.2.2,

"Wakeup Frame Detection," on page 78 for Wakeup Frames and in Section 8.3.2.3, "Magic Packet Detection,"

on page 80 for Magic Packets. Configuring Perfect DA and Broadcast Frame wakeup detection is analogous and

requires the Perfect DA Frame Received (PFDA_FR) or Broadcast Wakeup Enable (BCAST_EN) bit to be set in

the Wakeup Control and Status Register 1 (WUCSR1).

3. Bit 1 of the Wakeup Status (WUPS[1]) in the Power Management Control Register (PMT_CTL) must be cleared

since a set bit will cause the immediate assertion of wake event when the Wake-On-LAN Enable (WOL_EN) bit

is set. The WUPS[1] bit will not clear if the internal MAC wakeup event is asserted.

4. Set the Wake-On-LAN Enable (WOL_EN) bit in the Power Management Control Register (PMT_CTL).

5. The MAC RX path is re-enabled.

6. The Host places the device in SUSPEND0 or SUSPEND3 state by appropriately setting the Suspend Mode

(SUSPEND_MODE) field in the Power Management Control Register (PMT_CTL), to indicate the desired sus-

pend state. The host then sends suspend signaling.

On detection of an enabled event, the device will transition back to the NORMAL state and signal a wake event. Upon

discovering wakeup occurred, the status bits of the Wakeup Source Register (WK_SRC) may be examined to determine

the particular event that caused the wakeup.

LAN7850

DS00001993D-page 134  2015 - 2017 Microchip Technology Inc.

13.4.2.3 Enabling Link status Change Wake Events

The Host system must perform the following steps to enable the device to assert a remote_wake event on detection of

an Ethernet link status change or Energy Detection.

1. Ethernet cable is not detected or has become disconnected.

2. All transmit and receive operations must be halted: All pending Ethernet TX and RX operations must be com-

pleted. The MAC RX and TX paths are disabled.

3. The appropriate CSRs are configured in the PHY to enable the Energy and Link Status Change detection. The

Link State-Change Interrupt Mask is unmasked and the PHY asserts its interrupt when the condition is detected.

4. Bit 0 of the Wakeup Status (WUPS[0]) in the Power Management Control Register (PMT_CTL) must be cleared,

since a set bit will cause the immediate assertion of wake event when PHY Interrupt Enable (PHY_WAKE_EN)

is set. The WUPS[0] bit will not clear if the internal PHY interrupt is asserted.

5. Set the PHY Interrupt Enable (PHY_WAKE_EN) bit in the Power Management Control Register (PMT_CTL).

6. The Host places the device in SUSPEND0 or SUSPEND1 state by appropriately setting the Suspend Mode

(SUSPEND_MODE) field in the Power Management Control Register (PMT_CTL), to indicate the desired sus-

pend state, then sends suspend signaling.

7. On detection of Ethernet activity, the device will signal a remote wake event and transition back to the NORMAL

state upon examining the Wakeup Source Register (WK_SRC) the software can know the source was a link

change and process it accordingly.

13.4.2.4 Enabling “GOOD Frame” Wake Events

The Host system must perform the following steps to enable the device to initiate a remote wake event on detection of

a “Good Frame”. A “Good Frame” being an Ethernet frame that is not corrupted and passes the RFE filter rules as

enabled by the Receive Filtering Engine Control Register (RFE_CTL).

After reception of the “Good Frame” all valid subsequent frames received are placed in the Receive FIFO. The frame

that caused the “Good Frame” wake may also be stored in the FIFO if Store Wakeup Frame (STORE_WAKE) is set.

1. All transmit and receive operations must be halted: All pending Ethernet TX and RX operations must be com-

pleted. The MAC RX and TX paths are disabled.

2. Frame filtering is configured by setting the desired constraints in the Receive Filtering Engine Control Register

(RFE_CTL). The RFE Wake Enable (RFE_WAKE_EN) is set in Wakeup Control and Status Register 1

(WUCSR1) as well as Wake-On-LAN Enable (WOL_EN) bit of the Power Management Control Register

(PMT_CTL) shall be set to zero.

3. The device may be configured to store the wakeup frame in the FCT RX FIFO by setting Store Wakeup Frame

(STORE_WAKE) in the Wakeup Control and Status Register 1 (WUCSR1).

4. Bit 1 of the Wakeup Status (WUPS[1]) in the Power Management Control Register (PMT_CTL) must be cleared

since a set bit will cause the immediate assertion of a wake event. The WUPS[1] bit will not clear if the internal

MAC wakeup event is asserted.

5. The MAC RX path is re-enabled.

6. The Host places the device in the SUSPEND3 state by setting the Suspend Mode (SUSPEND_MODE) field in

the Power Management Control Register (PMT_CTL), to indicate the desired suspend state, and then sends sus-

pend signaling.

7. On detection of a “Good Frame”, the device transitions back to the NORMAL state and signals a remote wake

event.

8. Upon discovering a wakeup occurred software shall examine the Wakeup Source Register (WK_SRC). Host soft-

ware shall perform the desired processing as a result of receiving the “Good Frame” which typically includes

passing the received packet up the normal receive path of the software stack.

13.4.2.5 Enabling “AOAC” Wake events

This section describes how to configure the device for AOAC operation.

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 135

LAN7850

After an extended period of idle time, as defined by the host OS, it is desirable to place the system in a deep sleep state.

In order to maximize the duration in which the system can stay in sleep the network interfaces, in this case Ethernet,

are configured to offload several tasks that would normally awaken the host. The host is only awakened when a pre-

programmed wakeup pattern is received. The wakeup frame is stored in the RX FIFO to allow the OS to evaluate the

cause of the wakeup as well as pass it up the normal receive path (i.e. so that TCP socket connections can be main-

tained without retries).

The driver may consult Wakeup Frame Received bit of RX Command C to determine which packet in the RX FIFO insti-

gated the wakeup event. It is not guaranteed that the first packet written into the FIFO caused the wakeup. It is possible

for a data frame to have been written into the FIFO while the part is being suspended.

All frames received after wakeup frame are also stored in the FIFO. However these frames must also pass any addi-

tional filtering rules programmed into the MAC and RFE as well a frame corruption checks (e.g. FCS).

APPLICATION NOTE: In order to minimize system latency to the full operational state, and allow an aggressive

suspend/resume policy, the Ethernet link should not be change (i.e. 100 Mbps mode when

Gigabit link exists).

1. All transmit and receive operations must be halted: All pending Ethernet TX and RX operations must be com-

pleted. The MAC RX and TX paths are disabled.

2. The MAC must be configured to detect the desired wake event. The wakeup filters are appropriately configured

by the host via the Wakeup Filter x Configuration Register (WUF_CFGx) and Wakeup Filter x Byte Mask Regis-

ters (WUF_MASKx). This process is explained in Section 8.3.2.2, "Wakeup Frame Detection," on page 78 for

Wakeup Frames. Other wake events such as TCP SYN or Magic Packet may also be enabled.

3. Bit 1 of the Wakeup Status (WUPS[1]) in the Power Management Control Register (PMT_CTL) must be cleared

since a set bit will cause the immediate assertion of wake event when the Wake-On-LAN Enable (WOL_EN) bit

is set. The WUPS[1] bit will not clear if the internal MAC wakeup event is asserted.

4. Set the Wake-On-LAN Enable (WOL_EN) bit in the Power Management Control Register (PMT_CTL).

5. The device shall be configured to store the wakeup frame in the FCT RX FIFO by setting Store Wakeup Frame

(STORE_WAKE) in the Wakeup Control and Status Register 1 (WUCSR1).

6. The device shall be configured to disable RFE filtering on wakeup frames by setting Always Pass Wakeup Frame

(PASS_WKP) in Receive Filtering Engine Control Register (RFE_CTL).

7. The device is configured to enable ARP and NS offloads. See Section 8.6, "ARP Offload," on page 85 and Sec-

tion 8.5, "Neighbor Solicitation (NS) Offload," on page 83 for details on how to configure these functions.

8. The MAC RX and TX paths are re-enabled.

9. The Host places the device in the SUSPEND3 state by setting the Suspend Mode (SUSPEND_MODE) field in

the Power Management Control Register (PMT_CTL) to 11b, to indicate the desired suspend state, then sends

suspend signaling.

10. On detection of an enabled wake event, the device transitions back to the NORMAL state and signals a remote

wake event. The software will then examine the Wakeup Source Register (WK_SRC) and perform the desired

processing which may include passing the packet up to the operating system if the wake event was due to recep-

tion of a WOL packet.

LAN7850

DS00001993D-page 136  2015 - 2017 Microchip Technology Inc.

14.0 POWER MANAGEMENT EVENT (PME) OPERATION

The device provides a mechanism for waking up a host system via the Power Management Event (PME) mode of oper-

ation. PME signaling is only available while the device is operating in the self powered mode and a properly configured

EEPROM is attached. Figure 14-1 illustrates a typical application.

The Host Processor is connected to a Chipset containing the Host USB Controller (HC). The USB Host Controller inter-

faces to the device via the USB signals. An Embedded Controller (EC) signals the Chipset and the Host processor to

power up via an Enable signal. The EC interfaces to the device via four signals. The PME_N signal is an input to the

EC from the device that indicates the occurrence of a wakeup event. The VBUS_DET output of the EC is used to indicate

bus power availability. The PME_CLEAR (RESET_N) signal is used to clear the PME. The PME_MODE signal is sam-

pled by the device when PME_CLEAR (RESET_N) is de-asserted and is used by the device to determine whether it

should remain in PME mode or resume normal operation.

FIGURE 14-1: TYPICAL APPLICATION

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 137

LAN7850

The application scenario in Figure 14-1 assumes that the Host Processor and the Chipset are powered off, the EC is

operational, and the device is in PME mode, waiting for a wake event to occur. A wake event will result in the device

signaling a PME event to the EC, which will then wake up the Host Processor and Chipset via the Enable signal. The

EC asserts VBUS_DET after the USB bus is powered, sets PME_MODE to determine whether the device is to begin

normal operation or continue in PME mode, and asserts PME_CLEAR (RESET_N) to clear the PME.

APPLICATION NOTE: After de-assertion of PME_CLEAR, the device is configured. Configuration may entail

loading data from EEPROM or OTP if EEPROM-less mode is not used. The EC should not

sample PME_N during this time, which is dependent on the amount of data programmed in

OTP/EEPROM, as the polarity and behavior of PME_N has not yet been configured. For

EEPROM-less or OTP mode, the PME shall be valid within 1 ms. For an external EEPROM

this will be a function of the amount of data programmed in the EEPROM. If all 512 bytes

are programmed, the maximum delay is under 16 ms. Refer to Section 16.6.4, "EEPROM

Timing," on page 268 for additional details.

APPLICATION NOTE: If EEPROM-less mode is used, out-of-box wake is not supported. PME can only support

wakes with no EEPROM/OTP if the desired device’s wakes mentioned below are configured

by system software over USB before entering PME mode.

The following wake events are supported:

• Wakeup Pin(s)

The GPIO pins not reserved for PME handling have the capability to wake up the device when operating in PME

mode. In order for a GPIO to generate a wake event, it’s enable bit must be set in the GPIO[7:0] Wakeup Enables

and GPIO[11:8] Wakeup Enables fields of the EEPROM (or OTP). The polarity may also be set with GPIO[7:0]

Wakeup Polarity and GPIO[11:8] Wakeup Polarity.

• Magic Packet

Reception of a Magic Packet when in PME mode will result in a PME being asserted.

• WUFF

Reception of a packet matching the WUFF when in PME mode will result in a PME being asserted.

• Perfect DA match of Physical address

Reception of an Ethernet frame whose Destination address matches the device’s MAC address will result in a

PME being asserted.

• Broadcast Packet

Reception of a Broadcast Packet when in PME mode will result in a PME being asserted.

• PHY Link Change

Detection of a PHY link partner when in PME mode will result in a PME being asserted.

In order to facilitate PME mode of operation, the GPIO PME Enable bit in the GPIO PME Flags 0 field must be set and

all remaining GPIO PME Flags 0 and GPIO PME Flags 1 bits must be appropriately configured for pulse or level signal-

ing, buffer type, and GPIO PME WoL selection.

The PME_MODE pin must be driven to the value that determines whether or not the device remains in PME mode of

operation (1) or resumes normal operation (0) when the PME is recognized and cleared by the EC via PME_CLEAR

(RESET_N) assertion.

When in PME mode, RESET_N (PME_CLEAR) or POR will always cause the contents of the EEPROM to be reloaded.

Figure 14-2 flowcharts PME operation while Magic Packet is enabled with a configured EEPROM/OTP in place. The

following conditions hold for OTP/EEPROM Configuration:

•GPIO PME Enable = 1 (enabled)

•GPIO PME Configuration = 0 (PME signaled via level)

•GPIO PME Length = 0 (NA)

•GPIO PME Polarity = 1 (high level signals event)

•GPIO PME Buffer Type = 1 (Push-Pull)

•PME Packet Enable = 1

•PME Perfect DA Enable = 0

•PME WUFF Enable = 0

•Power Method (CFG0_PWR_SEL) = 1 (self powered)

• MAC address for Magic Packet

LAN7850

DS00001993D-page 138  2015 - 2017 Microchip Technology Inc.

Optionally, the Enhanced PHY feature of the Gigabit Ethernet PHY may be enabled during PME operation to further

save power. This is controlled by following Configuration Flags 0 fields:

•Enhanced PHY Sleep Timer (PHY_SLEEP_TIMER)

•Enhanced PHY Wake Timer (PHY_WAKE_TIMER)

•Link Time Out Control (LINK_TIME_OUT_CTRL)

•Enhanced PHY Enable (ACT_PHY_EN)

Note: If utilizing PME mode the system software must appropriately configure the Flag Attributes Register

(FLAG_ATTR).

A POR occurring when PME_MODE = 1 and GPIO PME Enable is set in EEPROM/OTP, results in the

device entering PME Mode.

In this mode the Ethernet interface operates at the negotiated speed.

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 139

LAN7850

FIGURE 14-2: PME OPERATION

LAN7850

DS00001993D-page 140  2015 - 2017 Microchip Technology Inc.

15.0 REGISTER DESCRIPTIONS

This section details the device register descriptions and memory map. The directly addressable memory map is detailed

in Table 15-1. Additional indirectly addressable registers are detailed in the following sub-sections.

Directly Addressable Registers

•Section 15.1, "System Control and Status Registers," on page 141

•Section 15.2, "USB PHY Control and Status Registers," on page 216

Indirectly Addressable Registers

•Section 15.3, "Ethernet PHY Control and Status Registers," on page 223

•Section 15.4, "MDIO Manageable Device (MMD) Control and Status Registers," on page 259

TABLE 15-1: MEMORY MAP

Address Data Space

0x0000-0x0FFF System Control and Status Registers

0x1000-0x11FF Reserved

0x1200-0x15FF USB PHY Control and Status Registers

0x1200-0x1FFF Reserved

Note: For additional information on the device’s OTP memory, refer to Section 11.0, "One Time Programmable

(OTP) Memory," on page 122.

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 141

LAN7850

15.1 System Control and Status Registers

Note: Any access to register offsets 0B0h and above will be STALLed in the Unconfigured state, hence unavail-

able. As a result of this all MAC, FIFO Controller (FCT), and Receive Filtering Engine (RFE) registers will

not be available in the Unconfigured state.

Note: RESER VED address space in the System Control and Status Registers Map must not be written under

any circumstances. Failure to heed this warning may result in untoward operation and unexpected

results.

TABLE 15-2: SYSTEM CONTROL AND STATUS REGISTERS MAP

OFFSET REGISTER NAME

000h Device ID and Revision Register (ID_REV)

004h – 008h Reserved

00Ch Interrupt Status Register (INT_STS)

010h Hardware Configuration Register (HW_CFG)

014h Power Management Control Register (PMT_CTL)

018h General Purpose IO Configuration 0 Register (GPIO_CFG0)

01Ch General Purpose IO Configuration 1 Register (GPIO_CFG1)

020h General Purpose IO Wake Enable and Polarity Register (GPIO_WAKE)

024h Data Port Select Register (DP_SEL)

028h Data Port Command Register (DP_CMD)

02Ch Data Port Address Register (DP_ADDR)

030h Data Port Data Register (DP_DATA)

034h – 03Ch Reserved

040h EEPROM Command Register (E2P_CMD)

044h EEPROM Data Register (E2P_DATA)

048h – 04Fh Reserved

050h BOS Descriptor Attributes Register (BOS_ATTR)

054h Reserved

058h HS Descriptor Attributes Register (HS_ATTR)

05Ch FS Descriptor Attributes Register (FS_ATTR)

060h String Attributes Register 0 (STRNG_ATTR0)

064h String Attributes Register 1 (STRNG_ATTR1)

068h Flag Attributes Register (FLAG_ATTR)

06Ch – 077h Software General Purpose Register x (SW_GPx)

078h – 07Fh Reserved

080h USB Configuration Register 0 (USB_CFG0)

084h USB Configuration Register 1 (USB_CFG1)

088h USB Configuration Register 2 (USB_CFG2)

090h Burst Cap Register (BURST_CAP)

094h Bulk-In Delay Register (BULK_IN_DLY)

098h Interrupt Endpoint Control Register (INT_EP_CTL)

09Ch PIPE Control Register (PIPE_CTL)

0A0h – 0A4h Reserved

0A8h USB Status Register (USB_STATUS)

0ACh Reserved

0B0h Receive Filtering Engine Control Register (RFE_CTL)

LAN7850

DS00001993D-page 142  2015 - 2017 Microchip Technology Inc.

0B4h VLAN Type Register (VLAN_TYPE)

0B8h – 0BFh Reserved

0C0h FIFO Controller RX FIFO Control Register (FCT_RX_CTL)

0C4h FIFO Controller TX FIFO Control Register (FCT_TX_CTL)

0C8h FCT RX FIFO End Register (FCT_RX_FIFO_END)

0CCh FCT TX FIFO End Register (FCT_TX_FIFO_END)

0D0h FCT Flow Control Threshold Register (FCT_FLOW)

0D4h RX Datapath Storage (RX_DP_STOR)

0D8h TX Datapath Storage (TX_DP_STOR)

0DCh – 0FFh Reserved

100h MAC Control Register (MAC_CR)

104h MAC Receive Register (MAC_RX)

108h MAC Transmit Register (MAC_TX)

10Ch Flow Control Register (FLOW)

110h Random Number Seed Value Register (RAND_SEED)

114h Error Status Register (ERR_STS)

118h MAC Receive Address High Register (RX_ADDRH)

11Ch MAC Receive Address Low Register (RX_ADDRL)

120h MII Access Register (MII_ACCESS)

124h MII Data Register (MII_DATA)

128h - 12Fh Reserved

130h EEE TX LPI Request Delay Count Register (EEE_TX_LPI_REQUEST_DELAY_CNT)

134h EEE Time Wait TX System Register (EEE_TW_TX_SYS)

138h EEE TX LPI Automatic Removal Delay Register (EEE_TX_LPI_AUTO_REMOVAL_DELAY)

13Ch - 13Fh Reserved

140h Wakeup Control and Status Register 1 (WUCSR1)

144h Wakeup Source Register (WK_SRC)

148h – 14Fh Reserved

150h - 1CC Wakeup Filter x Configuration Register (WUF_CFGx)

1D0h – 1Fh Reserved

200h – 3FCh Wakeup Filter x Byte Mask Registers (WUF_MASKx)

400h – 504h MAC Address Perfect Filter Registers (ADDR_FILTx)

508h – 5FFh Reserved

600h Wakeup Control and Status Register 2 (WUCSR2)

610h – 61Ch NSx IPv6 Destination Address Register (NSx_IPV6_ADDR_DEST)

620h – 62Ch NSx IPv6 Source Address Register (NSx_IPV6_ADDR_SRC)

630h – 63Ch NSx ICMPv6 Address 0 Register (NSx_ICMPV6_ADDR0)

640h – 64Ch NSx ICMPv6 Address 1 Register (NSx_ICMPV6_ADDR1)

650h – 65Ch NSx IPv6 Destination Address Register (NSx_IPV6_ADDR_DEST)

660h – 66Ch NSx IPv6 Source Address Register (NSx_IPV6_ADDR_SRC)

670h – 67Ch NSx ICMPv6 Address 0 Register (NSx_ICMPV6_ADDR0)

680h – 68Ch NSx ICMPv6 Address 1 Register (NSx_ICMPV6_ADDR1)

690h SYN IPv4 Source Address Register (SYN_IPV4_ADDR_SRC)

694h SYN IPv4 Destination Address Register (SYN_IPV4_ADDR_DEST)

698h SYN IPv4 TCP Ports Register (SYN_IPV4_TCP_PORTS)

69Ch – 6A8h SYN IPv6 Source Address Register (SYN_IPV6_ADDR_SRC)

6ACh – 6B8h SYN IPv6 Destination Address Register (SYN_IPV6_ADDR_DEST)

6BCh SYN IPv6 TCP Ports Register (SYN_IPV6_TCP_PORTS)

TABLE 15-2: SYSTEM CONTROL AND STATUS REGISTERS MAP (CONTINUED)

OFFSET REGISTER NAME

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 143

LAN7850

6C0h ARP Sender Protocol Address Register (ARP_SPA)

6C4h ARP Target Protocol Address Register (ARP_TPA)

6C8h – 6FFh Reserved

700h PHY Device Identifier (PHY_DEV_ID)

704h – FFFh Reserved

TABLE 15-2: SYSTEM CONTROL AND STATUS REGISTERS MAP (CONTINUED)

OFFSET REGISTER NAME

LAN7850

DS00001993D-page 144  2015 - 2017 Microchip Technology Inc.

15.1.1 DEVICE ID AND REVISION REGISTER (ID_REV)

Note 15-1 Default value is dependent on device revision.

15.1.2 INTERRUPT STATUS REGISTER (INT_STS)

Offset: 000h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:16 Chip ID

This read-only field identifies the device model.

RO 7850h

15:0 Chip Revision

This is the revision of the device.

RO Note 15-1

Offset: 00Ch Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:29 RESERVED RO -

28 OTP Write Done Interrupt (OTP_WR_DONE_INT)

OTP write operation has completed.

Note: The source of this interrupt is a level. The interrupt persists until it

is cleared in the OTP.

R/WC 0b

27 RESERVED RO -

26 Energy Efficient Ethernet Start TX Low Power Interrupt

(EEE_START_TX_LPI_INT)

This interrupt is asserted when the transmitter enters low power idle mode,

due to the expiration of the time specified in EEE TX LPI Request Delay

Count Register (EEE_TX_LPI_REQUEST_DELAY_CNT)

This bit is held low if the Energy Efficient Ethernet Enable (EEEEN) bit in the

MAC Control Register (MAC_CR) is low.

Note: The source of this interrupt is a pulse.

R/WC 0b

25 Energy Efficient Ethernet Stop TX Low Power Interrupt

(EEE_STOP_TX_LPI_INT)

This interrupt is asserted when the transmitter exits low power idle mode,

due to the expiration of the time specified in the EEE TX LPI Automatic

Removal Delay Register (EEE_TX_LPI_AUTO_REMOVAL_DELAY).

This bit is held low if the Energy Efficient Ethernet Enable (EEEEN) bit in the

MAC Control Register (MAC_CR) is low.

Note: The source of this interrupt is a pulse.

R/WC 0b

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 145

LAN7850

24 Energy Efficient Ethernet RX Low Power Interrupt (EEE_RX_LPI_INT)

This interrupt is asserted when the receiver enters low power idle mode.

This bit is held low if the Energy Efficient Ethernet Enable (EEEEN) bit in the

MAC Control Register (MAC_CR) is low.

Note: The source of this interrupt is a pulse.

R/WC 0b

23 MAC Reset Time Out (MACRTO_INT)

This interrupt signifies that the 8 ms reset watchdog timer has timed out. This

means that the Ethernet PHY is not supplying RX and TX clocking to the

MAC. After the timer times out, the MAC reset is deasserted asynchronously.

Note: The source of this interrupt is a pulse.

R/WC 0b

22 RX Data FIFO Overflow Interrupt (RDFO_INT)

This interrupt is set when the receive logic attempts to place data into the

RX Data FIFO after it has been completely filled. When set, newly received

data is discarded.

Note: The source of this interrupt is a level.

R/WC 0b

21 Transmitter Error Interrupt (TXE_INT)

This interrupt indicates that the transmitter has encountered an error. Refer

to Section Section 6.2.4, "TX Error Detection", for a description of the

conditions that will cause a TXE.

Note: The source of this interrupt is a level.

R/WC 0b

20 USB Status Interrupt (USB_STS_INT)

This interrupt is issued after a USB status event. This interrupt persists until

the asserted event(s) is cleared in USB Status Register (USB_STATUS).

Note: The source of this interrupt is a level.

R/WC 0b

19 TX Disabled Interrupt (TX_DIS_INT)

This interrupt is issued after the TX FIFO or MAC transmitter has been

successfully disabled.

This interrupt persists when either the FCT TX Disabled bit of the FIFO

Controller TX FIFO Control Register (FCT_TX_CTL) or the Transmitter

Disabled (TXD) bit of the MAC Transmit Register (MAC_TX) is set.

Note: The source of this interrupt is a level.

R/WC 0b

18 RX Disabled Interrupt (RX_DIS_INT)

This interrupt is issued after the RX FIFO or MAC receiver has been

successfully disabled.

This interrupt persists when either the FCT RX Disabled bit of the FIFO

Controller RX FIFO Control Register (FCT_RX_CTL) or the Receiver

Disabled (RXD) bit of the MAC Receiver Register (MAC_RX) is set.

Note: The source of this interrupt is a level.

R/WC 0b

17 PHY Interrupt (PHY_INT)

Indicates an Ethernet PHY Interrupt event.

Note: The source of this interrupt is a level. The interrupt persists until it

is cleared in the PHY.

R/WC 0b

16 Data Port Interrupt (DP_INT)

Indicates that a pending data port operation has been completed.

Note: The source of this interrupt is a pulse.

R/WC 0b

BITS DESCRIPTION TYPE DEFAULT

LAN7850

DS00001993D-page 146  2015 - 2017 Microchip Technology Inc.

Note 15-2 The default depends on the state of the GPIO pin. The clearing of a GPIOx_INT bit also clears the

corresponding GPIO wake event

15.1.3 HARDWARE CONFIGURATION REGISTER (HW_CFG)

15 MAC Error Interrupt (MAC_ERR_INT)

This interrupt is set whenever any error condition tracked in the MAC’s Error

Status Register (ERR_STS) occurs. The application program can determine

the specific error(s) that occurred by examining the Error Status Register

(ERR_STS).

Note: This is a level-triggered interrupt event that remains asserted until

all the error event bits in the Error Status Register (ERR_STS) are

cleared.

R/WC 0b

14:13 RESERVED RO -

12 UTX Frame Pending (UTX_FP)

Indicates the USB TX FIFO has at least one frame pending.

RO 0b

11:0 GPIO [11:0] (GPIOx_INT)

Interrupts are generated from the GPIOs.

Note: The sources for these interrupts are a level.

R/WC Note 15-2

Offset: 010h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:24 RESERVED RO -

23 LED3 Enable (LED3_EN)

When set, the LED3 pin function is enabled.

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W Note 15-6

22 LED2 Enable (LED2_EN)

When set, the LED2 pin function is enabled.

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W Note 15-6

21 LED1 Enable (LED1_EN)

When set, the LED1 pin function is enabled.

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W Note 15-6

20 LED0 Enable (LED0_EN)

When set, the LED0 pin function is enabled.

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W Note 15-6

19:16 RESERVED RO -

15 NetDetach Status (NETDET_STS)

After the driver loads, this bit is checked to determine whether a NetDetach

event occurred.

R/WC Note 15-7

BITS DESCRIPTION TYPE DEFAULT

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 147

LAN7850

14 NetDetach Enable (NETDET_EN)

When this bit is set, the device detaches from the USB bus. This results in

the driver unloading and no further communication with the device. The

device remains detached until PHY link is detected, or a properly configured

GPIO pin is asserted. Occurrence of either event causes the device to attach

to the USB bus, the driver to be loaded, and the NETDET_STS bit to be

asserted.

Note: The CONNECT pin may be enabled to assert in support of this

function.

SC 0b

13 EEPROM Emulation Enable (EEM)

This bit is used to select the source of descriptor information and

configuration flags when no EEPROM is present.

0 = HW generates descriptor based upon CSR defaults.

1 = Use Descriptor RAM and Attributes Registers.

Note: This bit affects operation only when an EEPROM is not present and

OTP is not configured. This bit has no effect when an EEPROM is

present or OTP is configured.

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W 0b

12 Reset Protection (RST_PROTECT)

Setting this bit protects select fields of certain registers from being affected

by resets other than POR.

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W 0b

11 RESERVED RO -

10 CONNECT Pin Buffer Type (CONNECT_BUF)

This bit selects the output buffer type for CONNECT.

0 = Open drain driver

1 = Push-Pull driver

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W Note 15-3

9Connect Pin Enable (CONNECT_EN)

This bit enables the CONNECT pin. When enabled the pin asserts when the

device is attempting to attach to the USB bus.

Note: The CONNECT pin is also functional for NetDetach.

Note: This bit only has meaning when configured for HSIC operation.

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W Note 15-4

8Connect Pin Polarity (CONNECT _POL)

This bit selects the polarity of the CONNECT pin.

0 = Active low

1 = Active high

Note: This bit only has meaning when configured for HSIC operation.

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W Note 15-5

BITS DESCRIPTION TYPE DEFAULT

LAN7850

DS00001993D-page 148  2015 - 2017 Microchip Technology Inc.

Note 15-3 The default value of this bit is determined by the value of the respective GPIO CONNECT Buffer

Type field of GPIO PME Flags 1 contained within the EEPROM, if present. If no EEPROM is present

then default depends on the OTP programmed value. It the OTP is not programmed than 0b is the

7:6 SUSPEND_N Pin Select (SUSPEND_N_SEL)

This bit specifies the modes of operation during which the SUSPEND_N pin

will be asserted.

00b: SUSPEND_N asserted in SUSPEND2.

01b: SUSPEND_N asserted in SUSPEND2, SUSPEND1 and NetDetach.

10b: SUSPEND_N asserted in SUSPEND2, SUSPEND1, SUSPEND0 and

NetDetach.

11b: SUSPEND_N asserted in SUSPEND3, SUSPEND2, SUSPEND1,

SUSPEND0 and NetDetach.

Note: This field is protected by Reset Protection (RST_PROTECT).

Note: The usage of this bit is not gated by the EEPROM Emulation

Enable (EEM) bit or the lack of an EEPROM.

R/W Note 15-8

5SUSPEND_N Pin Polarity (SUSPEND_N _POL)

This bit selects the polarity of the SUSPEND_N pin.

0 = Active low.

1 = Active high

Note: This field is protected by Reset Protection (RST_PROTECT).

Note: The usage of this bit is not gated by the EEPROM Emulation

Enable (EEM) bit or the lack of an EEPROM.

R/W Note 15-9

4Multiple Ethernet Frames per USB Packet (MEF)

This bit enables the USB transmit direction to pack multiple Ethernet frames

per USB packet whenever possible.

0 = Support no more than one Ethernet frame per USB packet

1 = Support packing multiple Ethernet frames per USB packet

R/W 0b

3EEPROM Time-out Control (ETC)

This bit controls the length of time used by the EEPOM controller to detect

a time-out.

0 = Time-out occurs if no response received from EEPROM after 30 ms.

1 = Time-out occurs if no response received from EEPROM after 1.28 us.

Note: When a timeout occurs it is indicated via EPC Time-out (EPC_TO)

in EEPROM Command Register (E2P_CMD).

R/W 0b

2RESERVED RO -

1Soft Lite Reset (LRST)

Writing 1 generates the lite software reset of the device.

A lite reset will not affect the USB controller and will not cause the USB PHY

to disconnect. Additionally, the contents of the EEPROM will not be reloaded.

This bit clears after the reset sequence has completed.

SC 0b

0Soft Reset (SRST)

Writing 1 generates a software initiated reset of the device.

A software reset will result in the contents of the EEPROM being reloaded.

While the reset sequence is in progress, the USB PHY will be disconnected.

After the device has been re-initialized, it will take the PHY out of the

disconnect state and be visible to the Host.

SC 0b

BITS DESCRIPTION TYPE DEFAULT

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 149

LAN7850

default. A USB Reset or Lite Reset (LRST) will cause this field to be restored to the image value last

loaded from EEPROM, OTP, or to be set to 0b if neither is available.

Note 15-4 The default value of this bit is determined by the value of the respective GPIO CONNECT Enable

field of GPIO PME Flags 0 contained within the EEPROM, if present. If no EEPROM is present then

default depends on the OTP programmed value. It the OTP is not programmed then 0b is the default.

A USB Reset or Lite Reset (LRST) will cause this field to be restored to the image value last loaded

from EEPROM, OTP, or to be set to 0b if neither is available.

Note 15-5 The default value of this bit is determined by the value of the respective GPIO CONNECT Polarity

field of GPIO PME Flags 0 contained within the EEPROM, if present. If no EEPROM is present then

default depends on the OTP programmed value. It the OTP is not programmed then 0b is the default.

A USB Reset or Lite Reset (LRST) will cause this field to be restored to the image value last loaded

from EEPROM, OTP, or to be set to 0b if neither is available.

Note 15-6 The default value of this bit is determined by the value of the respective LED_EN field of LED

Configuration 0 contained within the EEPROM, if present. If no EEPROM is present then default

depends on the OTP programmed value. It the OTP is not programmed then 0b is the default. A USB

Reset or Lite Reset (LRST) will cause this field to be restored to the image value last loaded from

EEPROM, OTP, or to be set to 0b if neither is available.

Note 15-7 The default value of this bit depends on whether a NetDetach event occurred. If set, the event

occurred.

Note 15-8 The default value of this bit is determined by the value of the SUSPEND_N Select

(CFG0_SUSPEND_N_SEL) bit of Configuration Flags 0 contained within the EEPROM, if present. If

no EEPROM is present then default depends on the OTP programmed value. It the OTP is not

programmed then 00b is the default. A USB Reset or Lite Reset (LRST) will cause this field to be

restored to the image value last loaded from EEPROM, OTP, or to be set to 00b if neither is available.

Note 15-9 The default value of this field is determined by the value of the SUSPEND_N Polarity

(CFG0_SUSPEND_N_POL) bit of Configuration Flags 0 contained within the EEPROM, if present. If

no EEPROM is present then default depends on the OTP programmed value. It the OTP is not

programmed then 0b is the default. A USB Reset or Light Reset (LRST) shall cause this field to be

restored to the image value last loaded from EEPROM, OTP, or to be set to 0b if neither is available.

LAN7850

DS00001993D-page 150  2015 - 2017 Microchip Technology Inc.

15.1.4 POWER MANAGEMENT CONTROL REGISTER (PMT_CTL)

This register controls the power management features.

Offset: 014h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:16 RESERVED RO -

15 Disable Wait Analog Voltage Reference Stable (DIS_WAIT_ANA_REF)

This bit disables waiting for the analog voltage reference to stabilize when

the Ethernet PHY is placed in reset to maximize power savings.

When this bit is set the analog reference is not disabled when the PHY is

reset. When the reference is disabled a delay in the order of 100 ms is

required for the PHY to stabilize.

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W 0b

14 Crystal Suspend Disable (XTAL_SUSP_DIS)

0 - Normal Crystal driver operation

1 - Crystal is never suspended

Note: When asserted, this bit prevents the crystal oscillator from being

disabled in SUSPEND2 and UNPOWERED modes.

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W Note 15-10

13 EEE WAKE-UP Enable (EEE_WAKEUP_EN)

Enables EEE WAKE-UP Status (EEE_WUPS) as a wakeup event.

This bit is automatically cleared at the completion of a resume sequence if

Resume Clears Remote Wakeup Enables (RES_CLR_WKP_EN) is set.

R/W 0b

12 EEE WAKE-UP Status (EEE_WUPS)

This field indicates if the cause of the current wake-up event is due to EEE.

It is used along with WAKE-UP Status (WUPS). See the WUPS field for the

encoding.

This bit will set regardless of the value in EEE WAKE-UP Enable

(EEE_WAKEUP_EN).

If the Resume Clears Remote Wakeup Status (RES_CLR_WKP_STS) bit is

set, this bit will clear upon completion of a resume. See the

RES_CLR_WKP_STS bit for further details.

Note: It is not valid to simultaneously clear the EEE_WUPS bit and

change the contents of the Suspend Mode (SUSPEND_MODE)

field.

R/WC 0b

11 MAC Soft Reset (MAC_SRST)

The MAC RX/TX clock domains will be held in reset when this bit is high.

This bit must then be cleared to resume normal operation. MAC RX/TX

resets will be deasserted only if RX/TX clocks are running.

R/W 0b

10 RESERVED RO -

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 151

LAN7850

9Resume Clears Remote Wakeup Status (RES_CLR_WKP_STS)

When set, the following status signals in WUCSR1 and WUCSR2 will clear

upon the completion of a resume sequence:

WUCSR1:

RFE Wakeup Frame Received (RFE_WAKE_FR)

Perfect DA Frame Received (PFDA_FR)

Remote Wakeup Frame Received (WUFR)

Magic Packet Received (MPR)

Broadcast Frame Received (BCAST_FR)

Energy Efficient Ethernet TX Wake (EEE_TX_WAKE)

Energy Efficient Ethernet RX Wake (EEE_RX_WAKE)

WUCSR2:

IPv6 TCP SYN Packet Received (IPV6_TCPSYN_RCD)

IPv4 TCP SYN Packet Received (IPV4_TCPSYN_RCD)

When set, this bit also affects the WUPS field. WUPS[1] and EEE_WUPS

will clear upon completion of a resume event.

Only resume sequences initiated by the above listed wake events wakeup

frame or magic packet are affected by RES_CLR_WKP_STS. Resumes

initiated by the host do not clear the wakeup statuses.

When cleared, the wakeup status signals are not cleared after a resume.

R/W 0b

8Resume Clears Remote Wakeup Enables (RES_CLR_WKP_EN)

When asserted, all wakeup enable bits in WUCSR and WUCSR2 are cleared

after a resume sequence, initiated from a remote wakeup, completes.

Resumes initiated by the host do not clear the wakeup enables.

R/W 1b

7Device Ready (READY)

The READY bit is used to indicate when the device is ready for normal

operation.

The READY bit remains deasserted for the following reasons:

Waiting for the Gigabit Ethernet PHY reset sequence to complete and the

PHY to become operational. This could take over 125 ms depending on

how the device is configured.

Waiting for content to be loaded from the EEPROM or OTP. This would

only be visible to the application for the case of a USB Reset where the

Ethernet MAC address is reloaded.

See Table 15-3, "Device Ready Bit Behavior" for further details.

RO 0b

6:5 Suspend Mode (SUSPEND_MODE)

Indicates which suspend power state to use after the Host suspends the

device.

If the device is unconfigured, it transitions to the NORMAL Unconfigured

state and this register will reset to the value 10b.

SUSPEND_MODE encoding:

00 = SUSPEND0

01 = SUSPEND1

10 = SUSPEND2

11 = SUSPEND3

Note: It is not valid to select any suspend variant besides SUSPEND2

when in the NORMAL Unconfigured state.

Note: SUSPEND0 and SUSPEND1 are functionally identical in this

device. They are maintained as separate selectable states for

nomenclature compatibility with legacy devices.

R/W 10b

BITS DESCRIPTION TYPE DEFAULT

LAN7850

DS00001993D-page 152  2015 - 2017 Microchip Technology Inc.

4PHY Reset (PHY_RST)

Writing a '1' to this bit resets the Ethernet PHY. The internal logic

automatically holds the PHY reset for a minimum of 4 ms. When the PHY is

released from reset, this bit is automatically cleared. All writes to this bit are

ignored while this bit is high.

The Device Ready (READY) bit shall clear upon setting this bit. When the

PHY is operational Device Ready (READY) bit shall assert.

Note: This reset may be extended to 128 ms depending on the state of

Disable Wait Analog Voltage Reference Stable

(DIS_WAIT_ANA_REF).

Note: This bit should be set after resuming from SUSPEND2.

SC 0b

3Wake-On-LAN Enable (WOL_EN)

Enables WOL as a wakeup event which includes the following. See Section

13.4.1, "Detecting Wakeup Events" for details on which wake events are

affected by this bit.

This bit is automatically cleared at the completion of a resume sequence if

Resume Clears Remote Wakeup Enables (RES_CLR_WKP_EN) is set.

R/W 0b

2PHY Interrupt Enable (PHY_WAKE_EN)

Ethernet PHY Interrupt as a wakeup event. See Section 13.4.1, "Detecting

Wakeup Events" for further details.

This bit is automatically cleared at the completion of a resume sequence if

Resume Clears Remote Wakeup Enables (RES_CLR_WKP_EN) is set.

R/W 0b

BITS DESCRIPTION TYPE DEFAULT

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 153

LAN7850

Note 15-10 The default value of this bit is determined by the Crystal Suspend Disable (XTAL_SUSP_DIS) bit of

Configuration Flags 1 contained within the EEPROM, if present. If no EEPROM is present the default

depends on the OTP programmed value. It the OTP is not programmed than 1b is the default. A USB

Reset or Lite Reset (LRST) shall cause this field to be restored to the image value last loaded from

EEPROM, OTP, or to be set to 1b if neither is available.

1:0 WAKE-UP Status (WUPS)

This field, along with EEE WAKE-UP Status (EEE_WUPS), indicates the

cause of the current wake-up event. WUPS bits are cleared by writing a ‘1’

to the appropriate bit. The encoding of these bits is as follows:

More than one bit may be set indicating that multiple events occurred.

The WUPS field will not be set unless the corresponding event is enabled

prior to entering the reduced power state.

These bits will set regardless of the values in Wake-On-LAN Enable

(WOL_EN) and PHY Interrupt Enable (PHY_WAKE_EN).

If Resume Clears Remote Wakeup Status (RES_CLR_WKP_STS) is set,

WUPS[1] will clear upon completion of a resume. See the

RES_CLR_WKP_STS bit for further details.

Note: It is not valid to simultaneously clear the WUPS bits and change

the contents of the Suspend Mode (SUSPEND_MODE) field.

R/WC 00b

BITS DESCRIPTION TYPE DEFAULT

EEE_WUPS WUPS[1:0] EVENT

0 00 No wake-up event detected

X X1 • Ethernet PHY Wake Event

X 1X • Wake-On-LAN

• TCP SYN

• “Good Frame”

• Broadcast Frame

• Multicast Frame

• Perfect DA Match

1 XX EEE Receive Wake (EEE_RX_WAKE))

(SUSPEND0 & SUSPEND3) / EEE

Transmit Wake (EEE_TX_WAKE)

(SUSPEND3)

LAN7850

DS00001993D-page 154  2015 - 2017 Microchip Technology Inc.

TABLE 15-3: DEVICE READY BIT BEHAVIOR

Event Internal PHY External PHY

Transition into

NORMAL-Unconfigured

Ready bit remains cleared since

Ethernet PHY is reset to minimize

power consumption.

Ready bit is set after EEPROM/

OTP loading is completed.

EEPROM emulation does not

introduce a comparable delay.

This should only be visible to the

application after a USB Reset in

which and EEPROM/OTP load is

required to retrieve the MAC

address.

Transition from

NORMAL-Unconfigured ->

NORMAL-Configured

Ready bit asserts after Ethernet

PHY reset is deasserted and PHY

becomes operational.

Ready bit is set.

There is no state change in

READY bit since it is set in the

NORMAL-Unconfigured state.

Transition from

SUSPEND2 ->

NORMAL-Configured

Ethernet PHY is held in reset while

SUSPEND2 to save power. After

PHY reset is deasserted after mov-

ing to the Normal-Configured the

READY bit asserts.

The External Ethernet PHY is not

reset from moving to SUSPEND2.

Ready bit does not clear when

entering SUSPEND2.

PHY Reset (PHY_RST) Ready bit remains cleared until

PHY reset deasserts.

Ready bit remains cleared until

PHY reset deasserts.

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 155

LAN7850

15.1.5 GENERAL PURPOSE IO CONFIGURATION 0 REGISTER (GPIO_CFG0)

This register configures the external GPIO[3:0] pins.

In order for a GPIO to function as a wake event or interrupt source, it must be configured as an input. GPIO pins used

to generate wake events must also be enabled by General Purpose IO Wake Enable and Polarity Register (GPI-

O_WAKE).

Note 15-11 The default value of this field is determined by the value of the GPIO 0-11 Enable contained within

the EEPROM, if present. If no EEPROM is present then the value programmed in OTP is used. If

OTP is not configured then 0xF is the default. A USB Reset or Lite Reset (LRST) will cause this field

to be restored to the image value last loaded from EEPROM, or OTP, or to be set to 0xF if neither

is present.

Address: 018h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:16 RESERVED RO -

15:12 GPIO Enable (GPIOEN)

When clear, the pin functions as a GPIO.

GPIOEN0 – bit 12

GPIOEN1 – bit 13

GPIOEN2 – bit 14

GPIOEN3 – bit 15

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W Note 15-11

11:8 GPIO Buffer Type (GPIOBUF)

When set, the output buffer for the corresponding GPIO signal is configured

as a push/pull driver. When cleared, the corresponding GPIO signal is

configured as an open-drain driver. Bits are assigned as follows:

GPIOBUF0 – bit 8

GPIOBUF1 – bit 9

GPIOBUF2 – bit 10

GPIOBUF3 – bit 11

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W Note 15-12

7:4 GPIO Direction (GPIODIR)

When set, enables the corresponding GPIO as an output. When cleared the

GPIO is enabled as an input. Bits are assigned as follows:

GPIODIR0 – bit 4

GPIODIR1 – bit 5

GPIODIR2 – bit 6

GPIODIR3 – bit 7

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W Note 15-13

3:0 GPIO Data (GPIOD)

When enabled as an output, the value written is reflected on GPIOn. When

read, GPIOn reflects the current state of the corresponding GPIO pin. Bits

are assigned as follows:

GPIOD0 – bit 0

GPIOD1 – bit 1

GPIOD2 – bit 2

GPIOD3 – bit 3

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W Note 15-14

LAN7850

DS00001993D-page 156  2015 - 2017 Microchip Technology Inc.

Note 15-12 The default value of this field is determined by the value of the GPIO 0-11 Buffer contained within

the EEPROM, if present. If no EEPROM is present then the value programmed in OTP is used. If

OTP is not configured then 0x0 is the default. A USB Reset or Lite Reset (LRST) will cause this field

to be restored to the image value last loaded from EEPROM, or OTP, or to be set to 0x0 if neither

is present.

Note 15-13 The default value of this field is determined by the value of the GPIO 0-11 Direction contained within

the EEPROM, if present. If no EEPROM is present then the value programmed in OTP is used. If

OTP is not configured then 0x0 is the default. A USB Reset or Lite Reset (LRST) will cause this field

to be restored to the image value last loaded from EEPROM, or OTP, or to be set to 0x0 if neither

is present.

Note 15-14 The default value of this field is determined by the value of the GPIO 0-11 Data contained within the

EEPROM, if present. If no EEPROM is present then the value programmed in OTP is used. If OTP

is not configured then 0x0 is the default. A USB Reset or Lite Reset (LRST) will cause this field to

be restored to the image value last loaded from EEPROM, or OTP, or to be set to 0x0 if neither is

present. In the event that the GPIO is configured as an input the default state is unknown.

15.1.6 GENERAL PURPOSE IO CONFIGURATION 1 REGISTER (GPIO_CFG1)

This register configures the external GPIO[4:11] pins.

In order for a GPIO to function as a wake event or interrupt source, it must be configured as an input. GPIOs used as

wake events must also be enabled by General Purpose IO Wake Enable and Polarity Register (GPIO_WAKE).

Address: 01Ch Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:24 GPIO Enable (GPIOEN)

When clear, the pin functions as a GPIO.

GPIOEN4 - bit 24

GPIOEN5 - bit 25

GPIOEN6 - bit 26

GPIOEN7 - bit 27

GPIOEN8 - bit 28

GPIOEN9 - bit 29

GPIOEN10 - bit 30

GPIOEN11 - bit 31

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W Note 15-15

23:16 GPIO Buffer Type (GPIOBUF)

When set, the output buffer for the corresponding GPIO signal is configured

as a push/pull driver. When cleared, the corresponding GPIO signal is

configured as an open-drain driver.

GPIOBUF4 - bit 16

GPIOBUF5 - bit 17

GPIOBUF6 - bit 18

GPIOBUF7 - bit 19

GPIOBUF8 - bit 20

GPIOBUF9 - bit 21

GPIOBUF10 - bit 22

GPIOBUF11 - bit 23

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W Note 15-12

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 157

LAN7850

Note 15-15 The default value of this field is determined by the value of the GPIO 0-11 Enable contained within

the EEPROM, if present. If no EEPROM is present then the value programmed in OTP is used. If

OTP is not configured then 0xFF is the default. A USB Reset or Lite Reset (LRST) will cause this

field to be restored to the image value last loaded from EEPROM, or OTP, or to be set to 0xFF if

neither is present.

15:8 GPIO Direction (GPIODIR)

When set, enables the corresponding GPIO as output. When cleared, the

GPIO is enabled as an input.

GPIODIR4 - bit 8

GPIODIR5 - bit 9

GPIODIR6 - bit 10

GPIODIR7 - bit 11

GPIODIR8 - bit 12

GPIODIR9 - bit 13

GPIODIR10 - bit 14

GPIODIR11 - bit 15

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W Note 15-13

7:0 GPIO Data (GPIOD)

When enabled as an output, the value written is reflected on GPIOn. When

read, GPIOn reflects the current state of the corresponding GPIO pin.

GPIOD4 - bit 0

GPIOD5 - bit 1

GPIOD6 - bit 2

GPIOD7 - bit 3

GPIOD8 - bit 4

GPIOD9 - bit 5

GPIOD10 - bit 6

GPIOD11 - bit 7

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W Note 15-14

BITS DESCRIPTION TYPE DEFAULT

LAN7850

DS00001993D-page 158  2015 - 2017 Microchip Technology Inc.

15.1.7 GENERAL PURPOSE IO WAKE ENABLE AND POLARITY REGISTER (GPIO_WAKE)

This register enables the GPIOs to function as wake events for the device when asserted. It also allows the polarity used

for a wake event/interrupt to be configured.

Note: GPIOs must not cause a wake event to the device when not configured as a GPIO.

Note 15-16 The default value of this field is loaded from the associated bytes of the EEPROM. The high order,

unused bits, of the EEPROM are ignored. If no EEPROM is present then default depends on the

OTP programmed value. It the OTP is not programmed than 0h is the default. A USB Reset or Lite

Reset (LRST) will cause this field to be restored to the image value last loaded from EEPROM, OTP,

or to be set to 0h if neither is available.

Address: 020h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:28 RESERVED RO -

27:16 GPIO Polarity 0-11 (GPIOPOL[11:0])

0 = Wakeup/interrupt is triggered when GPIO is driven low

1 = Wakeup/interrupt is triggered when GPIO is driven high

GPIOPOL0 - bit 16

GPIOPOL1 - bit 17

GPIOPOL2 - bit 18

GPIOPOL3 - bit 19

GPIOPOL4 - bit 20

GPIOPOL5 - bit 21

GPIOPOL6 - bit 22

GPIOPOL7 - bit 23

GPIOPOL8 - bit 24

GPIOPOL9 - bit 25

GPIOPOL10 - bit 26

GPIOPOL11 - bit 27

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W Note 15-16

15:12 RESERVED RO -

11:0 GPIO Wake 0-11 (GPIOWK[11:0])

0 = The GPIO can not wake up the device.

1 = The GPIO can trigger a wake up event.

GPIOWK0 - bit 0

GPIOWK1 - bit 1

GPIOWK2 - bit 2

GPIOWK3 - bit 3

GPIOWK4 - bit 4

GPIOWK5 - bit 5

GPIOWK6 - bit 6

GPIOWK7 - bit 7

GPIOWK8 - bit 8

GPIOWK9 - bit 9

GPIOWK10 - bit 10

GPIOWK11 - bit 11

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W Note 15-16

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 159

LAN7850

15.1.8 DATA PORT SELECT REGISTER (DP_SEL)

15.1.9 DATA PORT COMMAND REGISTER (DP_CMD)

This register commences the data port access. Writing a one to this register will enable a write access, while writing a

zero will do a read access.

The address and data registers need to be configured appropriately for the desired read or write operation before

accessing this register.

Offset: 024h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31 Data Port Ready (DPRDY)

The Data Port Ready bit indicates when the data port RAM access has

completed. In the case of a read operation, this bit indicates when the read

data has been stored in the DP_DATA register

1 = Data Port is ready.

0 = Data Port is busy processing a transaction.

RO 1b

30:4 RESERVED RO -

3:0 Select (SEL)

Selects which RAM to access.

0000 = URX Buffer RAM (Do not access at run time)

0001 = RFE VLAN and DA Hash Table (VHF RAM)

0010 = LSO Header RAM (Do not access at run time)

0011 = FCT RX RAM (Do not access at run time)

0100 = FCT TX RAM (Do not access at run time)

0101 = Descriptor RAM (Do not access at run time)

0110 = RESERVED

0111 = UTX Buffer RAM (Do not access at run time)

1000 = RESERVED

1001 = RESERVED

1010 = RESERVED

1011 = RESERVED

1100 = RESERVED

1101 = RESERVED

1110 = RESERVED

1111 = RESERVED

R/W 0000b

Offset: 028h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:1 RESERVED RO -

0Data Port Write. Selects operation. Writing to this bit initiates the dataport

access.

1 = Write operation

0 = Read operation

R/W 0b

LAN7850

DS00001993D-page 160  2015 - 2017 Microchip Technology Inc.

15.1.10 DATA PORT ADDRESS REGISTER (DP_ADDR)

Indicates the address to be used for the data port access.

15.1.11 DATA PORT DATA REGISTER (DP_DATA)

The Data Port Data register holds the write data for a write access and the resultant read data for a read access.

Before reading this register for the result of a read operation, the Data Port Ready bit should be checked. The Data Port

Ready bit must indicate the data port is ready. Otherwise the read operation is still in progress.

15.1.12 EEPROM COMMAND REGISTER (E2P_CMD)

This register is used to control the read and write operations on the Serial EEPROM.

Offset: 02Ch Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:14 RESERVED RO -

13:0 Data Port Address[13:0] R/W 0000h

Offset: 030h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:0 Data Port Data (DATA_PORT_DATA) R/W 0000_0000h

Offset: 040h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31 EPC Busy (EPC_BSY)

When a “1” is written into this bit, the operation specified in the EPC

Command field is performed at the specified EEPROM address. This bit will

remain set until the operation is at which time it will clear. In the case of a

read, this means that the Host can read valid data from the EEPROM Data

be modified until this bit is cleared. In the case where a write is attempted

and an EEPROM is not present, the EPC Busy remains busy until the EPC

Time-out occurs. At that time, the busy bit is cleared.

SC 0b

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 161

LAN7850

30:28 EPC Command (EPC_CMD)

This field is used to issue commands to the EEPROM Controller. The EPC

will execute commands when the EPC Busy bit is set. A new command must

not be issued until the previous command completes. This field is encoded

as follows:

000 = READ

001 = EWDS

010 = EWEN

011 = WRITE

100 = WRAL

101 = ERASE

110 = ERAL

111 = RELOAD

READ (Read Location): This command will cause a read of the EEPROM

location pointed to by EPC Address (EPC_ADDR). The result of the read is

available in the E2P_DATA register.

EWDS (Erase/Write Disable): After issued, the EEPROM will ignore erase

and write commands. To re-enable erase/write operations, issue the EWEN

command.

EWEN (Erase/Write Enable): Enables the EEPROM for erase and write

operations. The EEPROM will allow erase and write operations until the

Erase/Write Disable command is sent, or until power is cycled.

Note: The EEPROM device will power-up in the erase/write-disabled

state. Any erase or write operations will fail until an Erase/Write

Enable command is issued.

WRITE (Write Location): If erase/write operations are enabled in the

EEPROM, this command will cause the contents of the E2P_DATA register

to be written to the EEPROM location selected by the EPC Address

(EPC_ADDR) field.

WRAL (Write All): If erase/write operations are enabled in the EEPROM,

this command will cause the contents of the E2P_DATA register to be written

to every EEPROM memory location.

ERASE (Erase Location): If erase/write operations are enabled in the

EEPROM, this command will erase the location selected by the EPC

Address (EPC_ADDR) field.

ERAL (Erase All): If erase/write operations are enabled in the EEPROM,

this command will initiate a bulk erase of the entire EEPROM.

RELOAD (Data Reload): Instructs the EEPROM Controller to reload the

data from the EEPROM. If a value of A5h is not found in the first address of

the EEPROM, the EEPROM is assumed to be un-programmed and the

Reload operation will fail. The EPC Data Loaded (EPC_DL) bit indicates a

successful load of the data.

Note: A failed reload operation will result in no change to descriptor

information or register contents. These items will not be set to

default values as a result of the reload failure.

R/W 000b

27:11 RESERVED RO -

BITS DESCRIPTION TYPE DEFAULT

LAN7850

DS00001993D-page 162  2015 - 2017 Microchip Technology Inc.

15.1.13 EEPROM DATA REGISTER (E2P_DATA)

This register is used in conjunction with the E2P_CMD register to perform read and write operations to the Serial

EEPROM.

10 EPC Time-out (EPC_TO)

If an EEPROM operation is performed, and there is no response from the

EEPROM within 30mS, the EEPROM Controller will time-out and return to

its idle state. This bit is set when a time-out occurs, indicating that the last

operation was unsuccessful.

Note: If the EEDI pin is pulled-high (default if left unconnected), EPC

commands will not time out if the EEPROM device is missing. In

this case, the EPC Busy bit will be cleared as soon as the

command sequence is complete. It should also be noted that the

ERASE, ERAL, WRITE and WRAL commands are the only EPC

commands that will time-out if an EEPROM device is not present

and the EEDI signal is pulled low.

R/WC 0b

9EPC Data Loaded (EPC_DL)

When set, this bit indicates that a valid EEPROM was found, and that the

MAC Address and default register programming has completed normally.

This bit is set after a successful load of the data after power-up, or after a

RELOAD command has completed.

R/WC 0b

8:0 EPC Address (EPC_ADDR)

The 9-bit value in this field is used by the EEPROM Controller to address a

specific memory location in the Serial EEPROM. This is a BYTE aligned

address.

R/W 00h

Offset: 044h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:8 RESERVED RO -

7:0 EEPROM Data (EPC_DATA)

Value read from or written to the EEPROM.

R/W -

BITS DESCRIPTION TYPE DEFAULT

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 163

LAN7850

15.1.14 BOS DESCRIPTOR ATTRIBUTES REGISTER (BOS_ATTR)

This register sets the length values for BOS Block contents that have been loaded into Descriptor RAM via the Data

Port registers. The Descriptor RAM images may be used, in conjunction with this register, to facilitate customized oper-

ation when no EEPROM is present and OTP is not configured.

Note: If the block does not exist in Descriptor RAM, its size value must be written as 00h.

Note: This register only affects system operation when an EEPROM is not present, OTP is not configured and the

EEPROM Emulation Enable (EEM) bit indicates Descriptor RAM and the Attributes Registers are to be used

for descriptor processing.

Note: Writing to this register when an EEPROM is present or OTP is configured is prohibited and shall result in

untoward operation and unexpected results.

Note: This register is protected by Reset Protection (RST_PROTECT).

Note 15-17 If this field is not 0, the block must include Binary Object Store (BOS) Descriptor; and may include

USB 2.0 Extension Descriptor, and Container ID Descriptor.

Note 15-18 The default value of this field is determined by the value of the Binary Object Store (BOS) Block

Length (Bytes) contained within the EEPROM, if present. If no EEPROM is present then default

depends on the OTP programmed value. It the OTP is not programmed then 00h is the default. A

USB Reset or Lite Reset (LRST) will cause this field to be restored to the image value last loaded

from EEPROM, OTP, or to be set to 00h if neither is available.

Offset: 050h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:8 RESERVED RO -

7:0 BOS Block Size (BOS_BLOCK_SIZE)

Note 15-17

R/W Note 15-18

LAN7850

DS00001993D-page 164  2015 - 2017 Microchip Technology Inc.

15.1.15 HS DESCRIPTOR ATTRIBUTES REGISTER (HS_ATTR)

This register sets the length values for HS descriptors that have been loaded into Descriptor RAM via the Data Port

registers. The HS Polling interval is also defined by a field within this register. The Descriptor RAM images may be used,

in conjunction with this register, to facilitate customized operation when no EEPROM is present or OTP is not config-

ured.

Note: If a descriptor does not exist in Descriptor RAM, its size value must be written as 00h.

Note: This register only affects system operation when an EEPROM is not present, OTP is not configured, and

the EEPROM Emulation Enable (EEM) bit indicates Descriptor RAM and the Attributes Registers are to be

used for descriptor processing.

Note: Writing to this register when an EEPROM is present or OTP is configured is prohibited and will result in

untoward operation and unexpected results.

Note: This register is protected by Reset Protection (RST_PROTECT).

Note 15-19 The default value of this field is determined by the value of the High-Speed Polling Interval for

Interrupt Endpoint contained within the EEPROM, if present. If no EEPROM is present then the vale

programmed in OTP is used. If OTP is not configured then 04h is the default. A USB Reset or Lite

Reset (LRST) will cause this field to be restored to the image value last loaded from EEPROM, or

OTP, or to be set to 04h if neither is present.

Note 15-20 The only legal values are 0 and 12h. Writing any other values will result in untoward behavior and

unexpected results.

Note 15-21 The default value of this field is determined by the value of the High-Speed Device Descriptor (bytes)

contained within the EEPROM, if present. If no EEPROM is present then the vale programmed in

OTP is used. If OTP is not configured then 00h is the default. A USB Reset or Lite Reset (LRST)

will cause this field to be restored to the image value last loaded from EEPROM, or OTP, or to be

set to 00h if neither is present.

Note 15-22 The default value of this field is determined by the value of the High-Speed Configuration and

Interface Descriptor Length (bytes) contained within the EEPROM, if present. If no EEPROM is

present then the vale programmed in OTP is used. If OTP is not configured then 00h is the default.

A USB Reset or Lite Reset (LRST) will cause this field to be restored to the image value last loaded

from EEPROM, or OTP, or to be set to 00h if neither is present.

Address: 058h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:24 RESERVED RO -

23:16 HS Polling Interval (HS_POLL_INT) R/W Note 15-19

15:8 HS Device Descriptor Size (HS_DEV_DESC_SIZE) Note 15-20 R/W Note 15-21

7:0 HS Configuration Descriptor Size (HS_CFG_DESC_SIZE) Note 15-20 R/W Note 15-22

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 165

LAN7850

15.1.16 FS DESCRIPTOR ATTRIBUTES REGISTER (FS_ATTR)

This register sets the length values for FS descriptors that have been loaded into Descriptor RAM via the Data Port reg-

isters. The FS Polling interval is also defined by a field within this register. The Descriptor RAM images may be used,

in conjunction with this register, to facilitate customized operation when no EEPROM is present or OTP is not config-

ured.

Note: If a descriptor does not exist in Descriptor RAM, its size value must be written as 00h.

Note: This register only affects system operation when an EEPROM is not present, OTP is not configured, and

the EEPROM Emulation Enable (EEM) bit indicates Descriptor RAM and the Attributes Registers are to be

used for descriptor processing.

Note: Writing to this register when an EEPROM is present or OTP is configured is prohibited and will result in

untoward operation and unexpected results.

Note: This register is protected by Reset Protection (RST_PROTECT).

Note 15-23 The default value of this field is determined by the value of the Full-Speed Polling Interval for Interrupt

Endpoint contained within the EEPROM, if present. If no EEPROM is present then the value

programmed in OTP is used. If OTP is not configured then 01h is the default. A USB Reset or Lite

Reset (LRST) will cause this field to be restored to the image value last loaded from EEPROM, or

OTP, or to be set to 01h if neither is present.

Note 15-24 The only legal values are 0 and 12h. Writing any other values will result in untoward behavior and

unexpected results.

Note 15-25 The default value of this field is determined by the value of the Full-Speed Device Descriptor Length

(bytes) contained within the EEPROM, if present. If no EEPROM is present then the value

programmed in OTP is used. If OTP is not configured then 00h is the default. A USB Reset or Lite

Reset (LRST) will cause this field to be restored to the image value last loaded from EEPROM, or

OTP, or to be set to 00h if neither is present.

Note 15-26 The default value of this field is determined by the value of the Full-Speed Configuration and Interface

Descriptor Length (bytes) contained within the EEPROM, if present. If no EEPROM is present then

the vale programmed in OTP is used. If OTP is not configured then 00h is the default. A USB Reset

or Lite Reset (LRST) will cause this field to be restored to the image value last loaded from EEPROM,

or OTP, or to be set to 00h if neither is present.

Address: 05Ch Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:24 RESERVED RO -

23:16 FS Polling Interval (FS_POLL_INT) R/W Note 15-23

15:8 FS Device Descriptor Size (FS_DEV_DESC_SIZE) Note 15-24 R/W Note 15-25

7:0 FS Configuration Descriptor Size (FS_CFG_DESC_SIZE) Note 15-24 R/W Note 15-26

LAN7850

DS00001993D-page 166  2015 - 2017 Microchip Technology Inc.

15.1.17 STRING ATTRIBUTES REGISTER 0 (STRNG_ATTR0)

This register sets the length values for the named string descriptors that have been loaded into Descriptor RAM via the

Data Port registers. The Descriptor RAM images may be used, in conjunction with this register, to facilitate customized

operation when no EEPROM is present or OTP is not configured.

Note: If a descriptor does not exist in Descriptor RAM, its size value must be written as 00h.

Note: This register only affects system operation when an EEPROM is not present, OTP is not configured, and

the EEPROM Emulation Enable (EEM) bit indicates Descriptor RAM and the Attributes Registers are to be

used for descriptor processing.

Note: Writing to this register when an EEPROM is present or OTP is configured is prohibited and will result in

untoward operation and unexpected results.

Note: This register is protected by Reset Protection (RST_PROTECT).

Note 15-27 The default value of this field is determined by the value of the Configuration String Descriptor Length

(bytes) contained within the EEPROM, if present. If no EEPROM is present then the value

programmed in OTP is used. If OTP is not configured then 00h is the default. A USB Reset or Lite

Reset (LRST) will cause this field to be restored to the image value last loaded from EEPROM, or

OTP, or to be set to 00h if neither is present.

Note 15-28 The default value of this field is determined by the value of the Serial Number String Descriptor

Length (bytes) contained within the EEPROM, if present. If no EEPROM is present then the value

programmed in OTP is used. If OTP is not configured then 00h is the default. A USB Reset or Lite

Reset (LRST) will cause this field to be restored to the image value last loaded from EEPROM, or

OTP, or to be set to 00h if neither is present.

Note 15-29 The default value of this field is determined by the value of the Product Name String Descriptor

Length (bytes) contained within the EEPROM, if present. If no EEPROM is present then the value

programmed in OTP is used. If OTP is not configured then 00h is the default. A USB Reset or Lite

Reset (LRST) will cause this field to be restored to the image value last loaded from EEPROM, or

OTP, or to be set to 00h if neither is present.

Note 15-30 The default value of this field is determined by the value of the Manufacturer ID String Descriptor

Length (bytes) contained within the EEPROM, if present. If no EEPROM is present then the value

programmed in OTP is used. If OTP is not configured then 00h is the default. A USB Reset or Lite

Reset (LRST) will cause this field to be restored to the image value last loaded from EEPROM, or

OTP, or to be set to 00h if neither is present.

Offset: 060h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:24 Configuration String Descriptor Size (CFGSTR_DESC_SIZE) R/W Note 15-27

23:16 Serial Number String Descriptor Size (SERSTR_DESC_SIZE) R/W Note 15-28

15:8 Product Name String Descriptor Size (PRODSTR_DESC_SIZE) R/W Note 15-29

7:0 Manufacturing String Descriptor Size (MANUF_DESC_SIZE) R/W Note 15-30

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 167

LAN7850

15.1.18 STRING ATTRIBUTES REGISTER 1 (STRNG_ATTR1)

This register sets the length values for the named string descriptors that have been loaded into Descriptor RAM via the

Data Port registers. The Descriptor RAM images may be used, in conjunction with this register, to facilitate customized

operation when no EEPROM is present or OTP is not configured.

Note: If a descriptor does not exist in Descriptor RAM, its size value must be written as 00h.

Note: This register only affects system operation when an EEPROM is not present, OTP is not configured, and

the EEPROM Emulation Enable (EEM) bit indicates Descriptor RAM and the Attributes Registers are to be

used for descriptor processing.

Note: Writing to this register when an EEPROM is present or OTP is configured is prohibited and will result in

untoward operation and unexpected results.

Note: This register is protected by Reset Protection (RST_PROTECT).

Note 15-31 The default value of this field is determined by the value of the Interface String Descriptor Length

(bytes) contained within the EEPROM, if present. If no EEPROM is present then the value

programmed in OTP is used. If OTP is not configured then 00h is the default. A USB Reset or Lite

Reset (LRST) will cause this field to be restored to the image value last loaded from EEPROM, or

OTP, or to be set to 00h if neither is present.

15.1.19 FLAG ATTRIBUTES REGISTER (FLAG_ATTR)

This register sets the value of the GPIO PME Flags 0 and GPIO PME Flags 1 when no EEPROM is present and cus-

tomized operation, using Descriptor RAM images, is to occur.

Note 15-32 The default value of this field is determined by the value of the GPIO PME Flags 0 contained within

the EEPROM, if present. If no EEPROM is present then the value programmed in OTP is used. If

OTP is not configured then 00h is the default. A USB Reset or Lite Reset (LRST) will cause this field

Offset: 064h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:8 RESERVED RO -

7:0 Interface String Descriptor Size (INTSTR_DESC_SIZE) R/W Note 15-31

Offset: 068h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:16 RESERVED RO -

15:8 GPIO PME Flags 1 (PME_FLAGS1)

Refer to Table 10-4, “GPIO PME Flags 1,” on page 109 for bit definitions.

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W Note 15-33

7:0 GPIO PME Flags 0 (PME_FLAGS0)

Refer to Table 10-3, “GPIO PME Flags 0,” on page 108 for bit definitions.

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W Note 15-32

LAN7850

DS00001993D-page 168  2015 - 2017 Microchip Technology Inc.

to be restored to the image value last loaded from EEPROM, or OTP, or to be set to 00h if neither

is present.

Note 15-33 The default value of this field is determined by the value of the GPIO PME Flags 1 contained within

the EEPROM, if present. If no EEPROM is present then the value programmed in OTP is used. If

OTP is not configured then 00h is the default. A USB Reset or Lite Reset (LRST) will cause this field

to be restored to the image value last loaded from EEPROM, or OTP, or to be set to 00h if neither

is present.

15.1.20 SOFTWARE GENERAL PURPOSE REGISTER X (SW_GPX)

The device implements three general purpose registers for use by host software.

Offset: 06Ch - 077h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:0 Software General Purpose Register (SW_GPx)

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W 0h

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 169

LAN7850

15.1.21 USB CONFIGURATION REGISTER 0 (USB_CFG0)

Offset: 080h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31 RESERVED RO -

30 LPM Capability (LPM_CAP)

This bit enables the support of the Link Power Management (LPM) protocol.

0: LPM capability is not enabled.

1: LPM capability is enabled.

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W Note 15-36

29 Suspend Enable (SUSP_EN)

When cleared this bit prevents the SUSPEND_N pin from asserting a

suspend. Under normal operation when Suspend conditions are valid, the

USB PHY enters suspend mode when this bit is set.

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W Note 15-34

28:16 RESERVED RO -

15:13 Device Speed to Connect (DEV_SPEED)

000: High-Speed

001: Full-Speed

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W 000b

12:11 RESERVED RO -

10 USB Bulk-In Transmitter (UTX) RESET

When set, the UTX is reset.

SC 0b

9USB Bulk-Out Receiver (URX) RESET

When set, the URX is reset.

SC 0b

8:7 RESERVED RO -

6Bulk-In Empty Response (BIR)

This bit controls the response to Bulk-In tokens when the RX FIFO is empty.

0 = Respond to the IN token with a ZLP

1 = Respond to the IN token with a NAK

R/W 0b

5Burst Cap Enable (BCE)

This register enables use of the Burst Cap Register (BURST_CAP).

0 = Burst Cap register is not used to limit the TX burst size.

1 = Burst Cap register is used to limit the TX burst size.

R/W 0b

4Port Swap (PORT_SWAP)

Swaps the mapping of USB_DP and USB_DM.

0 = USB_DP maps to USB D+ and USB_DM maps to USB D-.

1 = USB_DP maps to USB D- and USB_DM maps to USB D+.

RO Note 15-35

3RESERVED RO -

LAN7850

DS00001993D-page 170  2015 - 2017 Microchip Technology Inc.

Note 15-34 The default value of this field is determined by Suspend Enable (SUSP_EN) bit of the Configuration

Flags 0 field contained within the EEPROM, if present. If no EEPROM is present then default

depends on the OTP programmed value. It the OTP is not programmed then 1b is the default. A USB

Reset or Lite Reset (LRST) will cause this field to be restored to the image value last loaded from

EEPROM, OTP, or to be set to 1b if neither is available.

Note 15-35 The default value of this field is determined by Port Swap (CFG0_PORT_SWAP) bit of the

Configuration Flags 0 field contained within the EEPROM, if present. If no EEPROM is present then

default depends on the OTP programmed value. It the OTP is not programmed then 0b is the default.

A USB Reset or Lite Reset (LRST) will cause this field to be restored to the image value last loaded

from EEPROM, OTP, or to be set to 0b if neither is available.

Note 15-36 The default value of this field is determined by the respective bit of the Configuration Flags 0 field

contained within the EEPROM, if present. If no EEPROM is present then default depends on the OTP

programmed value. It the OTP is not programmed then 1b is the default. A USB Reset or Lite Reset

(LRST) will cause this field to be restored to the image value last loaded from EEPROM, OTP, or to

be set to 1b if neither is available.

Note 15-37 The default value of this field is determined by the value of the Power Method (CFG0_PWR_SEL)

bit of Configuration Flags 0 contained within the EEPROM, if present. If no EEPROM is present, 1b

is the default. A USB Reset or Lite Reset (LRST) will cause this field to be restored to the image

value last loaded from EEPROM, or to be set to 1b if no EEPROM is present.

2Remote Wakeup Support (RMT_WKP)

0 = Device does not support remote wakeup.

1 = Device supports remote wakeup.

This bit must be set for both DEVICE_REMOTE_WAKEUP and

FUNCTION_REMOTE_WAKEUP to be supported.

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W Note 15-36

1Power Method (PWR_SEL)

This bit controls the device’s USB power mode.

0 = The device is bus powered.

1 = The device is self powered.

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W Note 15-37

0Stall Bulk-Out Pipe Disable (SBP)

This bit controls the operation of the Bulk-Out pipe when the FIFO Controller

detects the loss of sync condition. Please refer to Section 6.2.4, "TX Error

Detection" for details.

0 = Stall the Bulk-Out pipe when loss of sync detected.

1 = Do not stall the Bulk-Out pipe when loss of sync detected.

R/W 0b

BITS DESCRIPTION TYPE DEFAULT

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 171

LAN7850

15.1.22 USB CONFIGURATION REGISTER 1 (USB_CFG1)

Offset: 084h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:16 RESERVED RO -

15:13 HS Timeout Calibration (HS_TOUT_CAL)

The number of PHY clocks are indicated in this field. The controller multiplies

this number by a bit-time factor, then adds the product to the high-speed

inter-packet timeout duration in the core. This result accounts for additional

delays introduced by the PHY. This is required because the delay introduced

by generating the line-state condition varies among PHYs.

The USB standard timeout value for high-speed operation is 736 to 816

(inclusive) bit times. The number of bit times added per PHY clock are:

High-speed operation:

One 30-MHz PHY clock = 16 bit times.

One 60-MHz PHY clock = 8 bit times.

Note: Only 60 MHz operation is supported in this device.

R/W Note 15-40

12:7 RESERVED RO -

6:4 FS Timeout Calibration (FS_TOUT_CAL)

The number of PHY clocks are indicated in this field. The controller multiplies

this number by a bit-time factor, then adds the product to the full-speed inter-

packet timeout duration in the core. This result accounts for additional delays

introduced by the PHY. This is required because the delay introduced by

generating the line-state condition varies among PHYs.

The USB standard timeout value for full-speed operation is 16 to 18

(inclusive) bit times. The number of bit times added per PHY clock are:

Full-speed operation:

One 30-MHz PHY clock = 0.4 bit times.

One 60-MHz PHY clock = 0.2 bit times.

One 48-MHz PHY clock = 0.25 bit times

Note: Only 60 MHz operation is supported in this device.

R/W Note 15-41

3:2 RESERVED RO -

1:0 Scale Down Mode

Scale down mode to reduce simulation time. When Scale-Down mode is

enabled: Core uses scaled-down timing values, resulting in faster

simulations.

When Scale-Down mode is disabled: Core uses actual timing values, as

required for hardware operation.

Scale-down status for HS/FS/LS Modes

00: Disabled. Actual timing values are used.

01: Enabled for all timing values except Device mode suspend and

resume, including speed enumeration.

10: Enabled for only Device mode suspend and resume.

11: Enabled bit 0 and bit 1 scale-down values.

Note: This field is for simulation only and should be set to 00b for normal

operation.

RW 00b

LAN7850

DS00001993D-page 172  2015 - 2017 Microchip Technology Inc.

Note 15-38 The default value of this field is determined by the respective bit in of Configuration Flags 0 within

the EEPROM, if present. If no EEPROM is present then the value programmed in OTP is used. If

OTP is not configured then 0b is the default. A USB Reset or Lite Reset (LRST) will cause this field

to be restored to the image value last loaded from EEPROM, or OTP, or to be set to 0b if neither is

present.

Note 15-39 The default value of this field is determined by the respective bit in of Configuration Flags 0 within

the EEPROM, if present. If no EEPROM is present then the value programmed in OTP is used. If

OTP is not configured then 1b is the default. A USB Reset or Lite Reset (LRST) will cause this field

to be restored to the image value last loaded from EEPROM, or OTP, or to be set to 1b if neither is

present.

Note 15-40 The default value of this field is determined by the value of HS Timeout Calibration (HS_TOutCal) in

Configuration Flags 2 within the EEPROM, if present. If no EEPROM is present then the value

programmed in OTP is used. If OTP is not configured then 00h is the default. A USB Reset or Lite

Reset (LRST) will cause this field to be restored to the image value last loaded from EEPROM, or

OTP, or to be set to 00h if neither is present.

Note 15-41 The default value of this field is determined by the value of FS Timeout Calibration (FS_TOutCal) in

Configuration Flags 2 within the EEPROM, if present. If no EEPROM is present then the value

programmed in OTP is used. If OTP is not configured then 00h is the default. A USB Reset or Lite

Reset (LRST) will cause this field to be restored to the image value last loaded from EEPROM, or

OTP, or to be set to 00h if neither is present.

15.1.23 USB CONFIGURATION REGISTER 2 (USB_CFG2)

Note 15-42 The default value of this field is determined by the value of HS Detach Time (HS_DETACH) of

Configuration Flags 3 within the EEPROM, if present. If no EEPROM is present then the value

programmed in OTP is used. If OTP is not configured then 0x0A is the default. A USB Reset or Lite

Reset (LRST) will cause this field to be restored to the image value last loaded from EEPROM, or

OTP, or to be set to 0x0A if neither is present.

Offset: 088h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:16 RESERVED RO -

15:0 HS Detach Time (HS_DETACH)

Indicates amount of time, in ms, the device shall detach from the USB bus

after Soft Reset is requested when operating in high-speed or full-speed

mode.

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W Note 15-42

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 173

LAN7850

15.1.24 BURST CAP REGISTER (BURST_CAP)

This register is used to limit the size of the data burst transmitted by the USB Bulk-In Transmitter (UTX). When the

amount specified in the BURST_CAP register is transmitted, the UTX will send a ZLP.

Note: This register must be enabled through the USB Configuration Register 0 (USB_CFG0).

15.1.25 BULK-IN DELAY REGISTER (BULK_IN_DLY)

Address: 090h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:8 RESERVED RO -

7:0 BURST_CAP

The maximum amount of contiguous data that may be transmitted by the

UTX before a ZLP or short packet is sent. This field has units of 512 bytes

for HS mode and 64 bytes for FS mode.

Note: The amount of contiguous data specified must be >= the Maximum

Frame Size (MAX_SIZE) specified in the MAC_RX register. Failure

to obey this rule may result in untoward operation and may yield

unpredictable results.

Note: The device will disable the BURST_CAP function if the setting is

less than or equal to 2048 bytes.

R/W 00h

Address: 094h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:16 RESERVED RO -

15:0 Bulk In Delay

Before sending a short packet, or ZLP, the USB Bulk-In Transmitter (UTX)

waits the delay specified by this register.

This register has units of 16.667 ns and a default interval of 34.133 us.

R/W 0800h

LAN7850

DS00001993D-page 174  2015 - 2017 Microchip Technology Inc.

15.1.26 INTERRUPT ENDPOINT CONTROL REGISTER (INT_EP_CTL)

This register determines which events cause status to be reported by the interrupt endpoint. Please refer to Section 5.5,

"Interrupt Endpoint," on page 31 for further details.

Address: 098h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31 Interrupt Endpoint Always On (INTEP_ON)

When this bit is set, an interrupt packet will always be sent at the interrupt

endpoint interval.

0 = Only allow the transmission of an interrupt packet when an interrupt

source is enabled and occurs.

1 = Always transmit an interrupt packet at the interrupt interval.

R/W 0b

30:29 RESERVED RO -

28 OTP Write Done Enable (OTP_WR_DONE_EN)

0 = This event can not cause an interrupt packet to be issued.

1 = This event can cause an interrupt packet to be issued.

R/W 0b

27 RESERVED RO -

26 Energy Efficient Ethernet Start TX Low Power Enable

(EEE_START_TX_LPI_EN)

0 = This event can not cause an interrupt packet to be issued.

1 = This event can cause an interrupt packet to be issued.

R/W 0b

25 Energy Efficient Ethernet Stop TX Low Power Enable

(EEE_STOP_TX_LPI_EN)

0 = This event can not cause an interrupt packet to be issued.

1 = This event can cause an interrupt packet to be issued.

R/W 0b

24 Energy Efficient Ethernet RX Low Power Enable (EEE_RX_LPI_EN)

0 = This event can not cause an interrupt packet to be issued.

1 = This event can cause an interrupt packet to be issued.

R/W 0b

23 MAC Reset Time Out (MACRTO_EN)

0 = This event can not cause an interrupt packet to be issued.

1 = This event can cause an interrupt packet to be issued.

R/W 0b

22 RX Data FIFO Overflow Enable (RDFO_EN)

0 = This event can not cause an interrupt packet to be issued.

1 = This event can cause an interrupt packet to be issued.

R/W 0b

21 Transmit Error Enable (TXE_EN)

0 = This event can not cause an interrupt packet to be issued.

1 = This event can cause an interrupt packet to be issued.

R/W 0b

20 USB Status Interrupt Enable (USB_STS_EN)

0 = This event can not cause an interrupt packet to be issued.

1 = This event can cause an interrupt packet to be issued.

R/W 0b

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 175

LAN7850

19 TX Disabled Interrupt Enable (TX_DIS_EN)

0 = This event can not cause an interrupt packet to be issued.

1 = This event can cause an interrupt packet to be issued.

R/W 0b

18 RX Disabled Interrupt Enable (RX_DIS_EN)

0 = This event can not cause an interrupt packet to be issued.

1 = This event can cause an interrupt packet to be issued.

R/W 0b

17 PHY Interrupt Enable (PHY_EN)

0 = This event can not cause an interrupt packet to be issued.

1 = This event can cause an interrupt packet to be issued.

R/W 0b

16 Data Port Interrupt Enable (DP_EN)

0 = This event can not cause an interrupt packet to be issued.

1 = This event can cause an interrupt packet to be issued.

R/W 0b

15 MAC Error Interrupt Enable (MAC_ERR_EN)

0 = This event can not cause an interrupt packet to be issued.

1 = This event can cause an interrupt packet to be issued.

R/W 0b

14 TX Data FIFO Under-run Interrupt Enable (TDFU_EN)

0 = This event can not cause an interrupt packet to be issued.

1 = This event can cause an interrupt packet to be issued.

R/W 0b

13 TX Data FIFO Overrun Interrupt Enable (TDFO_EN)

0 = This event can not cause an interrupt packet to be issued.

1 = This event can cause an interrupt packet to be issued.

R/W 0b

12 USB Bulk-In Transmitter (UTX) Frame Pending Enable (UTX_FP_EN)

0 = This event can not cause an interrupt packet to be issued.

1 = This event can cause an interrupt packet to be issued.

R/W 0b

11:0 GPIOx Interrupt Enable (GPIOx_EN)

0 = This event can not cause an interrupt packet to be issued.

1 = This event can cause an interrupt packet to be issued.

R/W 0b

BITS DESCRIPTION TYPE DEFAULT

LAN7850

DS00001993D-page 176  2015 - 2017 Microchip Technology Inc.

15.1.27 PIPE CONTROL REGISTER (PIPE_CTL)

Note 15-43 The default value of this field is determined by the value of the TX Swing (TxSwing) bit of

Configuration Flags 1 contained within the EEPROM, if present. If no EEPROM is present then

default depends on the OTP programmed value. It the OTP is not programmed then 0b is the default.

A USB Reset or Lite Reset (LRST) shall cause this field to be restored to the image value last loaded

from EEPROM, OTP, or to be set to 0b if neither is available.

Note 15-44 The default value of this field is determined by the value of the TX Margin (TxMargin) bit of

Configuration Flags 1 contained within the EEPROM, if present. If no EEPROM is present then

default depends on the OTP programmed value. It the OTP is not programmed then 0b is the default.

A USB Reset or Lite Reset (LRST) shall cause this field to be restored to the image value last loaded

from EEPROM, OTP, or to be set to 0b if neither is available.

Note 15-45 The default value of this field is determined by the value of the TX Deemphasis (TxDeemphasis) bit

of Configuration Flags 1 contained within the EEPROM, if present. If no EEPROM is present then

default depends on the OTP programmed value. It the OTP is not programmed then 0b is the default.

A USB Reset or Lite Reset (LRST) shall cause this field to be restored to the image value last loaded

from EEPROM, OTP, or to be set to 0b if neither is available.

Note 15-46 The default value of this field is determined by the value of the Elasticity Buffer Mode

(ElasticityBufferMode) bit of Configuration Flags 1 contained within the EEPROM, if present. If no

EEPROM is present then default depends on the OTP programmed value. It the OTP is not

programmed then 0b is the default. A USB Reset or Lite Reset (LRST) shall cause this field to be

restored to the image value last loaded from EEPROM, OTP, or to be set to 0b if neither is available.

Address: 09Ch Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:7 RESERVED RO -

6TX Swing (TxSwing)

Refer to table 5-3 of the PIPE3 specification.

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W Note 15-43

5:3 TX Margin (TxMargin)

Refer to table 5-3 of the PIPE3 specification.

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W Note 15-44

2:1 TX Deemphasis (TxDeemphasis)

Refer to table 5-3 of the PIPE3 specification.

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W Note 15-45

0Elasticity Buffer Mode (ElasticityBufferMode)

Refer to table 5-3 of the PIPE3 specification.

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W Note 15-46

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 177

LAN7850

15.1.28 USB STATUS REGISTER (USB_STATUS)

Bits 15:0 of this CSR are used to generate the USB_STS_INT bit of the Interrupt EP. They indicate a change in the state

of the respective bit. When applicable, the current state of the bit is listed in the mirror bit location in bits 31:16.

Address: 0A8h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:21 RESERVED RO -

20 Remote Wakeup (REMOTE_WK)

Indicates the current state of Device Remote Wakeup.

RO/

NALR

19 Function Remote Wakeup (FUNC_REMOTE_WK)

Indicates the current state of Function Remote Wakeup Capable.

RO/

NALR

18:5 RESERVED RO -

4Remote Wakeup Status Change (REMOTE_WK_STS)

Indicates that the host set or cleared Device Remote Wakeup.

R/WC 0b

3Function Remote Wakeup Status Change (FUNC_REMOTE_WK_STS)

Indicates that the host set or cleared Function Remote Wake Capable

R/WC 0b

2:0 RESERVED RO -

LAN7850

DS00001993D-page 178  2015 - 2017 Microchip Technology Inc.

15.1.29 RECEIVE FILTERING ENGINE CONTROL REGISTER (RFE_CTL)

This register configures the Receive Filtering Engine (RFE).

If neither Enable IGMP Checksum Validation, Enable ICMP Checksum Validation or Enable TCP/UDP Checksum Val-

idation bits are set, then the RFE inserts 0000h for the L3 raw checksum field.

Offset: 0B0h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:16 RESERVED RO -

15 Always Pass Wakeup Frame (PASS_WKP)

When set, the RFE shall never discard a received wakeup frame which

awakened the device while in SUSPEND3 and Store Wakeup Frame

(STORE_WAKE) is set.

R/W 0b

14 Enable IGMP Checksum Validation

When set, the RFE will check the IGMP checksum.

Additionally, the RFE calculates the L3 raw checksum and inserts it into RX

Status Word 1.

Note: If the frame is not IGMP raw checksum is still calculated.

R/W 0b

13 Enable ICMP Checksum Validation

When set, the RFE will check the ICMP checksum.

Additionally, the RFE calculates the L3 raw checksum and inserts it into RX

Status Word 1.

Note: If the frame is not ICMP raw checksum is still calculated.

R/W 0b

12 Enable TCP/UDP Checksum Validation

When set, the RFE will check the TCP or UDP checksum.

Additionally, the RFE calculates the L3 raw checksum and inserts it into RX

Status Word 1.

Note: If the frame is not TCP or UDP the raw checksum is still calculated.

R/W 0b

11 Enable IP Checksum Validation

When set, the RFE will check the IP checksum.

This bit has no effect if the frame is not IPv4 or IPv6.

R/W 0b

10 Accept Broadcast Frames (AB)

When set, all broadcast frames are accepted. Otherwise broadcast frames

are dropped.

R/W 0b

9Accept Multicast Frames (AM)

When set, all multicast frames are accepted. Otherwise multicast frames

must pass the perfect filtering or hash filtering.

Note: This bit does not apply to broadcast frames.

R/W 0b

8Accept Unicast Frames (AU)

When set, all unicast frames are accepted.

R/W 0b

7Enable VLAN Tag Stripping

When set, this bit enables stripping of a received frame’s VLAN ID.

R/W 0b

6Untagged Frame Filtering (UF)

When set, all untagged receive frames are discarded.

R/W 0b

5Enable VLAN Filtering (VF)

When set, this bit enables filtering of a received frame’s VLAN ID.

R/W 0b

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 179

LAN7850

15.1.30 VLAN TYPE REGISTER (VLAN_TYPE)

This register extends the Ethernet type used to indicate the presence of a VLAN tag in the RFE in addition to 8100h. In

the FCT this is the value used for the Ethernet type when VLAN tag insertion is enabled.

The intention of this register is to allow for a proprietary VLAN type to be supported. If only the standard VLAN type of

8100h is desired to be supported, then this register should retain its default value of 8100h.

4Enable Source Address Perfect Filtering (SPF)

When set, this bit enables perfect filtering of a received frame’s Ethernet

source address.

Note: If destination address filtering is enabled (perfect or hash), the

frame must pass both source address filtering and destination

address filtering to not be discarded.

R/W 0b

3Enable Multicast Address Hash Filtering (MHF)

When set, multicast destination addresses will be hashed.

Note: The broadcast address is never hashed.

R/W 0b

2Enable Destination Address Hash Filtering (DHF)

When set, unicast destination addresses will be hashed.

R/W 0b

1Enable Destination Address Perfect Filtering (DPF)

When set, this bit enables perfect filtering of a received frame’s Ethernet

destination address.

R/W 0b

0Reset Receive Filtering Engine

When set, this bit resets the RFE.

SC 0b

Offset: 0B4h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:16 RESERVED RO -

15:0 VLAN Ethernet Type R/W 8100h

BITS DESCRIPTION TYPE DEFAULT

LAN7850

DS00001993D-page 180  2015 - 2017 Microchip Technology Inc.

15.1.31 FIFO CONTROLLER RX FIFO CONTROL REGISTER (FCT_RX_CTL)

Offset: 0C0h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31 FCT RX Enable

When set, the FIFO is capable of accepting traffic from the RFE. If this bit

is deasserted, all received frames from the RFE are aborted and not written

into the FIFO. After this bit is asserted, the FIFO will accept the next full

frame it receives.

After the FIFO is enabled, the FIFO begins accepting data after it receives

the first complete frame. If the FIFO is disabled while receiving a frame, the

FIFO will allow the current frame to be received before disabling the FIFO.

After the FIFO is successfully disabled the FCT RX Disabled bit is asserted.

Note: This bit does not cause frame dropped counter to increment.

R/W 0b

30 FCT RX RESET

When set, the FCT RX is reset. It also clears any remnant data from the

FIFO stored in the UTX interface pipeline.

The FIFO must be disabled before a reset is issued.

SC f

29:26 RESERVED RO -

25 Store Bad Frames

When set, the RX FCT will store errored frames that were detected by the

Ethernet MAC.

The following conditions cause the MAC to consider a frame bad: RX error,

FCS error, runt frame, alignment error, jabber error, undersize frame error,

and oversize frame error.

R/W 0b

24 FCT RX Overflow R/WC 0b

23 RX Frame Dropped

See RX Dropped Frames for a description

R/WC 0b

22:21 RESERVED RO -

20 FCT RX Disabled

This bit indicates the FIFO has been successfully disabled via clearing the

FCT RX Enable bit. It is set when the hardware disabling process, invoked

by a transition of the FCT RX Enable bit from 1 to 0 (enabled to disabled),

completes.

R/WC 0b

19:16 RESERVED RO -

15:0 RX Data FIFO Used Space (RXUSED)

Reads the amount of space in bytes, used by the FIFO. For each frame, this

field is incremented by the length of the frame rounded up to the nearest

DWORD (if the payload does not end on a DWORD boundary). Additionally

any Command Words or checksums associated with the frame are also

added in.

RO 0000h

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 181

LAN7850

15.1.32 FIFO CONTROLLER TX FIFO CONTROL REGISTER (FCT_TX_CTL)

15.1.33 FCT RX FIFO END REGISTER (FCT_RX_FIFO_END)

This register specifies the end address of the RX FIFO in DWORD units. The contents of this register times 128 plus

127 is the end address of the FIFO.

Note: This register’s contents may not be modified at run time. The RX data path must be halted before changing

the FIFO size. After modifying the FIFO’s size, the FIFO must be flushed.

Note: Maximum RX FIFO size is 12 KB which is the.default value.

Offsets: 0C4h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31 FCT TX Enable

When set, the FIFO is capable of transmitting frames to the MAC.

If the FIFO is disabled while transmitting a frame, the frame transmission is

allowed to complete. Upon completion of the last frame FCT TX Disabled bit

is asserted.

An exception to the above can happen in half duplex mode in which the

FIFO may discard the frame in transmit. This case happens when the frame

in transmit is retried by the MAC after the FIFO has been disabled. The FIFO

does not allow any further retries.

R/W 0b

30 FCT TX Reset

When set, this bit resets the FCT TX. It also clears any remnant data from

the FIFO stored in the URX interface pipeline.

The FIFO must be disabled before a reset is issued.

SC 0b

29:21 RESERVED RO -

20 FCT TX Disabled

This bit indicates the FIFO has been successfully disabled via clearing the

FCT TX Enable bit. It is set when the hardware disabling process, invoked

by a transition of the FCT TX Enable bit from 1 to 0 (enabled to disabled),

completes.

R/WC 0b

19:16 RESERVED RO -

15:0 TX Data FIFO Used Space (TXUSED)

Reads the amount of space in bytes, used by the FIFO. For each frame, this

field is incremented by the length of the frame rounded up to the nearest

DWORD (if the payload does not end on a DWORD boundary). Additionally

any Command Words or checksums associated with the frame are also

added in.

RO 0000h

Offset: 0C8h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:7 RESERVED RO -

6:0 FCT_RX_FIFO_END R/W 17h

LAN7850

DS00001993D-page 182  2015 - 2017 Microchip Technology Inc.

15.1.34 FCT TX FIFO END REGISTER (FCT_TX_FIFO_END)

This register specifies the end address of the TX FIFO in DWORD units. The contents of this register times 128 plus

127 is the end address of the FIFO.

Note: This register’s contents may not be modified at run time. The TX data path must be halted before changing

the FIFO size. After modifying the FIFO’s size, the FIFO must be flushed.

Note: Maximum TX FIFO size is 12 KB which is the default.

15.1.35 FCT FLOW CONTROL THRESHOLD REGISTER (FCT_FLOW)

This register specifies the thresholds for controlling pause frame generation. The units of the thresholds are 512 bytes

and correspond to high and low watermarks in the RX FIFO.

Note: The values in this register must be programmed before the TX Flow Control Enable (TX_FCEN) bit is set.

Please refer to Section 15.1.41, "Flow Control Register (FLOW)," on page 189 for further details.

Offset: 0CCh Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:6 RESERVED RO -

5:0 FCT_TX_FIFO_END R/W 17h

Offset: 0D0h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:15 RESERVED RO -

14:8 Flow Control Off Threshold

The threshold to turn flow control off. If RX Data FIFO Used Space

(RXUSED) / 512 is less than or equal to this value, then flow control is turned

off.

R/W 0000000b

7RESERVED RO -

6:0 Flow Control On Threshold

The threshold to turn flow control on. If RX Data FIFO Used Space

(RXUSED) / 512 is greater than or equal to this value, then flow control is

turned on.

R/W 0000000b

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 183

LAN7850

15.1.36 RX DATAPATH STORAGE (RX_DP_STOR)

15.1.37 TX DATAPATH STORAGE (TX_DP_STOR)

Offset: 0D4h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:16 Total RX Data Path Used Space (TOT_RXUSED)

Reads the amount of space in bytes, used by both the UTX FIFO and FCT

RX FIFO.

RO 0000h

15:0 UTX FIFO Used Space (UTX_RXUSED)

Reads the amount of space in bytes, used by the UTX FIFO.

RO 0000h

Offset: 0D8h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:16 Total TX Data Path Used Space (TOT_TXUSED)

Reads the amount of space in bytes, used by both the URX FIFO and FCT

TX FIFO.

RO 0000h

15:0 URX FIFO Used Space (URX_TXUSED)

Reads the amount of space in bytes, used by the URX FIFO.

RO 0000h

LAN7850

DS00001993D-page 184  2015 - 2017 Microchip Technology Inc.

15.1.38 MAC CONTROL REGISTER (MAC_CR)

This register establishes the RX and TX operating modes.

Offset: 100h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:19 RESERVED RO -

18 Energy Efficient Ethernet TX Clock Stop Enable

(EEE_TX_CLK_STOP_EN)

When set, the MAC will halt the GMII GTX_CLK to the PHY during TX LPI.

This bit is unused in 100Mbs mode.

This bit should only be set if the Clock stop capable bit in PHY MMD register

3.1 indicates that the PHY is capable of allowing a stopped TX clock.

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W Note 15-47

17 Energy Efficient Ethernet Enable (EEEEN)

When set, enables Energy Efficient Ethernet operation in the MAC. When

cleared, Energy Efficient Ethernet operation is disabled. Note 15-48

The MAC will generate LPI requests even if Transmitter Enable (TXEN) is

cleared and will decode the LPI indication even if Receiver Enable (RXEN)

is cleared.

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W Note 15-47

16 Energy Efficient Ethernet TX LPI Automatic Removal Enable

(EEE_TX_LPI_AUTO_REMOVAL_EN)

When set, enables the automatic deassertion of LPI in anticipation of a

periodic transmission event. The time to wait is specified in the EEE TX LPI

Automatic Removal Delay Register

(EEE_TX_LPI_AUTO_REMOVAL_DELAY). The interval is timed from the

point where the MAC initiates LPI signaling.

Host software should only change this field when Energy Efficient Ethernet

Enable (EEEEN) is cleared.

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W Note 15-47

15:14 RESERVED RO -

13 Automatic Duplex Polarity (ADP)

This bit indicate the polarity of the FDUPLEX PHY LED.

0: DUPLEX asserted low indicates the PHY is in full duplex mode.

1: DUPLEX asserted high indicates the PHY is in full duplex mode.

Note: This bit should not be modified while the MAC's receiver or

transmitter is enabled (Receiver Enable (RXEN) or Transmitter

Enable (TXEN) bit set).

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W 1b

12 Automatic Duplex Detection (ADD)

When set, the MAC ignores the setting of the Duplex Mode (DPX) bit and

automatically determines the duplex operational mode. The MAC uses a

PHY LED/signal to accomplish mode detection and reports the last

determined status via the Duplex Mode (DPX) bit. When reset, the setting of

the Duplex Mode (DPX) bit determines Duplex operation.

Note: This bit should not be modified while the MAC's receiver or

transmitter is enabled (Receiver Enable (RXEN) or Transmitter

Enable (TXEN) bit set).

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W Note 15-49

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 185

LAN7850

11 Automatic Speed Detection (ASD)

When set, the MAC ignores the setting of the MAC Configuration (CFG) field

and automatically determines the speed of operation. The MAC samples the

RX_CLK input to accomplish speed detection and reports the last

determined speed via the MAC Configuration (CFG) field. When reset, the

setting of the MAC Configuration (CFG) field determines operational speed.

Note: This bit should not be modified while the MAC's receiver or

transmitter is enabled (Receiver Enable (RXEN) or Transmitter

Enable (TXEN) bit set).

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W Note 15-50

10 Internal Loopback Operation Mode (INT_LOOP)

Loops back data between the TX data path and RX data path interfaces.

This is only for full duplex mode.

In internal loopback mode, the TX frame is received by the Internal GMII

interface, and sent back to the MAC without being sent to the PHY.

0: Normal mode

1: Internal loopback enabled

Note: This bit should not be modified while the MAC's receiver or

transmitter is enabled (Receiver Enable (RXEN) or Transmitter

Enable (TXEN) bit set).

R/W 0b

9:8 RESERVED RO -

7:6 Back Off Limit (BOLMT)

The BOLMT bits allow the user to set its back-off limit in a relaxed or

aggressive mode. According to IEEE 802.3, the MAC has to wait for a

random number [r] of slot-times after it detects a collision, where:

(eq.1)0 < r < 2K

The exponent K is dependent on how many times the current frame to be

transmitted has been retried, as follows:

(eq.2)K = min (n, 10) where n is the current number of retries.

If a frame has been retried three times, then K = 3 and r= 8 slot-times

maximum. If it has been retried 12 times, then K = 10, and r = 1024 slot-

times maximum.

An LFSR (linear feedback shift register) counter emulates a random number

generator, from which r is obtained. Once a collision is detected, the number

of the current retry of the current frame is used to obtain K (eq.2). This value

of K translates into the number of bits to use from the LFSR counter. If the

value of K is 3, the MAC takes the value in the first three bits of the LFSR

counter and uses it to count down to zero on every slot-time. This effectively

causes the MAC to wait eight slot-times. To give the user more flexibility, the

BOLMT value forces the number of bits to be used from the LFSR counter

to a predetermined value as in the table below.

Thus, if the value of K = 10, the MAC will look at the BOLMT if it is 00, then use

the lower ten bits of the LFSR counter for the wait countdown. If the BOLMT is 10,

then it will only use the value in the first four bits for the wait countdown, etc.

Slot-time = 512 bit times. (See IEEE 802.3 Spec., Sections 4.2.3.2.5 and

4.4.2.1).

Note: This bit should not be modified while the MAC's receiver or

transmitter is enabled (Receiver Enable (RXEN) or Transmitter

Enable (TXEN) bit set).

R/W 00b

5:4 RESERVED RO -

BITS DESCRIPTION TYPE DEFAULT

LAN7850

DS00001993D-page 186  2015 - 2017 Microchip Technology Inc.

Note 15-47 The default value of this field is determined by the value of the respective field in Configuration Flags

2 contained within the EEPROM, if present. If no EEPROM is present then default depends on the

OTP programmed value. It the OTP is not programmed then 0h is the default. A USB Reset or Soft

Lite Reset (LRST) shall cause this field to be restored to the image value last loaded from EEPROM,

OTP, or to be set to 0h if neither is available.

Note 15-48 If this bit is manually changed, then the EEE configuration in the Ethernet PHY must be updated and

auto-negotiation rerun.

Note 15-49 The default value of this field is determined by the value of the Automatic Duplex Detection

(CFG0_ADD) bit of Configuration Flags 0 contained within the EEPROM, if present. If no EEPROM

is present then default depends on the OTP programmed value. It the OTP is not programmed then

1b is the default. A USB Reset or Soft Lite Reset (LRST) shall cause this field to be restored to the

image value last loaded from EEPROM, OTP, or to be set to 1b if neither is available.

Note 15-50 The default value of this field is determined by the value of the Automatic Speed Detection

(CFG0_ASD) bit of Configuration Flags 0 contained within the EEPROM, if present. If no EEPROM

is present then default depends on the OTP programmed value. It the OTP is not programmed then

0b is the default. A USB Reset or Soft Lite Reset (LRST) shall cause this field to be restored to the

image value last loaded from EEPROM, OTP, or to be set to 0b if neither is available.

Note 15-51 When Automatic Duplex Detection (ADD) is reset, this bit is R/W and determines duplex operation.

When Automatic Duplex Detection (ADD) is set, this field is RO and reports the last duplex

operational mode determined by the MAC.

3Duplex Mode (DPX)

This bit determines the duplex operational mode of the MAC when the

Automatic Duplex Detection (ADD) bit is reset. When the Automatic Duplex

Detection (ADD) bit is set, this bit is read-only and reports the last

determined duplex operational mode.

When set, the MAC is operating in Full-Duplex mode, in which it can transmit

and receive simultaneously.

0: MAC is in half duplex mode

1: MAC is in full duplex mode

Note: This bit should not be modified while the MAC's receiver or

transmitter is enabled (Receiver Enable (RXEN) or Transmitter

Enable (TXEN) bit set).

Note: Half duplex mode is disabled if the detected or manually set speed

is 1000Mbs, regardless of the setting of this bit.

Note: This field is protected by Reset Protection (RST_PROTECT).

Note 15-

Note 15-47

2:1 MAC Configuration (CFG)

This field determines the operational speed of the MAC when the Automatic

Speed Detection (ASD) bit is reset. When the Automatic Speed Detection

(ASD) bit is set, this field is read-only and reports the last determined

operational speed.

0: MII Mode - 10 Mbps

1: MII Mode - 100 Mbps

2,3: RGMII/GMII Mode - 1000 Mbps

Note: This bit should not be modified while the MAC's receiver or

transmitter is enabled (Receiver Enable (RXEN) or Transmitter

Enable (TXEN) bit set).

Note: This field is protected by Reset Protection (RST_PROTECT).

Note 15-

Note 15-47

0MAC Reset (MRST)

0: MAC is enabled

1: MAC is reset

SC 0b

BITS DESCRIPTION TYPE DEFAULT

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 187

LAN7850

Note 15-52 When Automatic Speed Detection (ASD) is reset, this field is R/W and determines operational speed.

When Automatic Speed Detection (ASD) is set, this field is RO and reports the last operational speed

determined by the MAC.

15.1.39 MAC RECEIVE REGISTER (MAC_RX)

Offset: 104h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:30 RESERVED RO -

29:16 Maximum Frame Size (MAX_SIZE)

Defines the maximum size for a received frame. Frames exceeding this size

are aborted.

Note: A frame longer than 11,264 bytes will cause the watchdog timer to

truncate and abort the frame.

Note: This field should not be modified while the MAC's receiver is

enabled (Receiver Enable (RXEN) bit set in MAC Receive Register

(MAC_RX)).

R/W 1518

15:6 RESERVED RO -

5Watchdog Truncation Length (WTL)

0: The MAC truncates the Rx FRAME at MAC_RX.MAX_SIZE+1. The

RxCmdA of the truncated received frame passed to the FCT has LONG bit

set and length MAC_RX.MAX_SIZE+1 and FCS likely set.

1: The MAC truncates the Rx FRAME at 11265. The RxCmdA of the

truncated received frame passed to the FCT has LONG bit set and length

11265 and FCS more than likely set and RWT bit set also.

Note: This bit should not be modified while the MAC's receiver is enabled

(Receiver Enable (RXEN) bit set in MAC Receive Register

(MAC_RX)).

R/W 1b

4FCS Stripping

When set, the MAC will strip the FC (last 4 bytes) off of all received frames.

Note: This bit should not be modified while the MAC's receiver is enabled

(Receiver Enable (RXEN) bit set in MAC Receive Register

(MAC_RX)).

R/W 0b

3RESERVED RO -

2VLAN Frame Size Enforcement (FSE)

0: Abort all frames larger than the maximum frame size.

1: Abort all non-VLAN frames larger than maximum frame size. Abort all

frames with a single VLAN tag that are larger the maximum frame size + 4.

Abort all frames with two VLAN tags that are larger than the maximum frame

size + 8.

Note: This bit should not be modified while the MAC's receiver is enabled

(Receiver Enable (RXEN) bit set in MAC Receive Register

(MAC_RX)).

R/W 0b

1Receiver Disabled (RXD)

This bit indicates the MAC’s receiver has been successfully disabled via

clearing the Receiver Enable (RXEN) bit. It is set when the hardware

disabling process, invoked by a transition of the Receiver Enable (RXEN) bit

from 1 to 0 (enabled to disabled), completes.

R/WC 0b

LAN7850

DS00001993D-page 188  2015 - 2017 Microchip Technology Inc.

15.1.40 MAC TRANSMIT REGISTER (MAC_TX)

0Receiver Enable (RXEN)

When set, the MAC’s receiver is enabled and will receive frames from the

PHY. When reset, the MAC’s receiver is disabled and will not receive any

frames from the PHY.

If this bit is deasserted while a frame is being received, the received frames

allowed to complete. Upon completion, the MAC’s receiver is disabled and

the Receiver Disabled (RXD) bit is asserted.

R/W 0b

Offset: 108h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:3 RESERVED RO -

2Bad FCS (BFCS)

When set, the MAC’s transmitter will append a bad FCS on all transmitted

frames. This feature is useful for diagnostic purposes.

This function may only be used in conjunction with Insert FCS and Pad of

TX Command A.

R/W 0b

1Transmitter Disabled (TXD)

This bit indicates the MAC’s transmitter has been successfully disabled via

clearing the Transmitter Enable (TXEN) bit. It is set when the hardware

disabling process, invoked by a transition of the Transmitter Enable (TXEN)

bit from 1 to 0 (enabled to disabled), completes.

R/WC 0b

0Transmitter Enable (TXEN)

When set, the MAC’s transmitter is enabled and it will transmit frames from

the buffer onto the cable. When reset, the MAC’s transmitter is disabled and

will not transmit any frames.

If this bit is cleared while a frame is being transmitted, the frame is allowed

to complete. Upon completion, the MAC’s transmitter is disabled and the

Transmitter Disabled (TXD) bit is asserted.

R/W 0b

BITS DESCRIPTION TYPE DEFAULT

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 189

LAN7850

15.1.41 FLOW CONTROL REGISTER (FLOW)

This register is used to control the handling of the RX and TX flow control frames by the MAC.

RX flow control frames are received by the MAC. When RX flow control is enabled, the MAC will pause transmissions

from the transmit data path for the amount of time specified in the flow control frame.

TX flow control frames may be generated manually or automatically using RX FIFO thresholds. By setting the

FORCE_FC bit, a flow control frame will be manually transmitted with the value specified by Pause Time (FCPT). After

the frame is transmitted, the FORCE_FC bit clears.

Whenever TX_FCEN is set, transmit flow control frames are generated automatically, based on the thresholds set in the

FCT Flow Control Threshold Register (FCT_FLOW). Whenever the high watermark is crossed (RX Data FIFO Used

Space (RXUSED) / 512 greater than or equal to Flow Control On Threshold), the MAC transmits a flow control frame

with the pause value specified by the Pause Time (FCPT) field. When the low watermark is subsequently crossed (RX

Data FIFO Used Space (RXUSED) / 512 less than or equal to Flow Control Off Threshold), the MAC transmits a flow

control frame with a pause value of zero.

Flow Control is only applicable when the MAC is set in full duplex mode.

Offset: 10Ch Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31 Force Transmission of TX Flow Control Frame (FORCE_FC)

This bit forces the transmission of a TX flow control frames. Writing a “1”

initiates the frame transmission. The frame will be generated with the Pause

Time value. After the frame is transmitted, the MAC will clear this bit.

SC 0b

30 TX Flow Control Enable (TX_FCEN)

When set, enables the transmit MAC flow control function based on high and

low watermarks in the RX FIFO, as discussed in this section.

Note: The threshold values in the FCT Flow Control Threshold Register

(FCT_FLOW) must be programmed before this bit is set.

R/W 0b

29 RX Flow Control Enable (RX_FCEN)

When set, enables the receive MAC flow control function. The MAC decodes

all incoming frames for control frames; if it receives a valid control frame

(PAUSE command), it disables the transmitter for a specified time (Decoded

pause time x slot time). When not set, the MAC flow control function is

disabled; the MAC does not decode frames for control frames.

R/W 0b

28 Forward Pause Frames (FPF)

Enables passing received pause frames to RX data path interface.

0 = Sink received pause frames.

1 = Pass received pause frames to the RX data path interface.

Note: Flow Control is applicable when the MAC is set in full duplex mode.

R/W 0b

27:16 RESERVED RO -

15:0 Pause Time (FCPT)

This field indicates the value to be used in the PAUSE TIME field in the

control frame.

R/W 0000h

LAN7850

DS00001993D-page 190  2015 - 2017 Microchip Technology Inc.

15.1.42 RANDOM NUMBER SEED VALUE REGISTER (RAND_SEED)

15.1.43 ERROR STATUS REGISTER (ERR_STS)

Offset: 110h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:16 RESERVED RO -

15:0 Random Number Seed (RAND_SEED)

The MAC random number generator seed value. The content of this register

is the seed value for the LFSR (linear feedback shift register) counter used

to emulate the random number generator in the MAC TX back-off timer logic.

R/W 9876h

Offset: 114h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:9 RESERVED RO -

9RX Error (RXERR)

Indicates that a receive error (PHY RX error signal asserted) has been

detected during frame reception.

R/WAC 0b

8FCS Error (FERR)

An FCS errored frame has been received.

R/WAC 0b

7Large Frame Error (LFERR)

A frame larger than the maximum allow frame size has been received.

R/WAC 0b

6Runt/Short Frame Error (RFERR)

A runt frame or a short frame has been received.

R/WAC 0b

5Receive Watchdog Timer Expired (RWTERR)

When set, this bit indicates the received frame was longer than 11,264 bytes

and was truncated by the MAC.

R/WAC 0b

4Excessive Collision Error (ECERR)

A received frame was aborted due to sixteen collisions occurring.

R/WAC 0b

3Alignment Error (ALERR)

An alignment error has been detected on a received frame.

R/WAC 0b

2Under Run Error (URERR)

The MAC has been under run by the transmit data-path.

R/WAC 0b

1:0 RESERVED RO -

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 191

LAN7850

15.1.44 MAC RECEIVE ADDRESS HIGH REGISTER (RX_ADDRH)

This register contains the upper 16 bits of the physical address of the MAC, where RX_ADDRH[15:8] is the 6th octet of

the received frame.

This register used to specify the address used for Perfect DA, Magic Packet and Wakeup frames, the unicast destination

address for received pause frames, and the source address for transmitted pause frames. This register is not used for

packet filtering.

Note: This register is protected by Reset Protection (RST_PROTECT).

Note 15-53 The default value of this field is determined by the value of the MAC Address field contained within

the EEPROM, if present. If no EEPROM is present then the value programmed in OTP is used. If

OTP is not configured then FFFF_FFFFh is the default. A USB Reset will cause this field to be

restored to the value last loaded from EEPROM, or OTP, otherwise the current value in this register

will be maintained.

15.1.45 MAC RECEIVE ADDRESS LOW REGISTER (RX_ADDRL)

This register contains the lower 32 bits of the physical address of the MAC, where RX_ADDRL[7:0] is the first octet of

the Ethernet frame.

This register used to specify the address used for Perfect DA, Magic Packet, and Wakeup frames, the unicast destina-

tion address for received pause frames, and the source address for transmitted pause frames. This register is not used

for packet filtering.

This register is protected by Reset Protection (RST_PROTECT).

Note 15-54 The default value of this field is determined by the value of the MAC Address filed contained within

the EEPROM, if present. If no EEPROM is present then the value programmed in OTP is used. If

OTP is not configured then FFFF_FFFFh is the default. A USB Reset will cause this field to be

restored to the image value last loaded from EEPROM, or OTP, or to be set to FFFF_FFFFh if neither

is present.

Address: 118h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:16 RESERVED RO -

15-0 Physical Address [47:32]

This field contains the upper 16 bits [47:32] of the physical address of the

device.

R/W FFFFh

Note 15-53

Address: 11Ch Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:0 Physical Address [31:0]

This field contains the lower 32 bits [31:0] of the physical address of the

device.

R/W FFFF_FFFFh

Note 15-54

LAN7850

DS00001993D-page 192  2015 - 2017 Microchip Technology Inc.

Table 15-4 illustrates the byte ordering of the RX_ADDRL and RX_ADDRH registers with respect to the reception of the

Ethernet physical address.

15.1.46 MII ACCESS REGISTER (MII_ACCESS)

This register is used to control the management cycles to the PHY.

TABLE 15-4: RX_ADDRL, RX_ADDRH BYTE ORDERING

RX_ADDRL, RX_ADDRH ORDER OF RECEPTION ON ETHERNET

RX_ADDRL[7:0] 1st

RX_ADDRL[15:8] 2nd

RX_ADDRL[23:16] 3rd

RX_ADDRL[31:24] 4th

RX_ADDRH[7:0] 5th

RX_ADDRH[15:8] 6th

Address: 120h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:16 RESERVED RO -

15:11 PHY Address

For every access to this register, this field must be set to 00001b.

R/W 00001b

10:6 MII Register Index (MIIRINDA)

These bits select the desired MII register in the PHY.

R/W 00000b

5:2 RESERVED RO -

1MII Write (MIIWnR)

Setting this bit tells the PHY that this will be a write operation using the MII

data register. If this bit is not set, this will be a read operation, packing the

data in the MII data register.

R/W 0b

0MII Busy (MIIBZY)

This bit must be polled to determine when the MII register access is

complete. This bit must read a logical 0 before writing to this register or to

the MII data register. The LAN driver software must set (1) this bit in order

for the Host to read or write any of the MII PHY registers.

During a MII register access, this bit will be set, signifying a read or write

access is in progress. The MII data register must be kept valid until the MAC

clears this bit during a PHY write operation. The MII data register is invalid

until the MAC has cleared this bit during a PHY read operation.

SC 0b

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 193

LAN7850

15.1.47 MII DATA REGISTER (MII_DATA)

This register contains either the data to be written to the PHY register specified in the MII Access Register, or the read

data from the PHY register whose index is specified in the MII Access Register. Refer to Section 15.1.46, "MII Access

Note: The MIIBZY bit in the MII_ACCESS register must be cleared when writing to this register.

15.1.48 EEE TX LPI REQUEST DELAY COUNT REGISTER (EEE_TX_LPI_REQUEST_DELAY_CNT)

Contains the count corresponding to the amount of time, in us, the MAC must wait after the TX FIFO is empty before

invoking the LPI protocol.

Whenever the TX FIFO is empty, the device checks the Energy Efficient Ethernet Enable (EEEEN) bit of the MAC Con-

trol Register (MAC_CR) to determine whether or not the Energy Efficient Ethernet mode of operation is in effect. If the

bit is clear, no action is taken, otherwise, the device waits the amount of time indicated in this register. After the wait

period has expired, the LPI protocol is initiated and the Energy Efficient Ethernet Start TX Low Power Interrupt

(EEE_START_TX_LPI_INT) bit of the Interrupt Status Register (INT_STS) will be set.

Note: Due to a 1us pre-scaler, the actually time can be up to 1us longer than specified.

Note: A value of zero is valid and will cause no delay to occur.

If the TX FIFO becomes non-empty, the timer is restarted.

APPLICATION NOTE: A value of zero may adversely affect the ability of the TX data path to support Gigabit

operation. A reasonable value when the part is operating at Gigabit speeds is 50 us. This

value may be increased pending the results of performance testing with EEE enabled. The

motivation for 802.3az is the scenario where the EEE link is idle most of the time with the

occasional full bandwidth transmission bursts. Aggressively optimizing power consumption

during pockets of inactivity is not the objective for this mode of operation.

Address: 124h Size: 32 bits

BITS DESCRIPTION

31:16 RESERVED RO -

15:0 MII Data

This contains the 16-bit value read from the PHY read operation or the 16-

bit data value to be written to the PHY before an MII write operation.

R/W 0000h

Offset: 130h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:0 EEE TX LPI Request Delay Count

(EEE_TX_LPI_REQUEST_DELAY_CNT)

Count representing time to wait before invoking LPI protocol. Units are in us.

Note: Host software should only change this field when Energy Efficient

Ethernet Enable (EEEEN) is cleared.

R/W 00000000h

LAN7850

DS00001993D-page 194  2015 - 2017 Microchip Technology Inc.

15.1.49 EEE TIME WAIT TX SYSTEM REGISTER (EEE_TW_TX_SYS)

Contains the count corresponding to the amount of time, in us, the MAC must wait after LPI is exited before it can trans-

mit packets. Time is specified in separate fields for 100Mbs and 1000Mbs operation. This wait time is in addition to the

IPG time.

Offset: 134h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:16 EEE TIME Wait TX System Count 1000 (EEE_TW_TX_SYS_CNT_1000)

Count representing time to wait before commencing transmission after LPI

is exited when operating at 1000Mbs. Units are in 0.5 us.

Host software should only change this field when Energy Efficient Ethernet

Enable (EEEEN) is cleared.

Note: In order to meet the IEEE 802.3 specified requirement, the

minimum value of this field should be 000021h.

R/W 000021h

15:0 EEE TIME Wait TX System Count 100 (EEE_TW_TX_SYS_CNT_100)

Count representing time to wait before commencing transmission after LPI

is exited when operating at 100Mbs. Units are in us.

Host software should only change this field when Energy Efficient Ethernet

Enable (EEEEN) is cleared.

Note: In order to meet the IEEE 802.3 specified requirement, the

minimum value of this field should be 00001Eh.

R/W 00001Eh

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 195

LAN7850

15.1.50 EEE TX LPI AUTOMATIC REMOVAL DELAY REGISTER

(EEE_TX_LPI_AUTO_REMOVAL_DELAY)

Contains the count corresponding to the amount of time, in us, the MAC will wait after the TX LPI protocol is initiated

until it automatically deasserts LPI in anticipation of a periodic transmission. TX LPI automatic removal functionality is

enabled via the Energy Efficient Ethernet TX LPI Automatic Removal Enable (EEE_TX_LPI_AUTO_REMOVAL_EN) bit

of the MAC Control Register (MAC_CR).

When this time period expires, the Energy Efficient Ethernet Stop TX Low Power Interrupt (EEE_STOP_TX_LPI_INT)

bit of the Interrupt Status Register (INT_STS) and the Energy Efficient Ethernet TX Wake (EEE_TX_WAKE) bit of the

Wakeup Control and Status Register 1 (WUCSR1) will be set.

Upon automatic TX LPI deassertion, the MAC will return to waiting for the TX FIFO to be empty, for the time specified

in EEE TX LPI Request Delay Count (EEE_TX_LPI_REQUEST_DELAY_CNT) before requesting LPI once again.

Note: Due to a 1 us pre-scaler, the actually time can be up to 1us longer than specified.

The MAC will generate LPI requests only when the Energy Efficient Ethernet Enable (EEEEN) bit of the MAC Control

ation result indicates that both the local and partner device support EEE at the current operating speed.

Offset: 138h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:24 RESERVED RO -

23:0 EEE TX LPI Automatic Removal Delay Count

(EEE_TX_LPI_AUTO_REMOVAL_DELAY_CNT)

Count representing time to wait after the TX LPI protocol is initiated until it

is automatically deasserted in anticipation of a periodic transmission. Units

are in us.

Note: Host software should only change this field when Energy Efficient

Ethernet Enable (EEEEN) is cleared.

R/W 000000h

LAN7850

DS00001993D-page 196  2015 - 2017 Microchip Technology Inc.

15.1.51 WAKEUP CONTROL AND STATUS REGISTER 1 (WUCSR1)

This register contains data pertaining to the MAC’s remote wakeup status and capabilities.

All enables within this register must be clear during normal operation. Failure to do so will result in improper MAC receive

operation.

Offset: 140h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:15 RESERVED RO -

14 RFE Wake Enable (RFE_WAKE_EN)

When set, remote wakeup mode is enabled and device is capable of

generating a wakeup from a non-errored receive frame that passes the

RFE’s filters.

This bit is automatically cleared at the completion of a resume sequence if

Resume Clears Remote Wakeup Enables (RES_CLR_WKP_EN) is set.

R/W 0b

13 Energy Efficient Ethernet TX Wake (EEE_TX_WAKE)

The MAC sets this bit upon the transmitter exiting the Low Power Idle state

due to the expiration of the time specified in EEE TX LPI Request Delay

Count Register (EEE_TX_LPI_REQUEST_DELAY_CNT).

This bit will not set if Energy Efficient Ethernet TX Wake Enable

(EEE_TX_WAKE_EN) is cleared.

This bit is automatically cleared at the completion of a resume sequence if

Resume Clears Remote Wakeup Status (RES_CLR_WKP_STS) is set.

This bit is held low if the Energy Efficient Ethernet Enable (EEEEN) bit in the

MAC Control Register (MAC_CR) is low.

R/WC 0b

12 Energy Efficient Ethernet TX Wake Enable (EEE_TX_WAKE_EN)

When set, remote wakeup is enabled upon the transmitter exiting the Low

Power Idle state.

This bit is automatically cleared at the completion of a resume sequence if

Resume Clears Remote Wakeup Enables (RES_CLR_WKP_EN) is set.

R/W 0b

11 Energy Efficient Ethernet RX Wake (EEE_RX_WAKE)

The MAC sets this bit upon the receiver exiting Low Power Idle state due to

the reception of wake signaling.

This bit will not set if Energy Efficient Ethernet RX Wake Enable

(EEE_RX_WAKE_EN) is cleared.

This bit is automatically cleared at the completion of a resume sequence if

Resume Clears Remote Wakeup Status (RES_CLR_WKP_STS) is set.

This bit is held low if the Energy Efficient Ethernet Enable (EEEEN) bit in the

MAC Control Register (MAC_CR) is low.

R/WC 0b

10 Energy Efficient Ethernet RX Wake Enable (EEE_RX_WAKE_EN)

When set, remote wakeup is enabled upon reception of wake signaling.

This bit is automatically cleared at the completion of a resume sequence if

Resume Clears Remote Wakeup Enables (RES_CLR_WKP_EN) is set.

R/W 0b

9RFE Wakeup Frame Received (RFE_WAKE_FR)

This bit is set upon reception of a non-errored frame that passes the RFE

filters.

This bit is automatically cleared at the completion of a resume sequence if

Resume Clears Remote Wakeup Status (RES_CLR_WKP_STS) is set.

R/WC 0b

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 197

LAN7850

8Store Wakeup Frame (STORE_WAKE)

When set, the frame associated with a wake event is stored in the FCT RX

FIFO. All subsequents frames received after the wake event which are not

corrupted and pass any applicable frame filters in the MAC and RFE are

stored in the FIFO.

When cleared, only frames received after the wake event are stored in the

RX FIFO. The frames must not be corrupted and pass any applicable frame

filters in the MAC and RFE.

Note: It is possible that the wakeup source was not a frame. In that case

all subsequent received frames are stored in the FIFO.

Note: This bit only has meaning when SUSPEND3 is used. For other

suspend modes this bit shall have no affect.

R/W 0b

7Perfect DA Frame Received (PFDA_FR)

The MAC sets this bit upon receiving a valid frame with a destination

address that matches the physical address.

This bit is automatically cleared at the completion of a resume sequence if

Resume Clears Remote Wakeup Status (RES_CLR_WKP_STS) is set.

R/WC 0b

6Remote Wakeup Frame Received (WUFR)

The MAC sets this bit upon receiving a valid remote Wakeup Frame.

This bit is automatically cleared at the completion of a resume sequence if

Resume Clears Remote Wakeup Status (RES_CLR_WKP_STS) is set.

R/WC 0b

5Magic Packet Received (MPR)

The MAC sets this bit upon receiving a valid Magic Packet.

This bit is automatically cleared at the completion of a resume sequence if

Resume Clears Remote Wakeup Status (RES_CLR_WKP_STS) is set.

R/WC 0b

4Broadcast Frame Received (BCAST_FR)

The MAC Sets this bit upon receiving a valid broadcast frame.

This bit is automatically cleared at the completion of a resume sequence if

Resume Clears Remote Wakeup Status (RES_CLR_WKP_STS) is set.

R/WC 0b

3Perfect DA Wakeup Enable (PFDA_EN)

When set, remote wakeup mode is enabled and the MAC is capable of

waking up on receipt of a frame with a destination address that matches the

physical address of the device. The physical address is stored in the MAC

Receive Address High Register (RX_ADDRH) and MAC Receiver Address

Low Register (RX_ADDRL).

This bit is automatically cleared at the completion of a resume sequence if

Resume Clears Remote Wakeup Enables (RES_CLR_WKP_EN) is set.

R/W 0b

2Wakeup Frame Enable (WUEN)

When set, remote wakeup mode is enabled and the MAC is capable of

detecting Wakeup Frames as programmed in the Wakeup Frame Filter.

This bit is automatically cleared at the completion of a resume sequence if

Resume Clears Remote Wakeup Enables (RES_CLR_WKP_EN) is set.

R/W 0b

1Magic Packet Enable (MPEN)

When set, Magic Packet wakeup mode is enabled.

This bit is automatically cleared at the completion of a resume sequence if

Resume Clears Remote Wakeup Enables (RES_CLR_WKP_EN) is set.

R/W 0b

BITS DESCRIPTION TYPE DEFAULT

LAN7850

DS00001993D-page 198  2015 - 2017 Microchip Technology Inc.

15.1.52 WAKEUP SOURCE REGISTER (WK_SRC)

This register indicates the source of the wakeup event that resulted in the device issuing wakeup signaling. Any wake

events that occurred while the device was being placed into the SUSPENDx state are ignored. Additionally, any wake

events that occur after the device has commenced the process of waking up are likewise ignored.

It is possible for a received wakeup packet to match several of the conditions listed in this CSR. In that case all matching

bits for that packet shall be set.

The status fields in this CSR are not cleared until explicitly done so by SW.

0Broadcast Wakeup Enable (BCAST_EN)

When set, remote wakeup mode is enabled and the MAC is capable of

waking up from a broadcast frame.

This bit is automatically cleared at the completion of a resume sequence if

Resume Clears Remote Wakeup Enables (RES_CLR_WKP_EN) is set.

R/W 0b

Offset: 144h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:20 GPIO [11:0] (GPIOx_INT_WK)

These bits assert from a GPIO wake event that results in the device issuing

wakeup signaling.

R/WAC 000h

19:17 RESERVED RO -

16 IPv6 TCP SYN Packet Received (IPV6_TCPSYN_RCD_WK)

The MAC sets this bit upon receiving a valid IPv6 TCP SYN packet that

results in the device issuing wakeup signaling.

R/WAC 0b

15 IPv4 TCP SYN Packet Received (IPV4_TCPSYN_RCD_WK)

The MAC sets this bit upon receiving a valid IPv4 TCP SYN packet that

results in the device issuing wakeup signaling.

R/WAC 0b

14 Energy Efficient Ethernet TX Wake (EEE_TX_WK)

The MAC sets this bit upon the transmitter exiting the Low Power Idle state

due to the expiration of the time specified in EEE TX LPI Request Delay

Count Register (EEE_TX_LPI_REQUEST_DELAY_CNT).

This bit will not set if Energy Efficient Ethernet TX Wake Enable

(EEE_TX_WAKE_EN) is cleared.

This bit is held low if the Energy Efficient Ethernet Enable (EEEEN) bit in the

MAC Control Register (MAC_CR) is low.

R/WAC 0b

13 Energy Efficient Ethernet RX Wake (EEE_RX_WK)

The MAC sets this bit upon the receiver exiting Low Power Idle state due to

the reception of wake signaling.

This bit will not set if Energy Efficient Ethernet RX Wake Enable

(EEE_RX_WAKE_EN) is cleared.

This bit is held low if the Energy Efficient Ethernet Enable (EEEEN) bit in the

MAC Control Register (MAC_CR) is low.

R/WAC 0b

BITS DESCRIPTION TYPE DEFAULT

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 199

LAN7850

12 RFE Wakeup Frame Received (RFE_FR_WK)

This bit is set bit upon reception of a non-errored frame that passes the

RFE’s filters and results in the device issuing wakeup signaling.

R/WAC 0b

11 Perfect DA Frame Received (PFDA_FR_WK)

The MAC sets this bit upon receiving a valid frame with a destination

address that matches the physical address that results in the device issuing

wakeup signaling.

R/WAC 0b

10 Magic Packet Received (MP_FR_WK)

The MAC sets this bit upon receiving a valid Magic Packet that results in the

device issuing wakeup signaling.

R/WAC 0b

9Broadcast Frame Received (BCAST_FR_WK)

The MAC Sets this bit upon receiving a valid broadcast frame that results in

the device issuing wakeup signaling.

R/WAC 0b

8Remote Wakeup Frame Received (WU_FR_WK)

The MAC sets this bit upon receiving a valid remote Wakeup Frame that

results in the device issuing wakeup signaling.

R/WAC 0b

7:5 RESERVED RO -

4:0 Remote Wakeup Frame Match (WUFF_MATCH)

This field indicates which wakeup frame filter caused the wake up event. The

contents of this field are only valid when Remote Wakeup Frame Received

(WU_FR_WK) is set.

R/WAC 0b

BITS DESCRIPTION TYPE DEFAULT

LAN7850

DS00001993D-page 200  2015 - 2017 Microchip Technology Inc.

15.1.53 WAKEUP FILTER X CONFIGURATION REGISTER (WUF_CFGX)

These CSRs enable the respective wakeup filter to be enabled. A total of 32 programmable filters are available in this

device where each filter can match a pattern up to 128 bytes in length.

Note 15-55 The default value for Wakeup Filter 0 is loaded from EEPROM, see Table 10-2, “EEPROM Format,”

on page 105. If no EEPROM is present, or if this information is not configured, then the default

depends on the OTP programmed value. It the OTP is not programmed then 0h is the default. A USB

Reset or Lite Reset (LRST) shall cause this field to be restored to the image value last loaded from

EEPROM, OTP, or to be set to 0h if neither is available.

Offset: 150h - 1CCh Size: 32 bits

Note: WUF_CFG0 supports Reset Protection (RST_PROTECT).

BITS DESCRIPTION TYPE DEFAULT

31 Filter Enable

0b: Filter disabled

1b: Filter enabled

R/W 0b

Note 15-55

30:26 RESERVED RO -

25:24 Filter Address Type

Defines the destination address type of the pattern (as specified for filter x

in the Wakeup Filter x Byte Mask Registers (WUF_MASKx) block).

00b: Pattern applies only to unicast frames.

10b: Pattern applies only to multicast frames.

X1b: Pattern applies to all frames.

R/W 00b

Note 15-55

23:16 Filter Pattern Offset

Specifies the offset of the first byte in the frame on which CRC checking

begins for Wakeup Frame recognition. Offset 0 is the first byte of the

incoming frame's destination address.

R/W 00h

Note 15-55

15:0 Filter CRC-16

Specifies the expected 16-bit CRC value for the filter that should be obtained

by using the pattern offset and the byte mask programmed for the filter. This

value is compared against the CRC calculated on the incoming frame, and

a match indicates the reception of a Wakeup Frame.

R/W 0000h

Note 15-55

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 201

LAN7850

15.1.54 WAKEUP FILTER X BYTE MASK REGISTERS (WUF_MASKX)

Each of the 32 wakeup filters has a 128-bit byte mask. The 128-bit mask is accessed via 4 consecutive byte mask

(DWORD) registers. The DWORD offset required to access a particular portion of the mask is indicated in the following

table. The start offset of the least significant DWORD register for each 128-bit filter block is the first element in the range

indicated in the preceding table and in the register map, Table 15-2, “System Control and Status Registers Map,” on

page 141.

If bit j of the byte mask is set, the CRC machine processes byte pattern offset + j of the incoming frame. Otherwise, byte

pattern offset + j is ignored.

Offset: 200h - 3FCh Size: 128 bits

Note: WUF_MASK0 supports Reset Protection (RST_PROTECT).

DWORD

OFFSET BITS DESCRIPTION TYPE DEFAULT

00h 31:0 Filter x Byte Mask [31:0] R/W 0h

Note 15-55

01h 31:0 Filter x Byte Mask [63:32] R/W 0h

Note 15-55

02h 31:0 Filter x Byte Mask [95:64] R/W 0h

Note 15-55

03h 31:0 Filter x Byte Mask [127:96] R/W 0h

Note 15-55

LAN7850

DS00001993D-page 202  2015 - 2017 Microchip Technology Inc.

15.1.55 MAC ADDRESS PERFECT FILTER REGISTERS (ADDR_FILTX)

These registers specify the MAC addresses used for perfect filtering.

It is permissible to change the value of an entry at run time. However, the address valid bit must be cleared before doing

so. Otherwise an invalid value will temporarily be in the MAC address filter.

Offset: 400h - 504h Size: 32 bits

Note: The MAC address storage scheme matches that for the RX_ADDRH and RX_ADDRL registers, see

Table 15-4, "RX_ADDRL, RX_ADDRH Byte Ordering".

DWORD

OFFSET BITS DESCRIPTION TYPE DEFAULT

0h 31 Address Valid

When set, this bit indicates that the entry has valid data and is

used in the perfect filtering.

R/W 0h

0h 30 Address Type

When set, this bit indicates the address represents the MAC

source address. Otherwise this entry applies to the MAC

destination address.

R/W 0h

0h 29:16 RESERVED RO -

0h 15-0 Physical Address [47:32]

This field contains the upper 16 bits [47:32] of the physical

address of the device.

R/W 0h

1h 31:0 Physical Address [31:0]

This field contains the lower 32 bits [31:0] of the physical address

of the device.

R/W 0h

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 203

LAN7850

15.1.56 WAKEUP CONTROL AND STATUS REGISTER 2 (WUCSR2)

This register contains data pertaining to Windows 7 Power Management wake and off-load features.

Offset: 600h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31 Checksum Disable (CSUM_DISABLE)

When clear, the IP header checksum, TCP checksum, and FCS are

calculated and all must agree with the frame contents, in order for the frame

(ARP, TCP_SYN, or NS) to be considered for detection analysis.

When set, only the FCS is calculated and checked for ARP, TCP_SYN, and

NS frames. The IP header checksum, ICMP payload checksum, and TCP

checksum are not calculated, hence any mismatches are ignored.

R/W 0b

30:11 RESERVED RO -

10 Forward ARP Frames (FARP_FR)

Enables passing received ARP frames that target this device and were

processed by the ARP offload logic to the RX datapath interface.

0 = Sink received ARP frames.

1 = Pass received ARP frames to the RX datapath interface.

R/W 0b

9Forward NS Frames (FNS_FR)

Enables passing received NS frames that target this device and were

processed by the NS offload logic to the RX datapath interface.

0 = Sink received NS frames.

1 = Pass received NS frames to the RX datapath interface.

R/W 0b

8NA SA Select (NA_SA_SEL)

Used to select source for IPv6 SA in NA message.

When set, NSx IPv6 Destination Address Register

(NSx_IPV6_ADDR_DEST) value is used as the source.

When cleared, the Target Address in NS packet is used.

R/W 0b

7NS Packet Received (NS_RCD)

The MAC sets this bit upon receiving a valid NS packet.

R/WC 0b

6ARP Packet Received (ARP_RCD)

The MAC sets this bit upon receiving a valid ARP packet.

R/WC 0b

5IPv6 TCP SYN Packet Received (IPV6_TCPSYN_RCD)

The MAC sets this bit upon receiving a valid IPv6 TCP SYN packet.

This bit is automatically cleared at the completion of a resume sequence if

Resume Clears Remote Wakeup Status (RES_CLR_WKP_STS) is set.

R/WC 0b

4IPv4 TCP SYN Packet Received (IPV4_TCPSYN_RCD)

The MAC sets this bit upon receiving a valid IPv4 TCP SYN packet.

This bit is automatically cleared at the completion of a resume sequence if

Resume Clears Remote Wakeup Status (RES_CLR_WKP_STS) is set.

R/WC 0b

3NS Offload Enable (NS_OFFLOAD_EN)

When set, enables the response to Neighbor Solicitation packets.

R/W 0b

2ARP Offload Enable (ARP_OFFLOAD_EN)

When set, enables the response to ARP packets.

R/W 0b

LAN7850

DS00001993D-page 204  2015 - 2017 Microchip Technology Inc.

15.1.57 NSX IPV6 DESTINATION ADDRESS REGISTER (NSX_IPV6_ADDR_DEST)

Used in IPv6 NS header matching, each IPv6 destination address is 128-bits. The 128-bit address is accessed via 4

consecutive (DWORD) registers. The DWORD offset required to access a particular portion of the address is indicated

in the following table. The start offset of the least significant DWORD register for each 128-bit address block is the first

element in the range indicated in the preceding table and in the register map, Table 15-2, “System Control and Status

Registers Map,” on page 141.

These registers are used when NS Offload Enable (NS_OFFLOAD_EN) is set in the Wakeup Control and Status Reg-

ister 2 (WUCSR2). Received packets whose Ethernet destination address is the device’s MAC address, a multi-cast

address, or the broadcast address are processed as follows:

The headers of all IPv6 packets are checked to determine whether (for 0<=x<=1) NSx IPv6 Destination Address Reg-

ister (NSx_IPV6_ADDR_DEST) matches the destination address specified in the IPv6 header. In the event that the IPv6

header destination address is a solicited node multicast address (i.e. it has a prefix that matches FF02::1:FF00:0/104),

only the upper three bytes (NSx_IPv6_ADDR_DEST_3 [127:104]) are compared against the last 24 bits of the IPv6

header destination address.

Please refer to Section 8.5, "Neighbor Solicitation (NS) Offload," on page 83 for further information.

The ordering for transmission of an IPv6 address over Ethernet is illustrated in Table 15-5, "IPv6 Address Transmission

Byte Ordering".

1IPv6 TCP SYN Wake Enable (IPV6_TCPSYN_WAKE_EN)

When set, enables the wakeup on receiving an IPv6 TCP SYN packet.

This bit is automatically cleared at the completion of a resume sequence if

Resume Clears Remote Wakeup Enables (RES_CLR_WKP_EN) is set.

Note this is only a documentation change.

R/W 0b

0IPv4 TCP SYN Wake Enable (IPV4_TCPSYN_WAKE_EN)

When set, enables the wakeup on receiving an IPv4 TCP SYN packet.

This bit is automatically cleared at the completion of a resume sequence if

Resume Clears Remote Wakeup Enables (RES_CLR_WKP_EN) is set.

R/W 0b

Offset: 610h - 61Ch,

650h - 65Ch

Size: 32 bits

DWORD

OFFSET BITS DESCRIPTION TYPE DEFAULT

00h 31:0 NSx_IPv6_ADDR_DEST_0 [31:0] R/W 0000_0000h

01h 31:0 NSx_IPv6_ADDR_DEST_1 [63:32] R/W 0000_0000h

02h 31:0 NSx_IPv6_ADDR_DEST_2 [95:64] R/W 0000_0000h

03h 31:0 NSx_IPv6_ADDR_DEST_3 [127:96] R/W 0000_0000h

BITS DESCRIPTION TYPE DEFAULT

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 205

LAN7850

TABLE 15-5: IPV6 ADDRESS TRANSMISSION BYTE ORDERING

NSx_IPV6_ADDR_DEST_x IPv6 Address Order of Reception on Ethernet

NSx_IPv6_ADDR_DEST_3[31:24] [127:120] 1st

NSx_IPv6_ADDR_DEST_3[23:16] [119:112] 2nd

NSx_IPv6_ADDR_DEST_3[15:8] [111:104] 3rd

NSx_IPv6_ADDR_DEST_3[7:0] [103:96] 4th

NSx_IPv6_ADDR_DEST_2[31:24] [95:88] 5th

NSx_IPv6_ADDR_DEST_2[23:16] [87:80] 6th

NSx_IPv6_ADDR_DEST_2[15:8] [79:72] 7th

NSx_IPv6_ADDR_DEST_2[7:0] [71:64] 8th

NSx_IPv6_ADDR_DEST_1[31:24] [63:56] 9th

NSx_IPv6_ADDR_DEST_1[23:16] [55:48] 10th

NSx_IPv6_ADDR_DEST_1[15:8] [47:40] 11th

NSx_IPv6_ADDR_DEST_1[7:0] [39:32] 12th

NSx_IPv6_ADDR_DEST_0[31:24] [31:24] 13th

NSx_IPv6_ADDR_DEST_0[23:16] [23:16] 14th

NSx_IPv6_ADDR_DEST_0[15:8] [15:8] 15th

NSx_IPv6_ADDR_DEST_0[7:0] [7:0] 16th

Note: This example applies to all other IPv6 address CSRs.

LAN7850

DS00001993D-page 206  2015 - 2017 Microchip Technology Inc.

15.1.58 NSX IPV6 SOURCE ADDRESS REGISTER (NSX_IPV6_ADDR_SRC)

Used in IPv6 NS header matching, each IPv6 source address is 128-bits. The 128-bit address is accessed via 4 con-

secutive (DWORD) registers. The DWORD offset required to access a particular portion of the address is indicated in

the following table. The start offset of the least significant DWORD register for each 128-bit address block is the first

element in the range indicated in the preceding table and in the register map, Table 15-2, “System Control and Status

Registers Map,” on page 141.

These registers are used when NS Offload Enable (NS_OFFLOAD_EN) is set in the Wakeup Control and Status Reg-

ister 2 (WUCSR2). Received packets whose destination address is the device’s MAC address, a multi-cast address, or

the broadcast address are processed as follows:

The headers of all IPv6 packets are checked to determine whether (for 0<=x<=1) NSx IPv6 Source Address Register

(NSx_IPV6_ADDR_SRC) matches the source address specified in the IPv6 header.

Please refer to Section 8.5, "Neighbor Solicitation (NS) Offload," on page 83 for further information.

The ordering for transmission of an IPv6 address over Ethernet is illustrated in Table 15-5, "IPv6 Address Transmission

Byte Ordering".

Offset: 620h - 62Ch,

660h - 66Ch

Size: 32 bits

Note: A value of all 0’s in all 4 DWORD registers equates to a wild-card, causes checking to be ignored, and

yields a match.

DWORD

OFFSET BITS DESCRIPTION TYPE DEFAULT

00h 31:0 NSx_IPv6_ADDR_SRC_0 [31:0] R/W 0000_0000h

01h 31:0 NSx_IPv6_ADDR_SRC_1 [63:32] R/W 0000_0000h

02h 31:0 NSx_IPv6_ADDR_SRC_2 [95:64] R/W 0000_0000h

03h 31:0 NSx_IPv6_ADDR_SRC_3 [127:96] R/W 0000_0000h

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 207

LAN7850

15.1.59 NSX ICMPV6 ADDRESS 0 REGISTER (NSX_ICMPV6_ADDR0)

Used in ICMPv6 NS target address matching. Each address is 128-bits and is accessed via 4 consecutive (DWORD)

registers. The DWORD offset required to access a particular portion of the address is indicated in the following table.

The start offset of the least significant DWORD register for each 128-bit address block is the first element in the range

indicated in the preceding table and in the register map, Table 15-2, “System Control and Status Registers Map,” on

page 141.

NS offload is enabled in the Wakeup Control and Status Register 2 (WUCSR2).

The target address specified in the NS request is compared to the values contained in the NSx ICMPv6 Address 0 Reg-

ister (NSx_ICMPV6_ADDR0) (these registers) and the corresponding NSx ICMPv6 Address 1 Register (NSx_IC-

MPV6_ADDR1), for all x where a match previously occurred in the IPv6 header. Please refer to Section 8.5, "Neighbor

Solicitation (NS) Offload," on page 83 for further information.

The ordering for transmission of an IPv6 address over Ethernet is illustrated in Table 15-5, "IPv6 Address Transmission

Byte Ordering".

Offset: 630h - 63Ch,

670h - 67Ch

Size: 32 bits

Note: A value of all 0’s in all 4 DWORD registers disables the comparison with this field. No match is yielded.

DWORD

OFFSET BITS DESCRIPTION TYPE DEFAULT

00h 31:0 NSx_ICMPV6_ADDR0_0 [31:0] R/W 0000_0000h

01h 31:0 NSx_ICMPV6_ADDR0_1 [63:32] R/W 0000_0000h

02h 31:0 NSx_ICMPV6_ADDR0_2 [95:64] R/W 0000_0000h

03h 31:0 NSx_ICMPV6_ADDR0_3 [127:96] R/W 0000_0000h

LAN7850

DS00001993D-page 208  2015 - 2017 Microchip Technology Inc.

15.1.60 NSX ICMPV6 ADDRESS 1 REGISTER (NSX_ICMPV6_ADDR1)

See NSx ICMPv6 Address 0 Register (NSx_ICMPV6_ADDR0) for a description of the usage of this register.

Please refer to Section 8.5, "Neighbor Solicitation (NS) Offload," on page 83 for further information.

The ordering for transmission of an IPv6 address over Ethernet is illustrated in Table 15-5, "IPv6 Address Transmission

Byte Ordering".

15.1.61 SYN IPV4 SOURCE ADDRESS REGISTER (SYN_IPV4_ADDR_SRC)

This register is utilized when IPv4 TCP SYN Wake Enable (IPV4_TCPSYN_WAKE_EN) is set in the Wakeup Control

and Status Register 2 (WUCSR2) and the device is in the SUSPEND0 or SUSPEND3 state. It holds the source address

to be compared to that of received IPv4 headers prefixing TCP packets whose SYN bit is asserted.

IPv4 frames whose destination address is the device’s MAC address, a multi-cast address, or the broadcast address

are processed as follows:

A check is made for a TCP protocol match within the IPv4 header. Valid TCP packets whose SYN bit is asserted, having

an IPv4 header whose source address and destination address match those specified in the SYN IPv4 Source Address

whose source port and destination port match those specified by the SYN IPv4 TCP Ports Register (SYN-

_IPV4_TCP_PORTS), will cause a wakeup.

Please refer to Section 8.3.3.1, "IPv4 TCP SYN Detection," on page 81 for further information.

Offset: 640h - 64Ch,

680h - 68Ch

Size: 32 bits

Note: A value of all 0’s in all 4 DWORD registers disables the comparison with this field. No match is yielded.

DWORD

OFFSET BITS DESCRIPTION TYPE DEFAULT

00h 31:0 NSx_ICMPV6_ADDR1_0 [31:0] R/W 0000_0000h

01h 31:0 NSx_ICMPV6_ADDR1_1 [63:32] R/W 0000_0000h

02h 31:0 NSx_ICMPV6_ADDR1_2 [95:64] R/W 0000_0000h

03h 31:0 NSx_ICMPV6_ADDR1_3 [127:96] R/W 0000_0000h

Offset: 690h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:0 SYN IPv4 Source Address [31:0]

Used in IPv4 header matching for TCP SYN packets.

Note: A value of all 0’s equates to a wild-card, causes checking to be

ignored, and yields a match.

R/W 0000_0000h

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 209

LAN7850

The ordering for transmission of anIPv4 address over Ethernet is illustrated in Table 15-6, "IPv4 Address Transmission

Byte Ordering".

This example applies to all other IPv4 address CSRs.

15.1.62 SYN IPV4 DESTINATION ADDRESS REGISTER (SYN_IPV4_ADDR_DEST)

This register is utilized when IPv4 TCP SYN Wake Enable (IPV4_TCPSYN_WAKE_EN) is set in the Wakeup Control

and Status Register 2 (WUCSR2) and the device is in the SUSPEND0 or SUPSEND3 state. It holds the destination

address to be compared to that of received IPv4 headers prefixing TCP packets whose SYN bit is asserted.

IPv4 frames whose destination address is the device’s MAC address, a multi-cast address, or the broadcast address

are processed as follows:

A check is made for a TCP protocol match within the IPv4 header. Valid TCP packets whose SYN bit is asserted, having

an IPv4 header whose source address and destination address match those specified in the SYN IPv4 Source Address

whose source port and destination port match those specified by SYN IPv4 TCP Ports Register (SYN-

_IPV4_TCP_PORTS), will cause a wakeup.

Please refer to Section 8.3.3.1, "IPv4 TCP SYN Detection," on page 81 for further information.

The ordering for transmission of anIPv4 address over Ethernet is illustrated in Table 15-6, "IPv4 Address Transmission

Byte Ordering".

TABLE 15-6: IPV4 ADDRESS TRANSMISSION BYTE ORDERING

SYN_IPV4_ADDR_SRC IPv4 Address Order of Reception on Ethernet

SYN_IPV4_ADDR_SRC[31:24] [31:24] 1st

SYN_IPV4_ADDR_SRC[23:16] [23:16] 2nd

SYN_IPV4_ADDR_SRC[15:8] [15:8] 3rd

SYN_IPV4_ADDR_SRC[7:0] [7:0] 4th

Offset: 694h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:0 SYN IPv4 Destination Address [31:0]

Used in IPv4 heading matching for TCP SYN packets.

Note: A value of all 0’s equates to a wild-card, causes checking to be

ignored, and yields a match.

R/W 0000_0000h

LAN7850

DS00001993D-page 210  2015 - 2017 Microchip Technology Inc.

15.1.63 SYN IPV4 TCP PORTS REGISTER (SYN_IPV4_TCP_PORTS)

This register is utilized when IPv4 TCP SYN Wake Enable (IPV4_TCPSYN_WAKE_EN) is set in the Wakeup Control

and Status Register 2 (WUCSR2) and the device is in the SUSPEND0 or SUPSEND3 state. It holds the source and

destination ports to be compared to that of received TCP packets whose SYN bit is asserted that are prefixed by a IPv4

header.

IPv4 frames whose destination address is the device’s MAC address, a multi-cast address, or the broadcast address

are processed as follows:

A check is made for a TCP protocol match within the IPv4 header. Valid TCP packets whose SYN bit is asserted, having

an IPv4 header whose source address and destination address match those specified in the SYN IPv4 Source Address

whose source port and destination port match those specified by the SYN IPv4 TCP Ports Register (SYN-

_IPV4_TCP_PORTS), will cause a wakeup.

Please refer to Section 8.3.3.1, "IPv4 TCP SYN Detection," on page 81 for further information.

Offset: 698h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:16 Destination Port (IPV4_DEST_PORT)

Used in IPv4 TCP port matching for TCP SYN packets.

Note: A value of all 0’s equates to a wild-card, causes checking to be

ignored, and yields a match.

R/W 0000h

15:0 Source Port (IPV4_SRC_PORT)

Used in IPv4 TCP port matching for TCP SYN packets.

Note: A value of all 0’s equates to a wild-card, causes checking to be

ignored, and yields a match.

R/W 0000h

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 211

LAN7850

15.1.64 SYN IPV6 SOURCE ADDRESS REGISTER (SYN_IPV6_ADDR_SRC)

This register is used in IPv6 header matching for TCP SYN packets and is 128-bits. The address is accessed via 4 con-

secutive (DWORD) registers. The DWORD offset required to access a particular portion of the address is indicated in

the following table. The start offset of the least significant DWORD register for the 128-bit address block is the first ele-

ment in the range indicated in the preceding table and in the register map, Table 15-2, “System Control and Status Reg-

isters Map,” on page 141.

This register is utilized when IPv6 TCP SYN Wake Enable (IPV6_TCPSYN_WAKE_EN) is set in the Wakeup Control

and Status Register 2 (WUCSR2) and the device is in the SUSPEND0 state. It holds the source address to be compared

to that of the IPv6 header (or an extension header) prefixing a TCP packet whose SYN bit is asserted. The IPv6 frame

must have previously passed a check to ensure that its destination address is the device’s MAC address, a multi-cast

address, or the broadcast address.

Valid TCP packets whose SYN bit is asserted, having an IPv6 header whose source address and destination address

match those specified by the SYN IPv6 Source Address Register (SYN_IPV6_ADDR_SRC) and the SYN IPv6 Desti-

nation Address Register (SYN_IPV6_ADDR_DEST), and whose source port and destination port match those specified

by the SYN IPv6 TCP Ports Register (SYN_IPV6_TCP_PORTS), will cause a wakeup.

Please refer to Section 8.3.4, "IPv6 TCP SYN Detection," on page 82 for further information.

The ordering for transmission of the IPv6 address over Ethernet is illustrated in Table 15-5, "IPv6 Address Transmission

Byte Ordering".

Offset: 69Ch - 6A8h Size: 32 bits

Note: A value of all 0’s in all 4 DWORD registers equates to a wild-card, causes checking to be ignored, and

yields a match.

DWORD

OFFSET BITS DESCRIPTION TYPE DEFAULT

00h 31:0 SYN_IPV6_ADDR_SRC_0 [31:0] R/W 0000_0000h

01h 31:0 SYN_IPV6_ADDR_SRC_1 [63:32] R/W 0000_0000h

02h 31:0 SYN_IPV6_ADDR_SRC_2 [95:64] R/W 0000_0000h

03h 31:0 SYN_IPV6_ADDR_SRC_3 [127:96] R/W 0000_0000h

LAN7850

DS00001993D-page 212  2015 - 2017 Microchip Technology Inc.

15.1.65 SYN IPV6 DESTINATION ADDRESS REGISTER (SYN_IPV6_ADDR_DEST)

This register is used in IPv6 header matching for TCP SYN packets and is 128-bits. The address is accessed via 4 con-

secutive (DWORD) registers. The DWORD offset required to access a particular portion of the address is indicated in

the following table. The start offset of the least significant DWORD register for the 128-bit address block is the first ele-

ment in the range indicated in the preceding table and in the register map, Table 15-2, “System Control and Status Reg-

isters Map,” on page 141.

This register is utilized when IPv6 TCP SYN Wake Enable (IPV6_TCPSYN_WAKE_EN) is set in the Wakeup Control

and Status Register 2 (WUCSR2) and the device is in the SUSPEND0 or SUSPEND3 state. It holds the destination

address to be compared to that of the IPv6 header (or an extension header) prefixing a TCP packet whose SYN bit is

asserted. The IPv6 frame must have previously passed a check to ensure that its destination address is the device’s

MAC address, a multi-cast address, or the broadcast address.

Valid TCP packets whose SYN bit is asserted, having an IPv6 header whose source address and destination address

match those specified by the SYN IPv6 Source Address Register (SYN_IPV6_ADDR_SRC) and the SYN IPv6 Desti-

nation Address Register (SYN_IPV6_ADDR_DEST), and whose source port and destination port match those specified

by the SYN IPv6 TCP Ports Register (SYN_IPV6_TCP_PORTS), will cause a wakeup.

Please refer to Section 8.3.4, "IPv6 TCP SYN Detection," on page 82 for further information.

The ordering for transmission of the IPv6 address over Ethernet is illustrated in Table 15-5, "IPv6 Address Transmission

Byte Ordering".

Offset: 6ACh - 6B8h Size: 32 bits

Note: A value of all 0’s in all 4 DWORD registers equates to a wild-card, causes checking to be ignored, and

yields a match.

DWORD

OFFSET BITS DESCRIPTION TYPE DEFAULT

00h 31:0 SYN_IPV6_ADDR_DEST_0 [31:0] R/W 0000_0000h

01h 31:0 SYN_IPV6_ADDR_DEST_1 [63:32] R/W 0000_0000h

02h 31:0 SYN_IPV6_ADDR_DEST_2 [95:64] R/W 0000_0000h

03h 31:0 SYN_IPV6_ADDR_DEST_3 [127:96] R/W 0000_0000h

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 213

LAN7850

15.1.66 SYN IPV6 TCP PORTS REGISTER (SYN_IPV6_TCP_PORTS)

This register is utilized when IPv6 TCP SYN Wake Enable (IPV6_TCPSYN_WAKE_EN) is set in the Wakeup Control

and Status Register 2 (WUCSR2) and the device is in the SUSPEND0 state. It holds the source and destination ports

to be compared to that of received TCP packets whose SYN bit is asserted that are prefixed by a IPv6 header or exten-

sion header.

IPv6 frames whose destination address is the device’s MAC address, a multi-cast address, or the broadcast address

are processed as follows:

A check is made for a TCP protocol match within the IPv6 header. Valid TCP packets whose SYN bit is asserted, having

an IPv6 header whose source address and destination address match those specified in the SYN IPv6 Source Address

whose source port and destination port match those specified by the SYN IPv6 TCP Ports Register (SYN-

_IPV6_TCP_PORTS), will cause a wakeup.

Please refer to Section 8.3.4, "IPv6 TCP SYN Detection," on page 82 for further information.

Offset: 6BCh Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:16 Destination Port (IPV6_DEST_PORT)

Used in IPv6 TCP port matching for TCP SYN packets.

Note: A value of all 0’s equates to a wild-card, causes checking to be

ignored, and yields a match.

R/W 0000h

15:0 Source Port (IPV6_SRC_PORT)

Used in IPv6 TCP port matching for TCP SYN packets.

Note: A value of all 0’s equates to a wild-card, causes checking to be

ignored, and yields a match.

R/W 0000h

LAN7850

DS00001993D-page 214  2015 - 2017 Microchip Technology Inc.

15.1.67 ARP SENDER PROTOCOL ADDRESS REGISTER (ARP_SPA)

This register is utilized when ARP offload is enabled in the Wakeup Control and Status Register 2 (WUCSR2). The frame

type for all received Ethernet frames is examined and those of type 0806h (ARP frames) are checked to ensure that the

MAC destination address matches the device’s MAC address or is the broadcast address. If the packet passes these

tests, the contents of this register is compared to the SPA field of the ARP message and the contents of the ARP Target

Protocol Address Register (ARP_TPA) is compared to the TPA field of the ARP message. If the contents of both regis-

ters match the contents of the message and no errors occurred on the frame, then the MAC TX is signaled to transmit

an ARP response frame to the sender.

Please refer to Section 8.6, "ARP Offload," on page 85 for further information.

15.1.68 ARP TARGET PROTOCOL ADDRESS REGISTER (ARP_TPA)

This register is utilized when ARP offload is enabled in the Wakeup Control and Status Register 2 (WUCSR2). The frame

type for all received Ethernet frames is examined and those of type 0806h (ARP frames) are checked to ensure that the

MAC destination address matches the device’s MAC address or is the broadcast address. If the packet passes these

tests, the contents of the ARP Sender Protocol Address Register (ARP_SPA) is compared to the SPA field of the ARP

message and the contents of the this register is compared to the TPA field of the ARP message. If the contents of both

registers match the contents of the message and no errors occurred on the frame, then the MAC TX is signaled to trans-

mit an ARP response frame to the sender.

Please refer to Section 8.6, "ARP Offload," on page 85 for further information.

Offset: 6C0h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:0 ARP_SPA [31:0]

Used in ARP matching.

Note: A value of all 0’s = wild-card, causes checking to be ignored, and

yields a match.

R/W 0000h

Note: Note: The ordering for transmission of anIPv4 address over Ethernet is illustrated in Table 15-6, "IPv4

Address Transmission Byte Ordering".

Offset: 6C4h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:0 ARP_TPA [31:0]

Used in ARP matching.

Note: A value of all 0’s = wild-card, causes checking to be ignored, and

yields a match.

R/W 0000h

Note: Note: The ordering for transmission of anIPv4 address over Ethernet is illustrated in Table 15-6, "IPv4

Address Transmission Byte Ordering".

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 215

LAN7850

15.1.69 PHY DEVICE IDENTIFIER (PHY_DEV_ID)

This register defines the integrated Ethernet PHY’s OUI, Model Number, and Device Revision Number.

Offset: 700h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:28 Revision Number RO 0h

27:22 Model Number RO 13h

21:0 OUI

Organizationally-Unique Identifier. Assigned to the 3rd through 24th bit of the

OUI.

RO 00_01F0h

LAN7850

DS00001993D-page 216  2015 - 2017 Microchip Technology Inc.

15.2 USB PHY Control and Status Registers

Note: RESERVED address space in the USB PHY Control and Status Registers Map must not be written

under any circumstances. Failure to heed this warning may result in untoward operation and unex-

pected results.

TABLE 15-7: USB PHY CONTROL AND STATUS REGISTERS MAP

OFFSET

(1200h+offset) REGISTER NAME

000h Common Block Test Register (COM_TEST)

004h – 0C0h Reserved

0C4h USB 2.0 AFE Test Register (USB2_TEST)

0C8h USB 2.0 AFE Upstream Control Register (USB2_AFE_CTRL)

0CCh – 13Ch Reserved

140h HSIC Enable Register (HSIC_EN)

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 217

LAN7850

15.2.1 COMMON BLOCK TEST REGISTER (COM_TEST)

Offset: 000h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31 Clock Disable (CLOCK_DISABLE)

When set, the clocks to the common block register will be gated off.

R/W 0b

30:25 RESERVED RO -

24 Common Block Test Register Select (COM_BLK_SEL)

Common Block Test register select.

0: Passes functional signals to the Common block

1: Passes test signals to the Common block

R/W 0b

23 Common XTAL Gain Select (COM_TST_XTAL_GAIN)

0: XTAL drive amplitude limited to 0.9V

1: XTAL drive amplitude increased to 1V

R/W 0b

22:20 RESERVED RO -

19 Input Reference Frequency Select for all PLLs (COM_REF_FREQ)

0: 25 MHz - POR

1: 24 MHz

Note: Gigabit Ethernet PHY requires 25 MHz. 24 MHz is not a valid

operational setting.

R/W 0b

18 1.2V POR (COM_V12CR_RDY)

POR output from the core 1.2V supply. Active high when core supply is

above 0.85V. Signal is gated off by internal 3V POR signal (active high

threshold of 2.7V).

RO 0b

17 Enable Link Power Management Mode (COM_PLL_LPM_MODE)

Enables fast startup of the USB2 PLL.

R/W Note 15-56

16 Enable USB 2.0 PLL (COM_PLL_EN) R/W 1b

15 Common Suspend (COM_SUSPENDB)

Powers down the common circuitry (Biasing and PLL). When asserted, this

signal overrides all local UTMI suspend signals and will power down all AFE

blocks connected to it. This signal is active low.

R/W 0b

14 XTAL Suspend (COM_XTAL_SUSPENDB)

When asserted, this signal will power down the XTAL block. The XTAL clock

can be kept running when SUSPEND_N is asserted for LPM. This signal is

active low.

R/W 0b

13 RESERVED RO -

LAN7850

DS00001993D-page 218  2015 - 2017 Microchip Technology Inc.

Note 15-56 The default value of this field is determined by the Enable Link Power Management Mode

(COM_PLL_LPM_MODE) bit in of Configuration Flags 0 within the EEPROM, if present. The field

chosen depends on whether the device is in HS or FS mode. If no EEPROM is present then the

value programmed in OTP is used. If OTP is not configured then 0b is the default. A USB Reset or

Lite Reset (LRST) will cause this field to be restored to the image value last loaded from EEPROM,

or OTP, or to be set to 0b if neither is present.

12 PLL Clock Usable (COM_CLK_USABLE)

0: Clocks not usable

1: Clocks are usable

RO 0b

11:10 RESERVED RO -

9AFE_RDY_TIM_DIS

When set disables the AFE ready timer.

R/W 0b

8:1 RESERVED RO -

0Clock gate bypass mode select (PHY_CLK_GATE_BYPASS)

0: Functional mode.

1: Forcibly puts all clock gating logic in the chip in bypass mode.

R/W 0b

BITS DESCRIPTION TYPE DEFAULT

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 219

LAN7850

15.2.2 USB 2.0 AFE TEST REGISTER (USB2_TEST)

Offset: 0C4h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:23 RESERVED RO -

22 FS/LS Driver Output Enable (USB2_FS_OEB)

Active low.

0: Driver enabled

1: Driver tri-stated

R/W 0b

21 FS/LS Positive Output Data (USB2_FS_VPO)

Drives data to the DP output.

R/W 0b

20 FS/LS Negative Output Data (USB2_FS_VMO)

Drives data to the DM output

R/W 0b

19 FS/LS Differential Receiver Output (USB2_FS_DATA) RO 0b

18:16 RESERVED RO -

15:14 HS Transmit Valid Mask (USB2_HS_TXVALID)

Indicates which bits of the AFE_HS_TXVALID[1:0] bus is valid.

00: No bits valid

01: LSB valid

10: Invalid combination

11: Both bits valid

R/W 00b

13:12 HS Transmit Data (USB2_HS_TXDATA)

Driver data is transmitted LSB first.

R/W 00b

11 HS Current Source Enable (USB2_HS_CS_EN)

0: Driver powered-down

1: Driver powered-up

This signal will be asserted active whenever the port is in Hi-Speed mode.

R/W 0b

10:8 HS Output Current (PHY_BOOST)

000b: Nominal 17.78mA

001b: Decrease by 5%

010b: Increase by 10%

011b: Increase by 5%

100b: Increase by 20%

101b: Increase by 15%

110b: Increase by 30%

111b: Increase by 25%

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W Note 15-57

7Rpu DP Termination Control (USB2_RPU_DP_EN)

Enable the 1.5 Kohm termination on DP when active.

R/W 0b

LAN7850

DS00001993D-page 220  2015 - 2017 Microchip Technology Inc.

Note 15-57 The default value of this field is determined by the value of the PHY Boost (CFG0_PHY_BOOST)

field in Configuration Flags 0 contained within the EEPROM, if present. If no EEPROM is present

then default depends on the OTP programmed value. It the OTP is not programmed then 000b is the

default. A USB Reset or Lite Reset (LRST) will cause this field to be restored to the image value last

loaded from EEPROM, or to be set to 000b if no EEPROM is present.

6Rpu DP Termination Control (USB2_RPU_DM_EN)

Enable the 1.5 Kohm termination on DP when active.

R/W 0b

5Rpd DP Termination Control (USB2_RPD_DP_EN)

Enable the 15 Kohm termination on DP when active.

R/W 0b

4Rpd DM Termination Control (USB2_RPD_DM_EN)

Enable the 15 Kohm termination on DM when active.

R/W 0b

3:2 RESERVED RO -

1HS Driver Active (USB2_HS_TXACTIVE)

Places the HS driver in low power mode when disabled (during IDLE).

0: Driver in low-power mode

1: Driver in active transmit mode (17.78 mA source active)

R/W 0b

0RESERVED RO -

BITS DESCRIPTION TYPE DEFAULT

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 221

LAN7850

15.2.3 USB 2.0 AFE UPSTREAM CONTROL REGISTER (USB2_AFE_CTRL)

Note 15-58 The default value of this field is determined by the value of the Squelch Threshold (CFG0_SQU_THR)

field of Configuration Flags 0 contained within the EEPROM, if present. If no EEPROM is present

then the value programmed in OTP is used. If OTP is not configured then 3’b000 is the default. A

USB Reset or Lite Reset (LRST) will cause this field to be restored to the image value last loaded

from EEPROM, or OTP, or to be set to 000b if neither is present.

Offset: 0C8h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:30 RESERVED RO -

29 HS Termination Control (USB2_HS_TERM_EN)

Enable the 45 Kohm termination on DP and DM when active.

R/W 0b

28 AFE High Speed Squelch (USB2_HS_SQUELCH_B)

Indicates when the HS oversampled data is valid. Active low.

0: Data valid

1: Data is invalid

RO 0b

27 AFE High Speed Disconnect (USB2_HS_DISC)

Indicates when the line is disconnected in HS mode. This signal should only

be strobed during HS EOP on the 32nd bit time.

0: Normal condition

1: Disconnect condition

RO 0b

26:24 Squelch Tune (USB2_SQU_TUNE)

000: Nominal 100mV Trip Point

001: Decrease by 12.5mV

010: Decrease by 25mV

011: Decrease by 37.5mV

100: Decrease by 50mV

101: Decrease by 62.5mV

110: Increase by 25mV

111: Increase by 12.5mV

Note: This field is protected by Reset Protection (RST_PROTECT).

R/W Note 15-58

23:0 RESERVED RO -

LAN7850

DS00001993D-page 222  2015 - 2017 Microchip Technology Inc.

15.2.4 HSIC ENABLE REGISTER (HSIC_EN)

Note 15-59 The default value of is 1b when the HSIC_SEL pin is tied to VDD. Otherwise the default value is 0b.

Note 15-60 The default value of this field is determined by the value of the HSIC 50ohm Driver Data and Strobe

Enable (HSIC_DS_EN50) field of Configuration Flags 0 contained within the EEPROM, if present. If

no EEPROM is present then the value programmed in OTP is used. If OTP is not configured then

0b is the default. A USB Reset or Lite Reset (LRST) will cause this field to be restored to the image

value last loaded from EEPROM, or OTP, or to be set to 0b if neither is present.

Note 15-61 The default value of this field is determined by the value of the HSIC Slew Tune Test Bit Data and

Strobe (HSIC_DS_SLEW_TUNE) field of Configuration Flags 0 contained within the EEPROM, if

present. If no EEPROM is present then the value programmed in OTP is used. If OTP is not

configured then 0b is the default. A USB Reset or Lite Reset (LRST) will cause this field to be

restored to the image value last loaded from EEPROM, or OTP, or to be set to 0b if neither is present.

Note 15-62 The default value of this field is determined by the value of the HSIC Pin Swap (HSIC_PIN_SWAP)

field of Configuration Flags 0 contained within the EEPROM, if present. If no EEPROM is present

then the value programmed in OTP is used. If OTP is not configured then 0b is the default. A USB

Reset or Lite Reset (LRST) will cause this field to be restored to the image value last loaded from

EEPROM, or OTP, or to be set to 0b if neither is present.

Offset: 140h Size: 32 bits

BITS DESCRIPTION TYPE DEFAULT

31:25 RESERVED RO -

24 HSIC Interface Enable (HSIC_ENABLE)

0: Port is in USB mode

1: Port is in HSIC mode.

R/W Note 15-59

23:19 RESERVED RO -

18 HSIC 50ohm Driver Data and Strobe Enable (HSIC_DS_EN50)

Selects the driver output impedance.

0: 40ohm driver

1: 50ohm driver.

R/W Note 15-60

17 HSIC Slew Tune Test Bit Data and Strobe (HSIC_DS_SLEW_TUNE)

Reduces transmit slew rate on Data/Strobe by 30%.

0: TX Slew boost disabled (Default)

1: TX Slew boosted by 30%

R/W Note 15-61

16 HSIC Pin Swap (HSIC_PIN_SWAP)

When set the HSIC Data and Strobe pins swap.

R/W Note 15-62

15:0 RESERVED RO -

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 223

LAN7850

15.3 Ethernet PHY Control and Status Registers

The Ethernet PHY registers are not memory mapped. These registers are accessed indirectly through the Ethernet

MAC via the MII Access Register (MII_ACCESS) and MII Data Register (MII_DATA). The Ethernet PHY provides access

to the following main categories of registers:

•Ethernet PHY Main Page Registers

•Ethernet PHY Extended Page 1 Registers

•Ethernet PHY Extended Page 2 Registers

Note: Access to the PHY register pages is controlled via the Ethernet PHY Extended Page Access Register.

When extended page 1 or 2 register access is enabled, reads and writes to registers 16 through 30 affect

the extended registers for the corresponding page instead of the main page registers in the IEEE-specified

Writing 0000h to the Ethernet PHY Extended Page Access Register restores main page register access.

Note: All unlisted register index values are not supported and should not be addressed.

TABLE 15-8: ETHERNET PHY MAIN PAGE REGISTERS

INDEX

(IN DECIMAL) REGISTER NAME

0Ethernet PHY Mode Control Register

1Ethernet PHY Mode Status Register

2Ethernet PHY Device Identifier 1 Register

3Ethernet PHY Device Identifier 2 Register

4Ethernet PHY Device Auto-Negotiation Advertisement Register

5Ethernet PHY Auto-Negotiation Link Partner Ability Register

6Ethernet PHY Auto-Negotiation Expansion Register

7Ethernet PHY Auto-Negotiation Next Page TX Register

8Ethernet PHY Auto-Negotiation Link Partner Next Page RX Register

9Ethernet PHY 1000BASE-T Control Register

10 Ethernet PHY 1000BASE-T Status Register

11-12 RESERVED

13 Ethernet PHY MMD Access Control Register

14 Ethernet PHY MMD Access Address/Data Register

15 Ethernet PHY 1000BASE-T Status Extension 1 Register

16 Ethernet PHY 100BASE-TX Status Extension Register

17 Ethernet PHY 1000BASE-T Status Extension 2 Register

18 Ethernet PHY Bypass Control Register

19 100BASE-TX/1000BASE-T Receive Error Counter Register

LAN7850

DS00001993D-page 224  2015 - 2017 Microchip Technology Inc.

20 100BASE-TX/1000BASE-T False Carrier Error Counter Register

21 10BASE-T/100BASE-TX/1000BASE-T Link Disconnect Counter Register

22 Ethernet PHY Extended 10BASE-T Control and Status Register

23 Ethernet PHY Extended PHY Control 1 Register

24 Ethernet PHY Extended PHY Control 2 Register

25 Ethernet PHY Interrupt Mask Register

26 Ethernet PHY Interrupt Status Register

27 RESERVED

28 Ethernet PHY Auxiliary Control and Status Register

29 Ethernet PHY LED Mode Select Register

30 Ethernet PHY LED Behavior Register

31 Ethernet PHY Extended Page Access Register

TABLE 15-8: ETHERNET PHY MAIN PAGE REGISTERS (CONTINUED)

INDEX

(IN DECIMAL) REGISTER NAME

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 225

LAN7850

15.3.1 ETHERNET PHY MAIN PAGE REGISTERS

This section details the Ethernet PHY main page register descriptions.

15.3.1.1 Ethernet PHY Mode Control Register

Note: Ethernet PHY main page registers 0 through 15 may be accessed on the following pages: Page 0, 1, 2.

The pages that a particular register is accessible on are also listed in the individual register description.

Access to the PHY register pages is controlled via the Ethernet PHY Extended Page Access Register.

Index (In Decimal):

Pages:

0,1,2

Size: 16 bits

BITS DESCRIPTION TYPE DEFAULT

15 PHY Soft Reset (RESET)

1 = PHY software reset. Bit is self-clearing.

R/W

14 Digital Loopback

0 = normal operation

1 = Digital loopback mode

R/W 0b

13 Speed Select[0]

Together with Speed Select[1], sets speed per the following table:

[Speed Select1][Speed Select0]

00 = 10Mbps

01 = 100Mbps

10 = 1000Mbps

11 = Reserved

Note: Ignored if the Auto-Negotiation Enable bit of this register is 1.

R/W 0b

12 Auto-Negotiation Enable

0 = disable auto-negotiate process

1 = enable auto-negotiate process (overrides the Speed Select[0], Speed

Select[1], and Duplex Mode bits of this register)

R/W 1b

11 Power Down

0 = normal operation

1 = General power down mode

Note: The Auto-Negotiation Enable must be cleared before setting the

Power Down bit.

R/W 0b

10 RESERVED RO -

9Restart Auto-Negotiate

0 = normal operation

1 = restart auto-negotiate process

Note: Bit is self-clearing.

R/W

8Duplex Mode

0 = half duplex

1 = full duplex

Note: Ignored if the Auto-Negotiation Enable bit of this register is 1.

R/W 0b

7RESERVED RO -

6Speed Select[1]

See description for Speed Select[0] for details.

RO 1b

5:0 RESERVED RO -

LAN7850

DS00001993D-page 226  2015 - 2017 Microchip Technology Inc.

15.3.1.2 Ethernet PHY Mode Status Register

Index (In Decimal):

Pages:

0,1,2

Size: 16 bits

BITS DESCRIPTION TYPE DEFAULT

15 100BASE-T4

0 = no T4 ability

1 = T4 able

RO 0b

14 100BASE-TX Full Duplex

0 = no TX full duplex ability

1 = TX with full duplex

RO 1b

13 100BASE-TX Half Duplex

0 = no TX half duplex ability

1 = TX with half duplex

RO 1b

12 10BASE-T Full Duplex

0 = no 10Mbps with full duplex ability

1 = 10Mbps with full duplex

RO 1b

11 10BASE-T Half Duplex

0 = no 10Mbps with half duplex ability

1 = 10Mbps with half duplex

RO 1b

10 100BASE-T2 Full Duplex

0 = PHY not able to perform full duplex 100BASE-T2

1 = PHY able to perform full duplex 100BASE-T2

RO 0b

9100BASE-T2 Half Duplex

0 = PHY not able to perform half duplex 100BASE-T2

1 = PHY able to perform half duplex 100BASE-T2

RO 0b

8Extended Status

0 = no extended status information in register 15

1 = extended status information in register 15

RO 1b

7:6 RESERVED RO -

5Auto-Negotiate Complete

0 = auto-negotiate process not completed

1 = auto-negotiate process completed

RO 0b

4Remote Fault

0 = no remote fault

1 = remote fault condition detected

RO 0b

3Auto-Negotiate Ability

0 = unable to perform auto-negotiation function

1 = able to perform auto-negotiation function

RO 1b

2Link Status

0 = link is down

1 = link is up

RO/LL 0b

1Jabber Detect

0 = no 10BASE-T jabber condition detected

1 = 10BASE-T jabber condition detected

RO 0b

0Extended Capabilities

0 = does not support extended capabilities registers

1 = supports extended capabilities registers

RO 1b

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 227

LAN7850

15.3.1.3 Ethernet PHY Device Identifier 1 Register

15.3.1.4 Ethernet PHY Device Identifier 2 Register

Note 15-63 The default value of this field will vary depending on the silicon revision number.

Index (In Decimal):

Pages:

0,1,2

Size: 16 bits

BITS DESCRIPTION TYPE DEFAULT

15:0 PHY ID Number

Assigned to the 3rd through 18th bits of the Organizationally Unique

Identifier (OUI), respectively.

RO 0007h

Index (In Decimal):

Pages:

0,1,2

Size: 16 bits

BITS DESCRIPTION TYPE DEFAULT

15:10 PHY ID Number

Assigned to the 19th through 24th bits of the OUI.

RO 110000b

9:4 Model Number

Six-bit manufacturer’s model number.

R/W 010011b

3:0 Revision Number

Four-bit manufacturer’s revision number.

R/W Note 15-63

LAN7850

DS00001993D-page 228  2015 - 2017 Microchip Technology Inc.

15.3.1.5 Ethernet PHY Device Auto-Negotiation Advertisement Register

Index (In Decimal):

Pages:

0,1,2

Size: 16 bits

BITS DESCRIPTION TYPE DEFAULT

15 Next Page

0 = no next page ability

1 = next page capable

Note:

R/W 0b

14 RESERVED RO -

13 Remote Fault

0 = no remote fault

1 = remote fault detected

R/W 0b

12 RESERVED RO -

11 Asymmetric Pause

0 = Asymmetrical pause direction is not advertised

1 = Asymmetrical pause direction is advertised

R/W 0b

10 Pause Operation

0 = Pause operation is not advertised

1 = Pause operation is advertised

R/W 0b

9RESERVED RO -

8100BASE-TX Full Duplex

0 = no TX full duplex ability

1 = TX with full duplex

R/W 1b

7100BASE-TX

0 = no TX ability

1 = TX able

R/W 1b

610BASE-T Full Duplex

0 = no 10Mbps with full duplex ability

1 = 10Mbps with full duplex

R/W 1b

510BASE-T

0 = no 10Mbps ability

1 = 10Mbps able

R/W 1b

4:0 Selector Field

00001 = IEEE 802.3

R/W 00001b

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 229

LAN7850

15.3.1.6 Ethernet PHY Auto-Negotiation Link Partner Ability Register

Index (In Decimal):

Pages:

0,1,2

Size: 16 bits

BITS DESCRIPTION TYPE DEFAULT

15 Link Partner Next Page

0 = no next page ability

1 = next page capable

RO 0b

14 Link Partner Acknowledge

0 = link code word not yet received

1 = link code word received from partner

RO 0b

13 Link Partner Remote Fault

0 = no remote fault

1 = remote fault detected

RO 0b

12 RESERVED RO -

11 Link Partner Asymmetric Pause

0 = Asymmetrical pause direction is not advertised

1 = Asymmetrical pause direction is advertised

R/W 0b

10 Link Partner Pause Operation

0 = Symmetrical pause operation is not advertised

1 = Symmetrical pause operation is advertised

RO 0b

9Link Partner 100BASE-T4

0 = no T4 ability

1 = T4 able

Note: This PHY does not support T4 ability.

RO 0b

8Link Partner 100BASE-TX Full Duplex

0 = no TX full duplex ability

1 = TX with full duplex

RO 0b

7Link Partner 100BASE-TX Half Duplex

0 = no TX half duplex ability

1 = TX half duplex able

RO 0b

6Link Partner 10BASE-T Full Duplex

0 = no 10Mbps with full duplex ability

1 = 10Mbps with full duplex

RO 0b

5Link Partner 10BASE-T Half Duplex

0 = no 10Mbps half duplex ability

1 = 10Mbps half duplex able

RO 0b

4:0 Link Partner Selector Field

00001 = IEEE 802.3

RO 00000b

LAN7850

DS00001993D-page 230  2015 - 2017 Microchip Technology Inc.

15.3.1.7 Ethernet PHY Auto-Negotiation Expansion Register

Index (In Decimal):

Pages:

0,1,2

Size: 16 bits

BITS DESCRIPTION TYPE DEFAULT

15:5 RESERVED RO -

4Parallel Detection Fault

0 = no fault detected by parallel detection logic

1 = fault detected by parallel detection logic

RO/LH 0b

3Link Partner Next Page Able

0 = link partner does not have next page ability

1 = link partner has next page ability

RO 0b

2Next Page Able

0 = local device does not have next page ability

1 = local device has next page ability

RO 1b

1Page Received

0 = new page not yet received

1 = new page received

RO/LH 0b

0Link Partner Auto-Negotiation Able

0 = link partner does not have auto-negotiation ability

1 = link partner has auto-negotiation ability

RO 0b

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 231

LAN7850

15.3.1.8 Ethernet PHY Auto-Negotiation Next Page TX Register

Index (In Decimal):

Pages:

0,1,2

Size: 16 bits

BITS DESCRIPTION TYPE DEFAULT

15 Software Next Page

0 = Last page

1 = More pages to follow

R/W 0b

14 RESERVED RO -

13 Software Message Page

0 = unformatted page

1 = message page

R/W 1b

12 Acknowledge

0 = device cannot comply with message

1 = device will comply with message

R/W 0b

11 Toggle

0 = previous transmitted LCW = 1

1 = previous transmitted LCW = 0

RO 0b

10:0 Message Code

Message/Unformatted Code Field

RW 000

0000

0001b

LAN7850

DS00001993D-page 232  2015 - 2017 Microchip Technology Inc.

15.3.1.9 Ethernet PHY Auto-Negotiation Link Partner Next Page RX Register

Index (In Decimal):

Pages:

0,1,2

Size: 16 bits

BITS DESCRIPTION TYPE DEFAULT

15 Link Partner Software Next Page

0 = Last page

1 = More pages to follow

RO 0b

14 Link Partner Acknowledge

0 = Link code word not yet received from partner

1 = Link code word received from partner

RO 0b

13 Link Partner Software Message Page

0 = unformatted page

1 = message page

RO 0b

12 Acknowledge from Link Partner

0 = device cannot comply with message

1 = device will comply with message

RO 0b

11 Link Partner Toggle

0 = previous transmitted LCW = 1

1 = previous transmitted LCW = 0

RO 0b

10:0 Link Partner Message Code

Message/Unformatted Code Field

RO 000

0000

0000b

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 233

LAN7850

15.3.1.10 Ethernet PHY 1000BASE-T Control Register

Index (In Decimal):

Pages:

0,1,2

Size: 16 bits

BITS DESCRIPTION TYPE DEFAULT

15:13 Test Mode

IEEE 802.3 clause 40.6.1.1.2 transmitter test mode.

000 = Normal mode

001 = Test Mode 1 - Transmit waveform test

010 = Test Mode 2 - Transmit jitter test in Master mode

011 = Test Mode 3 - Transmit jitter test in Slave mode

100 = Test Mode 4 - Transmitter distortion test

101 = Reserved

110 = Reserved

111 = Reserved

R/W 000b

12 Master/Slave Manual Configuration Enable

0 = disable MASTER-SLAVE manual configuration value

1 = enable MASTER-SLAVE manual configuration value

R/W 0b

11 Master/Slave Manual Configuration Value

Active only when the Master/Slave Manual Configuration Enable bit of this

0 = Configure PHY as slave

1 = Configure PHY as master

R/W 0b

10 Port Type

0 = single-port device

1 = multi-port device

R/W 0b

91000BASE-T Full Duplex

0 = advertise PHY is not 1000BASE-T full duplex capable

1 = advertise PHY is 1000BASE-T full duplex capable

R/W 1b

81000BASE-T Half Duplex

0 = advertise PHY is not 1000BASE-T half duplex capable

1 = advertise PHY is 1000BASE-T half duplex capable

R/W 1b

7:0 RESERVED RO -

LAN7850

DS00001993D-page 234  2015 - 2017 Microchip Technology Inc.

15.3.1.11 Ethernet PHY 1000BASE-T Status Register

Index (In Decimal):

Pages:

0,1,2

Size: 16 bits

BITS DESCRIPTION TYPE DEFAULT

15 Master/Slave Configuration Fault

0 = No MASTER-SLAVE configuration fault detected

1 = MASTER-SLAVE configuration fault detected

RO/LH 0b

14 Master/Slave Configuration Resolution

0 = Local PHY configuration resolved to SLAVE

1 = Local PHY configuration resolved to MASTER

RO 0b

13 Local 1000BASE-T Receiver Status

0 = Local Receiver not OK

1 = Local Receiver OK

RO 0b

12 Remote (Link Partner) Receiver Status

0 = Remote Receiver not OK

1 = Remote Receiver OK

RO 0b

11 Link Partner Advertised 1000BASE-T Full Duplex Capability

0 = Link Partner is not capable of 1000BASE-T full duplex

1 = Link Partner is capable of 1000BASE-T full duplex

RO 0b

10 Link Partner Advertised 1000BASE-T Half Duplex Capability

0 = Link Partner is not capable of 1000BASE-T half duplex

1 = Link Partner is capable of 1000BASE-T half duplex

RO 0b

9:8 RESERVED RO -

7:0 1000BASE-T Idle Error Count

Cumulative count of the errors detected when the receiver is receiving idles.

RO/SC 00h

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 235

LAN7850

15.3.1.12 Ethernet PHY MMD Access Control Register

15.3.1.13 Ethernet PHY MMD Access Address/Data Register

Index (In Decimal):

Pages:

0,1,2

Size: 16 bits

BITS DESCRIPTION TYPE DEFAULT

15:14 MMD Access Function

00 = Address

01 = Data, no post-increment

10 = Data, post-increment on reads and writes

11 = Data, post-increment on writes only

R/W 00b

13:5 RESERVED RO -

4:0 MMD Access Device Address R/W 00000b

Note: Auto-address incrementing in a write is not supported.

Note: Refer to Section 15.4, "MDIO Manageable Device (MMD) Control and Status Registers," on page 259 for

details on the available MMD registers.

Index (In Decimal):

Pages:

0,1,2

Size: 16 bits

BITS DESCRIPTION TYPE DEFAULT

15:0 MMD Address/Data

If MMD Access Device Address is 00b, this field is the MMD address.

Otherwise, this field is the MMD data.

R/W 0000h

Note: Refer to Section 15.4, "MDIO Manageable Device (MMD) Control and Status Registers," on page 259 for

details on the available MMD registers.

LAN7850

DS00001993D-page 236  2015 - 2017 Microchip Technology Inc.

15.3.1.14 Ethernet PHY 1000BASE-T Status Extension 1 Register

Index (In Decimal):

Pages:

0,1,2

Size: 16 bits

BITS DESCRIPTION TYPE DEFAULT

15 1000BASE-X Full Duplex

0 = PHY not able to perform full duplex 1000BASE-X

1 = PHY able to perform full duplex 1000BASE-X

RO 0b

14 1000BASE-X Half Duplex

0 = PHY not able to perform half duplex 1000BASE-X

1 = PHY able to perform half duplex 1000BASE-X

RO 0b

13 1000BASE-T Full Duplex

0 = PHY not able to perform full duplex 1000BASE-T

1 = PHY able to perform full duplex 1000BASE-T

RO 1b

12 1000BASE-T Half Duplex

0 = PHY not able to perform half duplex 1000BASE-T

1 = PHY able to perform half duplex 1000BASE-T

RO 1b

11:0 RESERVED RO -

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 237

LAN7850

15.3.1.15 Ethernet PHY 100BASE-TX Status Extension Register

Index (In Decimal):

Page:

Size: 16 bits

BITS DESCRIPTION TYPE DEFAULT

15 100BASE-TX Descrambler Locked RO 0b

14 100BASE-TX Descrambler Lock Error Detected RO/SC 0b

13 100BASE-TX Link-Disconnect State RO/SC 0b

12 100BASE-TX Current Link Status RO 0b

11 100BASE-TX Receive Error Detected RO/SC 0b

10 100BASE-TX Transmit Error Detected RO/SC 0b

9100BASE-TX Start-of-stream Delimiter Error Detected RO/SC 0b

8100BASE-TX End-of-stream Delimiter Error Detected RO/SC 0b

7:0 RESERVED RO -

LAN7850

DS00001993D-page 238  2015 - 2017 Microchip Technology Inc.

15.3.1.16 Ethernet PHY 1000BASE-T Status Extension 2 Register

Index (In Decimal):

Page:

Size: 16 bits

BITS DESCRIPTION TYPE DEFAULT

15 1000BASE-T Descrambler Locked RO 0b

14 1000BASE-T Descrambler Lock Error Detected RO/SC 0b

13 1000BASE-T Link-Disconnect State RO/SC 0b

12 1000BASE-T Current Link Status RO 0b

11 1000BASE-T Receive Error Detected RO/SC 0b

10 1000BASE-T Transmit Error Detected RO/SC 0b

91000BASE-T Start-of-stream Delimiter Error Detected RO/SC 0b

81000BASE-T End-of-stream Delimiter Error Detected RO/SC 0b

71000BASE-T Carrier Extension Error Detected RO/SC 0b

6Non-compliant 1000BASE-T BCM5400 Detected RO 0b

5MDI Crossover Error Detected RO 0b

4:0 RESERVED RO -

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 239

LAN7850

15.3.1.17 Ethernet PHY Bypass Control Register

Index (In Decimal):

Page:

Size: 16 bits

BITS DESCRIPTION TYPE DEFAULT

15 Disabled Transmitter Output to Media R/W 0b

14 Bypass 4B/5B Encoder/Decoder R/W 0b

13 Bypass Scrambler R/W 0b

12 Bypass Descrambler R/W 0b

11 Bypass PCS Receive R/W 0b

10 Bypass PCS Transmit R/W 0b

9Bypass Link Fail Inhibit Timer R/W 0b

8RESERVED RO -

7Disable Auto-MDI/MDI-X in Forced 10/100 Mode R/W 1b

6Non-compliant BCM5400 Detect Disable R/W 0b

5Disable Auto-MDI/MDI-X Correction R/W 0b

4Disable Polarity Inversion Correction R/W 0b

3Ignore Advertised Ability

0 = Ignore advertised ability in parallel detect enable

1 = Do not ignore advertised ability

R/W 1b

2Pulse Shape Filter Disable

Disables (0.75 + 0.25z-1) pulse shaping filter in 1000BASE-T transmitter

R/W 0b

1Automatic 1000BASE-T Next-page Exchange Disable

Disables automatic 1000BASE-T next-page exchanges

R/W 0b

0RESERVED RO -

LAN7850

DS00001993D-page 240  2015 - 2017 Microchip Technology Inc.

15.3.1.18 100BASE-TX/1000BASE-T Receive Error Counter Register

15.3.1.19 100BASE-TX/1000BASE-T False Carrier Error Counter Register

15.3.1.20 10BASE-T/100BASE-TX/1000BASE-T Link Disconnect Counter Register

Index (In Decimal):

Page:

Size: 16 bits

BITS DESCRIPTION TYPE DEFAULT

15:8 RESERVED RO -

7:0 100BASE-TX/1000BASE-T Receive Error Counter

This single counter counts both 100BASE-TX and 1000BASE-T events when

the respective link is up. The counter saturates at 255 and clears upon being

read.

RO/SC 00h

Index (In Decimal):

Page:

Size: 16 bits

BITS DESCRIPTION TYPE DEFAULT

15:8 RESERVED RO -

7:0 100BASE-TX/1000BASE-T False Carrier Error Counter

This single counter counts both 100BASE-TX and 1000BASE-T events when

the respective link is up. The counter saturates at 255 and clears upon being

read.

RO/SC 00h

Index (In Decimal):

Page:

Size: 16 bits

BITS DESCRIPTION TYPE DEFAULT

15:8 RESERVED RO -

7:0 10BASE-T/100BASE-TX/1000BASE-T Link Disconnect Counter

This counter counts all copper PHY link drops. The counter saturates at 255

and clears upon being read.

RO/SC 00h

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 241

LAN7850

15.3.1.21 Ethernet PHY Extended 10BASE-T Control and Status Register

Index (In Decimal):

Page:

Size: 16 bits

BITS DESCRIPTION TYPE DEFAULT

15 Disable 10BASE-T Link-integrity State Machine R/W 0b

14 Disable 10BASE-T Jabber Detect R/W 0b

13 Disable 10BASE-T Echo Mode R/W 1b

12 Disable 10BASE-T Signal Quality Error Test R/W 1b

11:10 10BASE-T Squelch Threshold Control

00 = Nominal squelch threshold (300 mV)

01 = Reduced squelch threshold (197 mV)

10 = Raised squelch threshold (450 mV)

11 = RESERVED

R/W 00b

9Sticky Reset Enable R/W 1b

8EOF Error Detected RO/SC 0b

710BASE-T Disconnected RO/SC 0b

610BASE-T Link Status RO 0b

5:3 RESERVED RO -

2:1 Carrier-Sense Control

00 = CRS equals receiving or (transmitting & ~FDX)

01 = CRS equals (receiving or transmitting) & ~FDX

10 = CRS equals receiving

11 = CRS equals receiving & ~FDX

Where FDX=1 in full-duplex mode.

R/W 00b

0 RESERVED RO -

LAN7850

DS00001993D-page 242  2015 - 2017 Microchip Technology Inc.

15.3.1.22 Ethernet PHY Extended PHY Control 1 Register

15.3.1.23 Ethernet PHY Extended PHY Control 2 Register

Index (In Decimal):

Page:

Size: 16 bits

BITS DESCRIPTION TYPE DEFAULT

15:4 RESERVED RO -

3Far-End Loopback Enable R/W 0b

2:0 RESERVED RO -

Index (In Decimal):

Page:

Size: 16 bits

BITS DESCRIPTION TYPE DEFAULT

15:13 100BASE-TX Edge Rate Control

011 = +3 edge rate (slowest)

010 = +2 edge rate

001 = +1 Default edge rate

000 = Default edge rate

111 = -1 edge rate

110 = -2 edge rate

101 = -3 edge rate

100 = -4 edge rate (fastest)

R/W 000b

12:6 RESERVED RO -

5:4 Jumbo Packet FIFO Configuration

00 = Normal IEEE 1518-byte packet length

01 = 9000-byte jumbo packet length

10 = 12000-byte jumbo packet length

11 = RESERVED

R/W 00b

3:1 RESERVED RO -

0Cable Loopback Mode Enable R/W 0b

 2015 - 2017 Microchip Technology Inc. DS00001993D-page 243

LAN7850

15.3.1.24 Ethernet PHY Interrupt Mask Register

Index (In Decimal):

Page:

Size: 16 bits

BITS DESCRIPTION TYPE DEFAULT

15 Interrupt Enable R/W 0b

14 Speed State-Change Interrupt Mask R/W 0b

13 Link State-Change Interrupt Mask R/W 0b

12 Full Duplex State-Change Interrupt Mask R/W 0b

11 Auto-Negotiation Error Interrupt Mask R/W 0b

10 Auto-Negotiation Complete Interrupt Mask R/W 0b

9In-line Powered Device (PoE) Detected Interrupt Mask R/W 0b

8Symbol Error Interrupt Mask R/W 0b

7Fast Link Failure Interrupt Mask R/W 0b

6RESERVED RO -

5Extended Interrupt Mask R/W 0b

4Wake on LAN (WoL) Interrupt Mask R/W 0b

3False-carrier Interrupt Mask R/W 0b

2Link Speed Downshift Detected Interrupt Mask R/W 0b

1Master/Slave Resolution Error Interrupt Mask R/W 0b

0RX_ER Interrupt Mask R/W 0b

Note: No status bit is set in the Ethernet PHY Interrupt Status Register if the corresponding interrupt mask bit in

the Ethernet PHY Interrupt Mask Register is clear. When an interrupt mask is clear, the actual correspond-

ing interrupt condition may still be set internally (i.e., it is “pending”), but will not be reflected in the corre-

sponding Ethernet PHY Interrupt Status Register bit. In the latter case, any pending internal interrupt

condition will be reflected in the corresponding Ethernet PHY Interrupt Status Register bit when the corre-

sponding bit is set in the Ethernet PHY Interrupt Mask Register. The actual interrupt condition will be

cleared when the Ethernet PHY Interrupt Status Register is read, but only if the corresponding interrupt

mask bit is set at the time of the Ethernet PHY Interrupt Status Register read. Therefore, the following

sequence for enabling interrupts is recommended:

1. Write the Ethernet PHY Interrupt Mask Register to enable the desired interrupts by setting the individual

bits, but DO NOT set the Interrupt Enable bit. This prevents any pending interrupts from being reflected on

the Interrupt Status bit of the Ethernet PHY Interrupt Status Register and therefore the interrupt pin will not

assert.

2. Read the Ethernet PHY Interrupt Status Register to clear any pending interrupts for enabled interrupt

sources. If necessary, service those actions as required.

3. Write the Ethernet PHY Interrupt Mask Register to enable the desired interrupts (set individual bits) AND

the Interrupt Enable bit concurrently. Now all desired NEW interrupts can be received with no risk of previ-

ously generated interrupts being reflected.

LAN7850

DS00001993D-page 244  2015 - 2017 Microchip Technology Inc.

15.3.1.25 Ethernet PHY Interrupt Status Register

Index (In Decimal):

Page:

Size: 16 bits

BITS DESCRIPTION TYPE DEFAULT

15 Interrupt Status R/W 0b

14 Speed State-Change Interrupt Status R/W 0b

13 Link State-Change Interrupt Status R/W 0b

12 Full Duplex State-Change Interrupt Status R/W 0b

11 Auto-Negotiation Error Interrupt Status R/W 0b

10 Auto-Negotiation Complete Interrupt Status R/W 0b

9In-line Powered Device (PoE) Detected Interrupt Status R/W 0b

8Symbol Error Interrupt Status R/W 0b

7Fast Link Failure Interrupt Status R/W 0b

6RESERVED RO -

5Extended Interrupt Status R/W 0b

4Wake on LAN (WoL) Interrupt Status R/W 0b

3False-carrier Interrupt Status R/W 0b

2Link Speed Downshift Interrupt Status R/W 0b

1Master/Slave Resolution Error Interrupt Status R/W 0b

0RX_ER Interrupt Status R/W 0b