AT91R40008-66AU-999 - MICROCHIP TECHNOLOGY

Features

•Incorporates the ARM7TDMI™ ARM® Thumb® Processor Core

– High-performance 32-bit RISC Architecture

– High-density 16-bit Instruction Set

– Leader in MIPS/Watt

– Embedded ICE (In-Circuit Emulation)

•On-chip SRAM and/or ROM

– 32-bit Data Bus

– Single-clock Cycle Access

•Fully Programmable External Bus Interface (EBI)

– Maximum External Address Space of 64M Bytes

– Up to 8 Chip Selects

– Software Programmable 8/16-bit External Databus

•8-level Priority, Individually Maskable, Vectored Interrupt Controller

– 4 External Interrupts, Including a High-priority Low-latency Interrupt Request

•32 Programmable I/O Lines

•3-channel 16-bit Timer/Counter

– 3 External Clock Inputs

– 2 Multi-purpose I/O Pins per Channel

•2 USARTs

– 2 Dedicated Peripheral Data Controller (PDC) Channels per USART

•Programmable Watchdog Timer

•Advanced Power-saving Features

– CPU and Peripheral Can be Deactivated Individually

•Available in a 100-lead TQFP Package

Description

The AT91X40 Series is a subset of the Atmel AT91 16/32-bit microcontroller family,

which is based on the ARM7TDMI processor core. This processor has a high-perfor-

mance 32-bit RISC architecture with a high-density 16-bit instruction set and very low

power consumption. In addition, a large number of internally banked registers result in

very fast exception handling, making the device ideal for real-time control applications.

The AT91X40 Series features a direct connection to off-chip memory, including Flash,

through the fully programmable External Bus Interface (EBI). An eight-level priority

vectored interrupt controller, in conjunction with the Peripheral Data Controller signifi-

cantly improve the real-time performance of the device.

The devices are manufactured using Atmel’s high-density CMOS technology. By com-

bining the ARM7TDMI processor core with on-chip high-speed memory and a wide

range of peripheral functions on a monolithic chip, the Atmel AT91X40 Series is a fam-

ily of powerful microcontrollers that offer a flexible, cost-effective solution to many

compute-intensive embedded control applications.

Microcontroller Primary SRAM Bank Secondary SRAM Bank ROM

AT91M40800 8K Bytes – –

AT91R40807 8K Bytes 128K Bytes –

AT91M40807 8K Bytes – 128K Bytes

AT91R40008 256K Bytes – –

AT91

ARM® Thumb®

Microcontrollers

AT91M40800

AT91R40807

AT91M40807

AT91R40008

Rev. 1354D–ATARM–08/02

2AT91X40 Series

1354D–ATARM–08/02

Pin Configuration

Figure 1. AT91X40 Series Pinout (Top View)

P21/TXD1/NTRI

P20/SCK1

P19

P18

P17

P16

P15/RXD0

P14/TXD0

P13/SCK0

P12/FIQ

GND

P11/IRQ2

P10/IRQ1

VDDIO

VDDCORE

P9/IRQ0

P8/TIOB2

P7/TIOA2

P6/TCLK2

P5/TIOB1

P4/TIOA1

P3/TCLK1

GND

P2/TIOB0

P1/TIOA0

P0/TCLK0

D15

D14

D13

D12

VDDIO

D11

D10

GND

P31/A23/CS4

P30/A22/CS5

VDDIO

VDDCORE

P29/A21/CS6

P22/RXD1

NWR1/NUB

GND

NRST

NWDOVF

VDDIO

MCKI

P23

P24/BMS

P25/MCKO

GND

TMS

TDO

TCK

NRD/NOE

NWR0/NWE

VDDCORE

VDDIO

NWAIT

NCS0

NCS1

P26/NCS2

P27/NCS3

A0/NLB

A2A2

VDDIO

A10

A11

A12

A13

A14

GND

A15

A16

A17

A18

A19

P28/A20/CS7

GND

100-lead TQFP

116

100

TDI

AT91X40 Series

1354D–ATARM–08/02

Table 1. AT91X40 Series Pin Description

Module Name Function Type

Active

Level Comments

EBI A0 - A23 Address Bus Output – All valid after reset

D0 - D15 Data Bus I/O –

NCS0 - NCS3 Chip Select Output Low

CS4 - CS7 Chip Select Output High A23 - A20 after reset

NWR0 Lower Byte 0 Write Signal Output Low Used in Byte Write option

NWR1 Upper Byte 1 Write Signal Output Low Used in Byte Write option

NRD Read Signal Output Low Used in Byte Write option

NWE Write Enable Output Low Used in Byte Select option

NOE Output Enable Output Low Used in Byte Select option

NUB Upper Byte Select Output Low Used in Byte Select option

NLB Lower Byte Select Output Low Used in Byte Select option

NWAIT Wait Input Input Low

BMS Boot Mode Select Input – Sampled during reset

AIC FIQ Fast Interrupt Request Input – PIO-controlled after reset

IRQ0 - IRQ2 External Interrupt Request Input – PIO-controlled after reset

TC TCLK0 - TCLK2 Timer External Clock Input – PIO-controlled after reset

TIOA0 - TIOA2 Multipurpose Timer I/O Pin A I/O – PIO-controlled after reset

TIOB0 - TIOB2 Multipurpose Timer I/O Pin B I/O – PIO-controlled after reset

USART SCK0 - SCK1 External Serial Clock I/O – PIO-controlled after reset

TXD0 - TXD1 Transmit Data Output Output – PIO-controlled after reset

RXD0 - RXD1 Receive Data Input Input – PIO-controlled after reset

PIO P0 - P31 Parallel IO Line I/O –

WD NWDOVF Watchdog Overflow Output Low Open-drain

Clock MCKI Master Clock Input Input – Schmidt trigger

MCKO Master Clock Output Output –

Reset NRST Hardware Reset Input Input Low Schmidt trigger

NTRI Tri-state Mode Select Input Low Sampled during reset

ICE TMS Test Mode Select Input – Schmidt trigger, internal pull-up

TDI Test Data Input Input – Schmidt trigger, internal pull-up

TDO Test Data Output Output –

TCK Test Clock Input – Schmidt trigger, internal pull-up

Power VDDIO I/O Power Power –

VDDCORE Core Power Power –

GND Ground Ground –

4AT91X40 Series

1354D–ATARM–08/02

Block Diagram Figure 2. AT91X40 Series

ARM7TDMI Core

Embedded

ICE

Reset

EBI: External Bus Interface

ASB

Controller

Clock

AIC: Advanced

Interrupt Controller

AMBA Bridge

EBI User

Interface

TC: Timer

Counter

TC0

TC1

TC2

USART0

USART1

2 PDC

Channels

2 PDC

Channels

PIO: Parallel I/O Controller

PS: Power Saving

Chip ID

WD: Watchdog

Timer

APB

ASB

NRST

D0-D15

A1-A19

A0/NLB

NRD/NOE

NWR0/NWE

NWR1/NUB

NWAIT

NCS0

NCS1

P26/NCS2

P27/NCS3

P28/A20/CS7

P29/A21/CS6

P30/A22/CS5

P31/A23/CS4

P0/TCLK0

P3/TCLK1

P6/TCLK2

P1/TIOA0

P2/TIOB0

P4/TIOA1

P5/TIOB1

P7/TIOA2

P8/TIOB2

NWDOVF

TMS

TDO

TDI

TCK

MCKI

P25/MCKO

P12/FIQ

P9/IRQ0

P10/IRQ1

P11/IRQ2

P13/SCK0

P14/TXD0

P15/RXD0

P20/SCK1

P21/TXD1/NTRI

P22/RXD1

P16

P17

P18

P19

P23

P24/BMS

RAM

ROM

Extended SRAM

AT91X40 Series

1354D–ATARM–08/02

Architectural

Overview

The AT91X40 Series Microcontrollers integrate an ARM7TDMI with its embedded ICE

interface, memories and peripherals. The series’ architecture consists of two main

buses, the Advanced System Bus (ASB) and the Advanced Peripheral Bus (APB).

Designed for maximum performance and controlled by the memory controller, the ASB

interfaces the ARM7TDMI processor with the on-chip 32-bit memories, the External Bus

Interface (EBI) and the AMBA™ Bridge. The AMBA Bridge drives the APB, which is

designed for accesses to on-chip peripherals and optimized for low-power consumption.

The AT91X40 Series Microcontrollers implement the ICE port of the ARM7TDMI proces-

sor on dedicated pins, offering a complete, low-cost and easy-to-use debug solution for

target debugging.

Memories The AT91X40 Series Microcontrollers embed up to 256K bytes of internal SRAM, and

up to 128K bytes of ROM. The internal memories are directly connected to the 32-bit

data bus and are single-cycle accessible. This provides maximum performance of 0.9

MIPS/MHz by using the ARM instruction set of the processor, minimizing system power

consumption and improving the performance of separate memory solutions.

The AT91X40 Series Microcontrollers feature an External Bus Interface (EBI), which

enables connection of external memories and application-specific peripherals. The EBI

supports 8- or 16-bit devices and can use two 8-bit devices to emulate a single 16-bit

device. The EBI implements the early read protocol, enabling faster memory accesses

than standard memory interfaces.

Peripherals The AT91X40 Series Microcontrollers integrate several peripherals, which are classified

as system or user peripherals. All on-chip peripherals are 32-bit accessible by the

AMBA Bridge, and can be programmed with a minimum number of instructions. The

peripheral register set is composed of control, mode, data, status and enable/dis-

able/status registers.

An on-chip Peripheral Data Controller (PDC) transfers data between the on-chip

USARTs and on- and off-chip memories address space without processor intervention.

Most importantly, the PDC removes the processor interrupt handling overhead, making

it possible to transfer up to 64K continuous bytes without reprogramming the start

address, thus increasing the performance of the microcontroller, and reducing the power

consumption.

System Peripherals The External Bus Interface (EBI) controls the external memory or devices via an 8-bit or

16-bit data bus, and is programmed through the Advanced Peripheral Bus (APB). Each

chip select line has its own programming register.

The Power Saving (PS) module implements the Idle Mode (ARM7TDMI core clock

stopped until the next interrupt) and enables the user to adapt the power consumption of

the microcontroller to application requirements (independent peripheral clock control).

The Advanced Interrupt Controller (AIC) controls the internal sources from the internal

peripherals and the four external interrupt lines (including the FIQ) to provide an inter-

rupt and/or fast interrupt request to the ARM7TDMI. It integrates an 8-level priority

controller, and, using the Auto-vectoring feature, reduces the interrupt latency time.

The Parallel Input/Output Controller (PIO) controls up to 32 I/O lines. It enables the user

to select specific pins for on-chip peripheral input/output functions, and general-purpose

input/output signal pins. The PIO controller can be programmed to detect an interrupt on

a signal change from each line.

6AT91X40 Series

1354D–ATARM–08/02

The Watchdog (WD) can be used to prevent system lock-up if the software becomes

trapped in a deadlock.

The Special Function (SF) module integrates the Chip ID, the Reset Status and the Pro-

tect registers.

User Peripherals Two USARTs, independently configurable, enable communication at a high baud rate in

Synchronous or Asynchronous Mode. The format includes start, stop and parity bits and

up to 8 data bits. Each USART also features a Timeout and a Time Guard register, facil-

itating the use of the two dedicated Peripheral Data Controller (PDC) channels.

The 3-channel, 16-bit Timer Counter (TC) is highly-programmable and supports Capture

or Waveform Modes. Each TC channel can be programmed to measure or generate dif-

ferent kinds of waves, and can detect and control two input/output signals. The TC also

has 3 external clock signals.

AT91X40 Series

1354D–ATARM–08/02

Associated

Documentation

Table 2. Associated Documentation

Product Information Document Title

AT91M40800

Internal architecture of processor

ARM/Thumb instruction sets

Embedded in-circuit-emulator

ARM7TDMI (Thumb) Datasheet

Pinout

Mechanical characteristics

Ordering information

AT91M40800 Summary Datasheet

Timings

DC characteristics

AT91M40800 Electrical Characteristics

AT91R40807

Internal architecture of processor

ARM/Thumb instruction sets

Embedded in-circuit-emulator

ARM7TDMI (Thumb) Datasheet

Pinout

Mechanical characteristics

Ordering information

AT91R40807 Summary Datasheet

Timings

DC characteristics

AT91R40807 Electrical Characteristics

AT91M40807

Internal architecture of processor

ARM/Thumb instruction sets

Embedded in-circuit-emulator

ARM7TDMI (Thumb) Datasheet

Pinout

Mechanical characteristics

Ordering information

AT91M40807 Summary Datasheet

Timings

DC characteristics

AT91M40807 Electrical Characteristics

AT91R40008

Internal architecture of processor

ARM/Thumb instruction sets

Embedded in-circuit-emulator

ARM7TDMI (Thumb) Datasheet

Pinout

Mechanical characteristics

Ordering information

AT91R40008 Summary Datasheet

Timings

DC characteristics

AT91R40008 Electrical Characteristics

8AT91X40 Series

1354D–ATARM–08/02

Product Overview

Power Supply The AT91x40 Series Microcontrollers have two types of power supply pins - VDDIO and

VDDCORE. However, the AT91M40800, the AT91M40807 and the AT91R40807 have

single-supply VDD, VDDIO and VDDCORE pins that have to be tied to the same volt-

age. For further details on power supplies and acceptable voltage range on VDD,

VDDIO and VDDCORE, refer to the product Summary Datasheet or the product Electri-

cal Characteristics datasheet.

Input/Output

Considerations

The AT91M40807, the AT91R40807 and the AT91R40008 accept voltage levels up to

their power supply limit on the pads.

The AT91M40800 Microcontroller I/O pads are 5V-tolerant, enabling it to interface with

external 5V devices without any additional components. 5V-tolerant means that the

AT91M40800 accepts 5V (3V) on the inputs even if it is powered at 3V (2V). Refer to the

AT91M40800 Electrical Characteristics datasheet for further details.

After the reset, the peripheral I/Os are initialized as inputs to provide the user with maxi-

mum flexibility. It is recommended that in any application phase, the inputs to the

AT91X40 Series Microcontroller be held at valid logic levels to minimize the power

consumption.

Master Clock The AT91X40 Series Microcontrollers have a fully static design and work on the Master

Clock (MCK), provided on the MCKI pin from an external source.

The Master Clock is also provided as an output of the device on the pin MCKO, which is

multiplexed with a general-purpose I/O line. While NRST is active, the MCKO stays low.

After the reset, the MCKO is valid and outputs an image of the MCK signal. The PIO

Controller must be programmed to use this pin as standard I/O line.

Reset Reset restores the default states of the user interface registers (defined in the user inter-

face of each peripheral), and forces the ARM7TDMI to perform the next instruction fetch

from address zero. Except for the program counter the ARM7TDMI registers do not

have defined reset states.

NRST Pin NRST is active low-level input. It is asserted asynchronously, but exit from reset is syn-

chronized internally to the MCK. The signal presented on MCK must be active within the

specification for a minimum of 10 clock cycles up to the rising edge of NRST, to ensure

correct operation. The first processor fetch occurs 80 clock cycles after the rising edge

of NRST.

Watchdog Reset The watchdog can be programmed to generate an internal reset. In this case, the reset

has the same effect as the NRST pin assertion, but the pins BMS and NTRI are not

sampled. Boot Mode and Tri-state Mode are not updated. If the NRST pin is asserted

and the watchdog triggers the internal reset, the NRST pin has priority.

Emulation Function

Tri-state Mode The AT91X40 Series provides a tri-state mode, which is used for debug purposes. This

enables the connection of an emulator probe to an application board without having to

desolder the device from the target board. In tri-state mode, all the output pin drivers of

the AT91X40 Series Microcontroller are disabled.

AT91X40 Series

1354D–ATARM–08/02

To enter tri-state mode, the pin NTRI must be held low during the last 10 clock cycles

before the rising edge of NRST. For normal operation, the pin NTRI must be held high

during reset, by a resistor of up to 400K Ohm.

NTRI is multiplexed with I/O line P21 and USART 1 serial data transmit line TXD1.

Standard RS-232 drivers generally contain internal 400K Ohm pull-up resistors. If TXD1

is connected to a device not including this pull-up, the user must make sure that a high

level is tied on NTRI while NRST is asserted.

JTAG/ICE Debug ARM standard embedded In-circuit Emulation is supported via the JTAG/ICE port. The

pins TDI, TDO, TCK and TMS are dedicated to this debug function and can be con-

nected to a host computer via the external ICE interface.

In ICE Debug Mode, the ARM7TDMI core responds with a non-JTAG chip ID that identi-

fies the microcontroller. This is not fully IEEE1149.1 compliant.

Memory Controller The ARM7TDMI processor address space is 4G bytes. The memory controller decodes

the internal 32-bit address bus and defines three address spaces:

• Internal Memories in the four lowest megabytes

• Middle Space reserved for the external devices (memory or peripherals) controlled

by the EBI

• Internal Peripherals in the four highest megabytes

In any of these address spaces, the ARM7TDMI operates in Little-Endian Mode only.

Internal Memories The AT91X40 Series Microcontrollers integrate one or two banks of internal static

SRAM and/or one bank of ROM. All internal memories are 32 bits wide and single-clock

cycle accessible. Byte (8-bit), halfword (16-bit) or word (32-bit) accesses are supported

and are executed within one cycle. Fetching Thumb or ARM instructions is supported

and internal memory can store twice as many Thumb instructions as ARM ones.

All the AT91X40 Series Microcontrollers integrate a primary 8-Kbyte or 256-Kbyte

SRAM bank, accessible at address 0x0 (after the remap).

The AT91R40807 integrates a secondary SRAM memory bank of 128K bytes at

address 0x10 0000. This secondary bank can be used to emulate the ROM of the

AT91M40807.

The AT91M40807 Microcontroller integrates 128K bytes of internal ROM at address

0x10 0000. It offers a reduced-cost option of the AT91R40807 for high-volume applica-

tions in which the software is stable.

Using Internal Memories The primary RAM bank is always mapped at address 0x30 0000 before remap and at

address 0x0 after the remap, allowing ARM7TDMI exception vectors to be modified by

the software. Making the RAM bank accessible before remap allows the user to copy

ARM exception vectors and boot code into the bank prior to remap.

The rest of the bank can be used for stack allocation to speed up context saving and

restoration, or as data and program storage for critical algorithms.

Placing the SRAM on-chip and using a 32-bit data bus bandwidth maximizes microcon-

troller performance while minimizing system power consumption. The 32-bit bus

optimizes use of the ARM instruction set and offers the ability to process data wider than

16 bits, thus making optimal use of the ARM7TDMI advanced performance.

The capability to update application software dynamically in an internal SRAM bank

adds an extra dimension to the AT91X40 Series Microcontrollers.

10 AT91X40 Series

1354D–ATARM–08/02

ROM Emulation The AT91R40807 provides an ideal means of emulating the ROM version

AT91M40807. The secondary SRAM bank of the AT91R40807 is mapped to the same

address as the ROM of the AT91M40807. It is write-protected after a reset; writing 0x1

in the Memory Mode Register of the Special Function Module can disable this

protection.

At system power-up, the code is downloaded from an external non-volatile memory or

through a debugger to the on-chip secondary SRAM bank of the AT91R40807. After the

secondary SRAM bank write-protection is enabled, the application is in the same envi-

ronment as though it were running on an AT91M40807.

Boot Mode Select The ARM reset vector is at address 0x0. After the NRST line is released, the

ARM7TDMI executes the instruction stored at this address. This means that this

address must be mapped in non-volatile memory after the reset.

The input level on the BMS pin during the last 10 clock cycles before the rising edge of

the NRST selects the type of boot memory. The Boot Mode depends on BMS and

whether or not the AT91X40 Series Microcontroller has on-chip ROM or extended

SRAM (see Table 3).

The AT91R40807 supports boot in on-chip extended SRAM, for the purpose of emulat-

ing ROM versions. In this case, the microcontroller must first boot from external non-

volatile memory, and ensure that a valid program is downloaded in the on-chip extended

SRAM. Then, the NRST must be reasserted by external circuitry after the level on the

pin BMS is changed.

The pin BMS is multiplexed with the I/O line P24 that can be programmed after reset like

any standard PIO line.

Remap Command The ARM vectors (Reset, Abort, Data Abort, Prefetch Abort, Undefined Instruction,

Interrupt, Fast Interrupt) are mapped from address 0x0 to address 0x20. In order to

allow these vectors to be redefined dynamically by the software, the AT91X40 Series

Microcontrollers use a remap command that enables switching between the boot mem-

ory and the internal primary SRAM bank addresses. The remap command is accessible

through the EBI User Interface, by writing one in RCB of EBI_RCR (Remap Control

devices (connected to chip selects 1 to 7) is required. The remap operation can only be

changed back by an internal reset or an NRST assertion.

Abort Control The abort signal providing a Data Abort or a Prefetch Abort exception to the ARM7TDMI

is asserted in the following cases:

• When accessing an undefined address in the EBI address space

• When writing to a write-protected internal memory area on the AT91R40807

Table 3. Boot Mode Select

BMS Product Boot Memory

AT91M40800 External 8-bit memory on NCS0

AT91R40807 Internal 32-bit extended SRAM

AT91M40807 Internal 32-bit ROM

AT91R40008 External 8-bit memory on NCS0

0 All External 16-bit memory on NCS0

AT91X40 Series

1354D–ATARM–08/02

No abort is generated when reading the internal memory or by accessing the internal

peripheral, whether the address is defined or not.

When a write-protected area is accessed, the memory controller detects it and gener-

ates an abort but does not cancel the access.

External Bus Interface The External Bus Interface handles the accesses between addresses 0x0040 0000 and

0xFFC0 0000. It generates the signals that control access to the external devices, and

can be configured from eight 1M byte banks up to four 16M bytes banks. It supports

byte, half-word and word aligned accesses.

For each of these banks, the user can program:

• Number of wait states

• Number of data float times (wait time after the access is finished to prevent any bus

contention in case the device is too long in releasing the bus)

• Data bus width (8-bit or 16-bit)

• With a 16-bit wide data bus, the user can program the EBI to control one 16-bit

device (Byte Access Select Mode) or two 8-bit devices in parallel that emulate a 16-

bit memory (Byte Write Access Mode).

The External Bus Interface features also the Early Read Protocol, configurable for all the

devices, that significantly reduces access time requirements on an external device in

the case of single clock cycle access.

Peripherals The AT91X40 Series’ peripherals are connected to the 32-bit wide Advanced Peripheral

Bus. Peripheral registers are only word accessible – byte and half-word accesses are

not supported. If a byte or a half-word access is attempted, the memory controller auto-

matically masks the lowest address bits and generates a word access.

Each peripheral has a 16-Kbyte address space allocated (the AIC only has a 4-Kbyte

address space).

Peripheral Registers The following registers are common to all peripherals:

• Control Register – write only register that triggers a command when a one is written

to the corresponding position at the appropriate address. Writing a zero has no

effect.

• Mode Register – read/write register that defines the configuration of the peripheral.

Usually has a value of 0x0 after a reset.

• Data Registers – read and/or write register that enables the exchange of data

between the processor and the peripheral.

• Status Register – read only register that returns the status of the peripheral.

• Enable/Disable/Status Registers are shadow command registers. Writing a one in

the Enable Register sets the corresponding bit in the Status Register. Writing a one

in the Disable Register resets the corresponding bit and the result can be read in the

Status Register. Writing a bit to zero has no effect. This register access method

maximizes the efficiency of bit manipulation, and enables modification of a register

with a single non-interruptible instruction, replacing the costly read-modify-write

operation.

Unused bits in the peripheral registers are shown as “–“ and must be written at 0 for

upward compatibility. These bits read 0.

12 AT91X40 Series

1354D–ATARM–08/02

Peripheral Interrupt Control The Interrupt Control of each peripheral is controlled from the status register using the

interrupt mask. The status register bits are ANDed to their corresponding interrupt mask

bits and the result is then ORed to generate the Interrupt Source signal to the Advanced

Interrupt Controller.

The interrupt mask is read in the Interrupt Mask Register and is modified with the Inter-

rupt Enable Register and the Interrupt Disable Register. The enable/disable/status (or

mask) makes it possible to enable or disable peripheral interrupt sources with a non-

interruptible single instruction. This eliminates the need for interrupt masking at the AIC

or Core level in real-time and multi-tasking systems.

Peripheral Data Controller The AT91X40 Series Microcontroller has a 4-channel PDC dedicated to the two on-chip

USARTs. One PDC channel is dedicated to the receiver and one to the transmitter of

each USART.

The user interface of a PDC channel is integrated in the memory space of each USART.

It contains a 32-bit Address Pointer Register (RPR or TPR) and a 16-bit Transfer

Counter Register (RCR or TCR). When the programmed number of transfers are per-

formed, a status bit indicating the end of transfer is set in the USART Status Register

and an interrupt can be generated.

System Peripherals

PS: Power-saving The Power-saving feature optimizes power consumption, enabling the software to stop

the ARM7TDMI clock (Idle Mode) and restarting it when the module receives an inter-

rupt (or reset). It also enables on-chip peripheral clocks to be enabled and disabled

individually, matching power consumption and application needs.

AIC: Advanced Interrupt

Controller

The AIC has an 8-level priority, individually maskable, vectored interrupt controller, and

drives the NIRQ and NFIQ pins of the ARM7TDMI from:

• The external fast interrupt line (FIQ)

• The three external interrupt request lines (IRQ0 - IRQ2)

• The interrupt signals from the on-chip peripherals

The AIC is extensively programmable, offering maximum flexibility, and its vectoring fea-

tures reduce the real-time overhead in handling interrupts.

The AIC also features a spurious vector, which reduces spurious interrupt handling to a

minimum, and a protect mode that facilitates the debug capabilities.

PIO: Parallel IO Controller The AT91X40 Series has 32 programmable I/O lines. Six pins are dedicated as general-

purpose I/O pins. Other I/O lines are multiplexed with an external signal of a peripheral

to optimize the use of available package pins. The PIO controller enables generation of

an interrupt on input change and insertion of a simple input glitch filter on any of the PIO

pins.

WD: Watchdog The Watchdog is built around a 16-bit counter, and is used to prevent system lock-up if

the software becomes trapped in a deadlock. It can generate an internal reset or inter-

rupt, or assert an active level on the dedicated pin NWDOVF. All programming registers

are password-protected to prevent unintentional programming.

AT91X40 Series

1354D–ATARM–08/02

SF: Special Function The AT91X40 Series provides registers that implement the following special functions.

• Chip identification

• RESET status

•Protect Mode

• Write protection for the AT91R40807 internal 128-Kbyte memory

14 AT91X40 Series

1354D–ATARM–08/02

User Peripherals

USART: Universal

Synchronous/

Asynchronous Receiver

Transmitter

The AT91X40 Series provides two identical, full-duplex, universal synchronous/asyn-

chronous receiver/transmitters.

Each USART has its own baud rate generator, and two dedicated Peripheral Data Con-

troller channels. The data format includes a start bit, up to 8 data bits, an optional

programmable parity bit and up to 2 stop bits.

The USART also features a Receiver Timeout register, facilitating variable length Frame

support when it is working with the PDC, and a Time Guard register, used when interfac-

ing with slow remote equipment.

TC: Timer Counter The AT91X40 Series features a Timer Counter block that includes three identical 16-bit

timer counter channels. Each channel can be independently programmed to perform a

wide range of functions, including frequency measurement, event counting, interval

measurement, pulse generation, delay timing and pulse-width modulation.

The Timer Counter can be used in Capture or Waveform Mode, and all three counter

channels can be started simultaneously and chained together.

AT91X40 Series

1354D–ATARM–08/02

Memory Map

Figure 3. AT91M40800/R40008 Memory Map Before and After the Remap Command

AfterBefore

Address Function Size Abort Control

0xFFFFFFFF

0xFFC00000

0xFFBFFFFF

0x00400000

0x003FFFFF

0x00300000

0x002FFFFF

0x00200000

0x001FFFFF

0x00100000

0x000FFFFF

0x00000000

On-chip

Peripherals

Reserved

On-chip

Primary

RAM Bank

Reserved

On-chip

Device

Reserved

On-chip

Device

External

Devices Selected

by NCS0

4M Bytes

1M Byte

Ye s

Address Function Size Abort Control

0xFFFFFFFF

0xFFC00000

0xFFBFFFFF

0x00400000

0x003FFFFF

0x00300000

0x002FFFFF

0x00200000

0x001FFFFF

0x00100000

0x000FFFFF

0x00000000

On-chip

Peripherals

External

Devices

(Up to 8)

Reserved

On-chip

Device

Reserved

On-chip

Device

On-chip

Primary

RAM Bank

4M Bytes

Up to 8 Devices

Programmable

Page Size

1, 4, 16, 64M Bytes

1M Byte

Ye s

1M Byte No

16 AT91X40 Series

1354D–ATARM–08/02

Figure 4. AT91R40807/M40807 Before and After the Remap Command

Address Function Size Abort Control

0xFFFFFFFF

0xFFC00000

0xFFBFFFFF

0x00400000

0x003FFFFF

0x00300000

0x002FFFFF

0x00200000

0x001FFFFF

0x00100000

0x000FFFFF

0x00000000

On-chip

Peripherals

External

Devices

(Up to 8)

Reserved

On-chip

Device

On-chip

ROM

Secondary

RAM Bank

On-chip

Primary

RAM Bank

4M Bytes

Up to 8 Devices

Programmable

Page Size

1, 4, 16, 64M Bytes

1M Byte

Ye s

(AT91R40807,

If Write-protect

Feature

is Enabled)

1M Byte No

Address Function Size Abort Control

0xFFFFFFFF

0xFFC00000

0xFFBFFFFF

0x00400000

0x003FFFFF

0x00300000

0x002FFFFF

0x00200000

0x001FFFFF

0x00100000

0x000FFFFF

0x00000000

On-chip

Peripherals

Reserved

On-chip

Primary

RAM Bank

Reserved

On-chip

Device

On-chip

ROM

Secondary

RAM Bank

External Device

Selected by NCS0

On-chip ROM

Secondary

RAM Bank

4M Bytes

1M Byte

Ye s

(AT91R40807,

If Write-protect

Feature is Enabled)

Ye s

AfterBefore

AT91X40 Series

1354D–ATARM–08/02

Peripheral Memory Map

Figure 5. Peripheral Memory Map

Address Peripheral Peripheral Name Size

0xFFFFFFFF

0xFFFFF000

0xFFFFBFFF

0xFFFF8000

0xFFFF7FFF

0xFFFF4000

0xFFFF3FFF

0xFFFF0000

0xFFFE3FFF

0xFFFE0000

0xFFFCFFFF

0xFFFCC000

0xFFFD3FFF

0xFFFD0000

0xFFF03FFF

0xFFF00000

0xFFE03FFF

0xFFE00000

0xFFC00000

AIC

PIO

USART1

USART0

EBI

Advanced Interrupt Controller

Reserved

WatchdogTimer

Power Saving

Parallel I/O Controller

Reserved

Timer Counter

Universal Synchronous/

Asynchronous

Receiver/Transmitter 1

Universal Synchronous/

Asynchronous

Receiver/Transmitter 0

Reserved

Special Function

External Bus Interface

Reserved

4K Bytes

16K Bytes

Reserved

18 AT91X40 Series

1354D–ATARM–08/02

EBI: External Bus

Interface

The EBI generates the signals that control the access to the external memory or periph-

eral devices. The EBI is fully-programmable and can address up to 64M bytes. It has

eight chip selects and a 24-bit address bus, the upper four bits of which are multiplexed

with a chip select.

The 16-bit data bus can be configured to interface with 8- or 16-bit external devices.

Separate read and write control signals allow for direct memory and peripheral

interfacing.

The EBI supports different access protocols allowing single-clock cycle memory

accesses.

The main features are:

• External memory mapping

• Up to 8 chip select lines

• 8- or 16-bit data bus

• Byte write or byte select lines

• Remap of boot memory

• Two different read protocols

• Programmable wait state generation

• External wait request

• Programmable data float time

The “EBI User Interface” is described on page 45.

External Memory

Mapping

The memory map associates the internal 32-bit address space with the external 24-bit

address bus.

The memory map is defined by programming the base address and page size of the

external memories (see “EBI User Interface” registers EBI_CSR0 to EBI_CSR7). Note

that A0 - A23 is only significant for 8-bit memory; A1 - A23 is used for 16-bit memory.

If the physical memory device is smaller than the programmed page size, it wraps

around and appears to be repeated within the page. The EBI correctly handles any valid

access to the memory device within the page (see Figure 6).

In the event of an access request to an address outside any programmed page, an

Abort signal is generated. Two types of Abort are possible: instruction prefetch abort

and data abort. The corresponding exception vector addresses are respectively

0x0000000C and 0x00000010. It is up to the system programmer to program the error

handling routine to use in case of an Abort (see the ARM7TDMI datasheet for further

information).

If two chip selects are defined as having the same base address, an access to the over-

lapping address space asserts both NCS lines. The Chip Select Register with the

smaller number defines the characteristics of the external access and the behavior of

the control signals.

AT91X40 Series

1354D–ATARM–08/02

Figure 6. External Memory Smaller than Page Size

1M Byte Device

Memory

Map

Low

Base

Base + 1M Bytes

Base + 2M Bytes

Base + 3M Bytes

Base + 4M Bytes

Repeat 1

Repeat 2

Repeat 3

20 AT91X40 Series

1354D–ATARM–08/02

External Bus Interface Pin Description

The following table shows how certain EBI signals are multiplexed:

Name Description Type

A0 - A23 Address bus (output) Output

D0 - D15 Data bus (input/output) I/O

NCS0 - NCS3 Active low chip selects (output) Output

CS4 - CS7 Active high chip selects (output) Output

NRD Read enable (output) Output

NWR0 - NWR1 Lower and upper write enable (output) Output

NOE Output enable (output) Output

NWE Write enable (output) Output

NUB, NLB Upper and lower byte select (output) Output

NWAIT Wait request (input) Input

Table 4. EBI Signals

Multiplexed Signals Functions

A23 - A20 CS4 - CS7 Allows from 4 to 8 chip select lines to be used

A0 NLB 8- or 16-bit data bus

NRD NOE Byte write or byte select access

NWR0 NWE Byte write or byte select access

NWR1 NUB Byte write or byte select access

AT91X40 Series

1354D–ATARM–08/02

Chip Select Lines The EBI provides up to eight chip select lines:

• Chip select lines NCS0 - NCS3 are dedicated to the EBI (not multiplexed).

• Chip select lines CS4 - CS7 are multiplexed with the top four address lines A23 -

A20.

By exchanging address lines for chip select lines, the user can optimize the EBI to suit

the external memory requirements: more external devices or larger address range for

each device.

The selection is controlled by the ALE field in EBI_MCR (Memory Control Register). The

following combinations are possible:

A20, A21, A22, A23 (configuration by default)

A20, A21, A22, CS4

A20, A21, CS5, CS4

A20, CS6, CS5, CS4

CS7, CS6, CS5, CS4

Figure 7. Memory Connections for Four External Devices

Note: For four external devices, the maximum address space per device is 16M bytes.

EBI

NCS0 - NCS3

NRD

NWRx

A0 - A23

D0 - D15

NCS3

NCS2

NCS1

NCS0

8 or 16

Memory Enable

Output Enable

Write Enable

A0 - A23

D0 - D15 or D0 - D7

22 AT91X40 Series

1354D–ATARM–08/02

Figure 8. Memory Connections for Eight External Devices

Note: For eight external devices, the maximum address space per device is 1M byte.

EBI

NCS0 - NCS3

NRD

NWRx

A0 - A19

D0 - D15

CS7

CS6

CS5

CS4

8 or 16

Memory Enable

NCS3

NCS2

NCS1

NCS0

Memory Enable

Output Enable

Write Enable

A0 - A19

D0 - D15 or D0 - D7

CS4 - CS7

AT91X40 Series

1354D–ATARM–08/02

Data Bus Width A data bus width of 8 or 16 bits can be selected for each chip select. This option is con-

trolled by the DBW field in the EBI_CSR (Chip Select Register) for the corresponding

chip select.

Figure 9 shows how to connect a 512K x 8-bit memory on NCS2.

Figure 9. Memory Connection for an 8-bit Data Bus

Figure 10 shows how to connect a 512K x 16-bit memory on NCS2.

Figure 10. Memory Connection for a 16-bit Data Bus

EBI

D0 - D7

D8 - D15

A1 - A18

NWR0

NRD

NCS2

D0 - D7

A1 - A18

Write Enable

Output Enable

Memory Enable

NWR1

EBI

D0 - D7

D8 - D15

A1 - A19

NLB

NWE

NOE

NCS2

D0 - D7

D8 - D15

A0 - A18

Low Byte Enable

Write Enable

Output Enable

Memory Enable

NUB High Byte Enable

24 AT91X40 Series

1354D–ATARM–08/02

Byte Write or Byte Select

Access

Each chip select with a 16-bit data bus can operate with one of two different types of

write access:

• Byte Write Access supports two byte write and a single read signal.

• Byte Select Access selects upper and/or lower byte with two byte select lines, and

separate read and write signals.

This option is controlled by the BAT field in the EBI_CSR (Chip Select Register) for the

corresponding chip select.

Byte Write Access is used to connect 2 x 8-bit devices as a 16-bit memory page.

• The signal A0/NLB is not used.

• The signal NWR1/NUB is used as NWR1 and enables upper byte writes.

• The signal NWR0/NWE is used as NWR0 and enables lower byte writes.

• The signal NRD/NOE is used as NRD and enables half-word and byte reads.

Figure 11 shows how to connect two 512K x 8-bit devices in parallel on NCS2.

Figure 11. Memory Connection for 2 x 8-bit Data Busses

EBI

D0 - D7

D8 - D15

A1 - A19

NWR0

NRD

NCS2

D0 - D7

A0 - A18

Write Enable

Read Enable

Memory Enable

NWR1

D8 - D15

A0 - A18

Write Enable

Read Enable

Memory Enable

AT91X40 Series

1354D–ATARM–08/02

Byte Select Access is used to connect 16-bit devices in a memory page.

• The signal A0/NLB is used as NLB and enables the lower byte for both read and

write operations.

• The signal NWR1/NUB is used as NUB and enables the upper byte for both read

and write operations.

• The signal NWR0/NWE is used as NWE and enables writing for byte or half word.

• The signal NRD/NOE is used as NOE and enables reading for byte or half word.

Figure 12 shows how to connect a 16-bit device with byte and half-word access (e.g. 16-

bit SRAM) on NCS2.

Figure 12. Connection for a 16-bit Data Bus with Byte and Half-word Access

Figure 13 shows how to connect a 16-bit device without byte access (e.g. Flash) on

NCS2.

Figure 13. Connection for a 16-bit Data Bus without Byte Write Capability.

EBI

D0 - D7

D8 - D15

A1 - A19

NLB

NWE

NOE

NCS2

D0 - D7

D8 - D15

A0 - A18

Low Byte Enable

Write Enable

Output Enable

Memory Enable

NUB High Byte Enable

EBI

D0 - D7

D8 - D15

A1 - A19

NLB

NWE

NOE

NCS2

D0 - D7

D8 - D15

A0 - A18

Write Enable

Output Enable

Memory Enable

NUB

26 AT91X40 Series

1354D–ATARM–08/02

Boot on NCS0 Depending on the device and the BMS pin level during the reset, the user can select

either an 8-bit or 16-bit external memory device connected on NCS0 as the Boot Mem-

ory. In this case, EBI_CSR0 (Chip Select Register 0) is reset at the following

configuration for chip select 0:

• 8 wait states (WSE = 1, NWS = 7)

• 8-bit or 16-bit data bus width, depending on BMS

Byte access type and number of data float time are respectively set to Byte Write

Access and 0. With a non-volatile memory interface, any values can be programmed for

these parameters.

Before the remap command, the user can modify the chip select 0 configuration, pro-

gramming the EBI_CSR0 with exact boot memory characteristics. the base address

becomes effective after the remap command, but the new number of wait states can be

changed immediately. This is useful if a boot sequence needs to be faster.

AT91X40 Series

1354D–ATARM–08/02

Read Protocols The EBI provides two alternative protocols for external memory read access: standard

and early read. The difference between the two protocols lies in the timing of the NRD

(read cycle) waveform.

The protocol is selected by the DRP field in EBI_MCR (Memory Control Register) and is

valid for all memory devices. Standard read protocol is the default protocol after reset.

Note: In the following waveforms and descriptions, NRD represents NRD and NOE since the

two signals have the same waveform. Likewise, NWE represents NWE, NWR0 and

NWR1 unless NWR0 and NWR1 are otherwise represented. ADDR represents A0 - A23

and/or A1 - A23.

Standard Read Protocol Standard read protocol implements a read cycle in which NRD and NWE are similar.

Both are active during the second half of the clock cycle. The first half of the clock cycle

allows time to ensure completion of the previous access as well as the output of address

and NCS before the read cycle begins.

During a standard read protocol, external memory access, NCS is set low and ADDR is

valid at the beginning of the access while NRD goes low only in the second half of the

master clock cycle to avoid bus conflict (see Figure 14). NWE is the same in both proto-

cols. NWE always goes low in the second half of the master clock cycle (see Figure 15).

Early Read Protocol Early read protocol provides more time for a read access from the memory by asserting

NRD at the beginning of the clock cycle. In the case of successive read cycles in the

same memory, NRD remains active continuously. Since a read cycle normally limits the

speed of operation of the external memory system, early read protocol can allow a

faster clock frequency to be used. However, an extra wait state is required in some

cases to avoid contentions on the external bus.

Early Read Wait State In early read protocol, an early read wait state is automatically inserted when an exter-

nal write cycle is followed by a read cycle to allow time for the write cycle to end before

the subsequent read cycle begins (see Figure 16). This wait state is generated in addi-

tion to any other programmed wait states (i.e. data float wait).

No wait state is added when a read cycle is followed by a write cycle, between consecu-

tive accesses of the same type or between external and internal memory accesses.

Early read wait states affect the external bus only. They do not affect internal bus timing.

Figure 14. Standard Read Protocol

ADDR

NCS

NWE

MCKI

NRD

28 AT91X40 Series

1354D–ATARM–08/02

Figure 15. Early Read Protocol

Figure 16. Early Read Wait State

Write Data Hold Time During write cycles in both protocols, output data becomes valid after the falling edge of

the NWE signal and remains valid after the rising edge of NWE, as illustrated in Figure

17. The external NWE waveform (on the NWE pin) is used to control the output data tim-

ing to guarantee this operation.

It is therefore necessary to avoid excessive loading of the NWE pins, which could delay

the write signal too long and cause a contention with a subsequent read cycle in stan-

dard protocol.

ADDR

NCS

NWE

MCKI

NRD

ADDR

NCS

NWE

MCKI

Write Cycle Early Read Wait Read Cycle

NRD

AT91X40 Series

1354D–ATARM–08/02

Figure 17. Data Hold Time

In early read protocol the data can remain valid longer than in standard read protocol

due to the additional wait cycle which follows a write access.

Wait States The EBI can automatically insert wait states. The different types of wait states are listed

below:

• Standard wait states

• Data float wait states

• External wait states

• Chip select change wait states

• Early read wait states (see “Read Protocols” )

Standard Wait States Each chip select can be programmed to insert one or more wait states during an access

on the corresponding device. This is done by setting the WSE field in the corresponding

EBI_CSR. The number of cycles to insert is programmed in the NWS field in the same

Below is the correspondence between the number of standard wait states programmed

and the number of cycles during which the NWE pulse is held low:

0 wait states1/2 cycle

1 wait state1 cycle

For each additional wait state programmed, an additional cycle is added.

ADDR

NWE

Data Output

MCK

30 AT91X40 Series

1354D–ATARM–08/02

Figure 18. One Wait State Access

Notes: 1. Early Read Protocol

2. Standard Read Protocol

Data Float Wait State Some memory devices are slow to release the external bus. For such devices it is nec-

essary to add wait states (data float waits) after a read access before starting a write

access or a read access to a different external memory.

The Data Float Output Time (tDF) for each external memory device is programmed in the

TDF field of the EBI_CSR register for the corresponding chip select. The value (0 - 7

clock cycles) indicates the number of data float waits to be inserted and represents the

time allowed for the data output to go high impedance after the memory is disabled.

Data float wait states do not delay internal memory accesses. Hence, a single access to

an external memory with long tDF will not slow down the execution of a program from

internal memory.

The EBI keeps track of the programmed external data float time during internal

accesses, to ensure that the external memory system is not accessed while it is still

busy.

Internal memory accesses and consecutive accesses to the same external memory do

not have added Data Float wait states.

ADDR

NCS

NWE

MCK

1 Wait State Access

NRD (1) (2)

AT91X40 Series

1354D–ATARM–08/02

Figure 19. Data Float Output Time

Notes: 1. Early Read Protocol

2. Standard Read Protocol

External Wait The NWAIT input can be used to add wait states at any time. NWAIT is active low and is

detected on the rising edge of the clock.

If NWAIT is low at the rising edge of the clock, the EBI adds a wait state and changes

neither the output signals nor its internal counters and state. When NWAIT is de-

asserted, the EBI finishes the access sequence.

The NWAIT signal must meet setup and hold requirements on the rising edge of the

clock.

Figure 20. External Wait

Notes: 1. Early Read Protocol

2. Standard Read Protocol

ADDR

NRD

D0 - D15

MCK

tDF

(1) (2)

NCS

ADDR

NCS

NWE

MCK

NRD (1) (2)

NWAIT

32 AT91X40 Series

1354D–ATARM–08/02

Additional constraints are applicable to the AT91R40807, the AT91M40807 and the

AT91 40800. The behavior of the EBI is correct when NWAIT is asserted during an

external memory access:

• When NWAIT is asserted before the first rising edge of MCKI

• When NWAIT is de-asserted and at least one standard wait state remains to be

executed

These constraints are not applicable to the AT91R40008.

Chip Select Change Wait

States

A chip select wait state is automatically inserted when consecutive accesses are made

to two different external memories (if no wait states have already been inserted). If any

wait states have already been inserted, (e.g., data float wait) then none are added.

Figure 21. Chip Select Wait

Notes: 1. Early Read Protocol

2. Standard Read Protocol

NCS1

NCS2

MCK

Mem 1 Chip Select Wait Mem 2

NRD

NWE

(1) (2)

AT91X40 Series

1354D–ATARM–08/02

Memory Access

Waveforms

ures 22 throu

h 25 show exam

les of the two alternative

rotocols for external mem-

read access.

Figure 22. Standard Read Protocol without tDF

Read Mem 1 Write Mem 1 Read Mem 1 Read Mem 2 Write Mem 2 Read Mem 2

Chip Select

Change Wait

A0 - A23

NRD

NWE

NCS1

NCS2

D0 - D15 (Mem 1)

D0 - D15 (Mem 2)

D0 - D15 (AT91)

MCK

tWHDX tWHDX

34 AT91X40 Series

1354D–ATARM–08/02

Figure 23. Early Read Protocol Without tDF

Read

Mem 1

Write

Mem 1

A0 - A23

NRD

NWE

NCS1

NCS2

D0 - D15 (Mem 1)

D0 - D15 (Mem 2)

D0- D15 (AT91)

MCK

Early Read

Wait Cycle

Read

Mem 1

Read

Mem 2

Write

Mem 2

Early Read

Wait Cycle

Read

Mem 2

Chip Select

Change Wait

Long tWHDX Long tWHDX

AT91X40 Series

1354D–ATARM–08/02

Figure 24. Standard Read Protocol with tDF

Read Mem 1

Write

Mem 1

A0 - A23

NRD

NWE

NCS1

NCS2

D0 - D15 (Mem 1)

D0 - D15 (Mem 2)

D0 - D15 (AT91)

MCK

Data

Float Wait

Read Mem 1

Data

Float Wait

Read

Mem 2 Read Mem 2

Data

Float Wait

Write

Mem 2

Write

Mem 2

Write

Mem 2

tWHDX

tDF tDF

tDF

36 AT91X40 Series

1354D–ATARM–08/02

Figure 25. Early Read Protocol With tDF

Read Mem 1

Write

Mem 1

A0 - A23

NRD

NWE

NCS1

NCS2

D0 - D15 (Mem 1)

D0 - D15 (Mem 2)

D0 - D15 (AT91)

MCK

Data

Float Wait

Early

Read Wait Read Mem 1

Data

Float Wait

Read

Mem 2 Read Mem 2

Data

Float Wait

Write

Mem 2

Write

Mem 2

Write

Mem 2

tDF tDF

tDF

tWHDX

AT91X40 Series

1354D–ATARM–08/02

ures 26 throu

h 32 show the timin

cles and wait states for read and write access

to the various AT91X40 Series external memor

devices. The confi

urations described

are shown in the followin

table:

Table 5. Memory Access Waveforms

Figure Number Number of Wait States Bus Width Size of Data Transfer

26 0 16 Word

27 1 16 Word

28 1 16 Half-word

29 0 8 Word

30 1 8 Half-word

31 1 8 Byte

32 0 16 Byte

38 AT91X40 Series

1354D–ATARM–08/02

Figure 26. 0 Wait States, 16-bit Bus Width, Word Transfer

ADDR ADDR+1

B2B1 B

4 B3

B4 B3 B2 B1

MCK

A1 - A23

NCS

NRD

D0 - D15

Internal Bus X X B2 B1

READ ACCESS

NRD

B2 B1B4 B3 D0 - D15

WRITE ACCESS

NWE

B2 B1 B4 B3 D0 - D15

NLB

NUB

· Standard Protocol

· Early Protocol

· Byte Write/

Byte Select Option

AT91X40 Series

1354D–ATARM–08/02

Figure 27. 1 Wait, 16-bit Bus Width, Word Transfer

ADDR ADDR+1

B2B1

B4 B3

X X B2 B1B4 B3 B2 B1

1 Wait State 1 Wair State

MCK

A1 - A23

NCS

NRD

D0 - D15

Internal Bus

WRITE ACCESS

READ ACCESS

NRD

D0 - D15

· Standard Protocol

· Early Protocol

B4B3

NWE

D0 - D15 B2B1B4B3

NLB

NUB

B2 B1

· Byte Write/

Byte Select Option

40 AT91X40 Series

1354D–ATARM–08/02

Figure 28. 1 Wait State, 16-bit Bus Width, Half-word Transfer

B2 B1

1 Wait State

MCK

A1 - A23

NCS

NRD

D0 - D15

Internal Bus X X B2 B1

READ ACCESS

· Standard Protocol

NLB

NUB

· Early Protocol

B2 B1

NRD

D0 - D15

WRITE ACCESS

NWE

B2 B1

D0 - D15

· Byte Write/

Byte Select Option

AT91X40 Series

1354D–ATARM–08/02

Figure 29. 0 Wait States, 8-bit Bus Width, Word Transfer

ADDR ADDR+1

X B1

X B3 B2 B1

MCK

A0 - A23

NCS

NRD

D0-D15

Internal Bus

ADDR+2 ADDR+3

X X B2 B1

X B2

X X X B1

X B3X B4

B4 B3 B2 B1

READ ACCESS

· Standard Protocol

· Early Protocol

NRD

X B1

D0 - D15 X B2 X B3X B4

WRITE ACCESS

NWR0

NWR1

X B1

D0 - D15 X B2 X B3X B4

42 AT91X40 Series

1354D–ATARM–08/02

Figure 30. 1 Wait State, 8-bit Bus Width, Half-word Transfer

ADDR

X B1

1 Wait State

MCK

A0 - A23

NCS

NRD

D0 - D15

Internal Bus

ADDR+1

1 Wait State

X X B2 B1

X B2

X X X B1

READ ACCESS

· Standard Protocol

· Early Protocol

NRD

X B1

D0 - D15 X B2

WRITE ACCESS

NWR0

X B1

D0 - D15 X B2

NWR1

AT91X40 Series

1354D–ATARM–08/02

Figure 31. 1 Wait State, 8-bit Bus Width, Byte Transfer

XB1

1 Wait State

MCK

A0 - A23

NCS

NRD

D0 - D15

Internal Bus X X X B1

READ ACCESS

· Standard Protocol

· Early Protocol

D0 - D15 X B1

WRITE ACCESS

NWR0

D0 - D15 X B1

NRD

NWR1

44 AT91X40 Series

1354D–ATARM–08/02

Figure 32. 0 Wait States, 16-bit Bus Width, Byte Transfer

MCK

A1 - A23

NCS

NWR1

D0 - D15 X B1 B2X

ADDR X X X 0 ADDR X X X 0

ADDR X X X 0 ADDR X X X 1

Internal Address

Internal Bus X X X B1 X X B2X

NLB

NUB

READ ACCESS

· Standard Protocol

NRD

· Early Protocol

NRD

D0 - D15 XB1B2X

WRITE ACCESS

NWR0

D0 - D15 B1B1B2B2

· Byte Write Option

· Byte Select Option

NWE

AT91X40 Series

1354D–ATARM–08/02

EBI User Interface The EBI is programmed using the registers listed in the table below. The Remap Control

The Memory Control Register (EBI_MCR) is used to program the number of active chip

selects and data read protocol. Eight Chip Select Registers (EBI_CSR0 to EBI_CSR7)

are used to program the parameters for the individual external memories. Each

EBI_CSR must be programmed with a different base address, even for unused chip

selects.

Base Address: 0xFFE00000 (Code Label EBI_BASE)

Notes: 1. 8-bit boot (if BMS is detected high)

2. 16-bit boot (if BMS is detected low)

Table 6. EBI Memory Map

Offset Register Name Access Reset State

0x00 Chip Select Register 0 EBI_CSR0 Read/Write 0x0000203E(1)

0x0000203D(2)

0x04 Chip Select Register 1 EBI_CSR1 Read/Write 0x10000000

0x08 Chip Select Register 2 EBI_CSR2 Read/Write 0x20000000

0x0C Chip Select Register 3 EBI_CSR3 Read/Write 0x30000000

0x10 Chip Select Register 4 EBI_CSR4 Read/Write 0x40000000

0x14 Chip Select Register 5 EBI_CSR5 Read/Write 0x50000000

0x18 Chip Select Register 6 EBI_CSR6 Read/Write 0x60000000

0x1C Chip Select Register 7 EBI_CSR7 Read/Write 0x70000000

0x20 Remap Control Register EBI_RCR Write only –

0x24 Memory Control

46 AT91X40 Series

1354D–ATARM–08/02

EBI Chip Select Register

Access Type: Read/Write

Reset Value: See Table 6

Absolute Address:0xFFE00000 - 0xFFE0001C

Offset: 0x00 - 0x1C

• DBW: Data Bus Width

• NWS: Number of Wait States

This field is valid only if WSE is set.

• WSE: Wait State Enable (Code Label EBI_WSE)

0 = Wait state generation is disabled. No wait states are inserted.

1 = Wait state generation is enabled.

31 30 29 28 27 26 25 24

23 22 21 20 19 18 17 16

BA – – – –

15 14 13 12 11 10 9 8

––

CSEN BAT TDF PAGES

76543210

PAGES –WSE NWS DBW

DBW Data Bus Width

Code Label

EBI_DBW

0 0 Reserved –

0 1 16-bit data bus width EBI_DBW_16

1 0 8-bit data bus width EBI_DBW_8

11Reserved –

NWS Number of Standard Wait States

Code Label

EBI_NWS

000 1 EBI_NWS_1

001 2 EBI_NWS_2

010 3 EBI_NWS_3

011 4 EBI_NWS_4

100 5 EBI_NWS_5

101 6 EBI_NWS_6

110 7 EBI_NWS_7

111 8 EBI_NWS_8

AT91X40 Series

1354D–ATARM–08/02

• PAGES: Page Size

• TDF: Data Float Output Time

• BAT: Byte Access Type

• CSEN: Chip Select Enable (Code Label EBI_CSEN)

0 = Chip select is disabled.

1 = Chip select is enabled.

• BA: Base Address (Code Label EBI_BA)

These bits contain the highest bits of the base address. If the page size is larger than 1M byte, the unused bits of the base

address are ignored by the EBI decoder.

PAGES Page Size Active Bits in Base Address

Code Label

EBI_PAGES

0 0 1M Byte 12 Bits (31 - 20) EBI_PAGES_1M

0 1 4M Bytes 10 Bits (31 - 22) EBI_PAGES_4M

1 0 16M Bytes 8 Bits (31 - 24) EBI_PAGES_16M

1 1 64M Bytes 6 Bits (31 - 26) EBI_PAGES_64M

TDF Number of Cycles Added after the Transfer

Code Label

EBI_TDF

000 0 EBI_TDF_0

001 1 EBI_TDF_1

010 2 EBI_TDF_2

011 3 EBI_TDF_3

100 4 EBI_TDF_4

101 5 EBI_TDF_5

110 6 EBI_TDF_6

111 7 EBI_TDF_7

BAT Selected BAT

Code Label

EBI_BAT

0 Byte-write access type. EBI_BAT_BYTE_WRITE

1 Byte-select access type. EBI_BAT_BYTE_SELECT

48 AT91X40 Series

1354D–ATARM–08/02

EBI Remap Control Register

Access Type: Write Only

Absolute Address:0xFFE00020

Offset: 0x20

• RCB: Remap Command Bit (Code Label EBI_RCB)

0 = No effect.

1 = Cancels the remapping (performed at reset) of the page zero memory devices.

31 30 29 28 27 26 25 24

––––––––

23 22 21 20 19 18 17 16

––––––––

15 14 13 12 11 10 9 8

––––––––

76543210

–––––––

RCB

AT91X40 Series

1354D–ATARM–08/02

EBI Memory Control Register

Access Type: Read/Write

Reset Value: 0

Absolute Address:0xFFE00024

Offset: 0x24

• ALE: Address Line Enable

This field determines the number of valid address lines and the number of valid chip select lines.

• DRP: Data Read Protocol

31 30 29 28 27 26 25 24

––––––––

23 22 21 20 19 18 17 16

––––––––

15 14 13 12 11 10 9 8

––––––––

76543210

–––

DRP –ALE

ALE Valid Address Bits Maximum Addressable Space Valid Chip Select

Code Label

EBI_ALE

0 X X A20, A21, A22, A23 16M Bytes None EBI_ALE_16M

1 0 0 A20, A21, A22 8M Bytes CS4 EBI_ALE_8M

1 0 1 A20, A21 4M Bytes CS4, CS5 EBI_ALE_4M

1 1 0 A20 2M Bytes CS4, CS5, CS6 EBI_ALE_2M

1 1 1 None 1M Byte CS4, CS5, CS6, CS7 EBI_ALE_1M

DRP Selected DRP

Code Label

EBI_DRP

0 Standard read protocol for all external memory devices enabled EBI_DRP_STANDARD

1 Early read protocol for all external memory devices enabled EBI_DRP_EARLY

50 AT91X40 Series

1354D–ATARM–08/02

PS: Power-saving The AT91X40 Series’ Power-saving feature enables optimization of power consumption.

The PS controls the CPU and Peripheral Clocks. One control register (PS_CR) enables

the user to stop the ARM7TDMI Clock and enter Idle Mode. One set of registers with a

set/clear mechanism enables and disables the peripheral clocks individually.

The ARM7TDMI clock is enabled after a reset and is automatically re-enabled by any

enabled interrupt in the Idle Mode.

Peripheral Clocks The clock of each peripheral integrated in the AT91X40 Series can be individually

enabled and disabled by writing to the Peripheral Clock Enable (PS_PCER) and Periph-

eral Clock Disable Registers (PS_PCDR). The status of the peripheral clocks can be

read in the Peripheral Clock Status Register (PS_PCSR).

When a peripheral clock is disabled, the clock is immediately stopped. When the clock is

re-enabled, the peripheral resumes action where it left off.

To avoid data corruption or erroneous behavior of the system, the system software only

disables the clock after all programmed peripheral operations have finished.

The peripheral clocks are automatically enabled after a reset.

The bits that control the peripheral clocks are the same as those that control the Inter-

rupt Sources in the AIC.

AT91X40 Series

1354D–ATARM–08/02

PS User Interface

Base Address: 0xFFFF4000 (Code Label PS_BASE)

Table 7. PS Memory Map

Offset Register Name Access Reset State

0x00 Control Register PS_CR Write Only –

0x04 Peripheral Clock Enable Register PS_PCER Write Only –

0x08 Peripheral Clock Disable Register PS_PCDR Write Only –

0x0C Peripheral Clock Status Register PS_PCSR Read Only 0x17C

52 AT91X40 Series

1354D–ATARM–08/02

PS Control Register

Name: PS_CR

Access: Write Only

Offset: 0x00

• CPU: CPU Clock Disable

0 = No effect.

1 = Disables the CPU clock.

The CPU clock is re-enabled by any enabled interrupt or by hardware reset.

31 30 29 28 27 26 25 24

––––––––

23 22 21 20 19 18 17 16

––––––––

15 14 13 12 11 10 9 8

––––––––

76543210

–––––––

CPU

AT91X40 Series

1354D–ATARM–08/02

PS Peripheral Clock Enable Register

Name: PS_PCER

Access: Write Only

Offset:0x04

• US0: USART 0 Clock Enable

0 = No effect.

1 = Enables the USART 0 clock.

• US1: USART 1 Clock Enable

0 = No effect.

1 = Enables the USART 1 clock.

• TC0: Timer Counter 0 Clock Enable

0 = No effect.

1 = Enables the Timer Counter 0 clock.

• TC1: Timer Counter 1 Clock Enable

0 = No effect.

1 = Enables the Timer Counter 1 clock.

• TC2: Timer Counter 2 Clock Enable

0 = No effect.

1 = Enables the Timer Counter 2 clock.

• PIO: Parallel IO Clock Enable

0 = No effect.

1 = Enables the Parallel IO clock.

31 30 29 28 27 26 25 24

––––––––

23 22 21 20 19 18 17 16

––––––––

15 14 13 12 11 10 9 8

–––––––

PIO

76543210

–TC2 TC1 TC0 US1 US0 ––

54 AT91X40 Series

1354D–ATARM–08/02

PS Peripheral Clock Disable Register

Name: PS_PCDR

Access:Write Only

Offset:0x08

• US0: USART 0 Clock Disable

0 = No effect.

1 = Disables the USART 0 clock.

• US1: USART 1 Clock Disable

0 = No effect.

1 = Disables the USART 1 clock.

• TC0: Timer Counter 0 Clock Disable

0 = No effect.

1 = Disables the Timer Counter 0 clock.

• TC1: Timer Counter 1 Clock Disable

0 = No effect.

1 = Disables the Timer Counter 1 clock.

• TC2: Timer Counter 2 Clock Disable

0 = No effect.

1 = Disables the Timer Counter 2 clock.

• PIO: Parallel IO Clock Disable

0 = No effect.

1 = Disables the Parallel IO clock.

31 30 29 28 27 26 25 24

––––––––

23 22 21 20 19 18 17 16

––––––––

15 14 13 12 11 10 9 8

–––––––

PIO

76543210

–TC2 TC1 TC0 US1 US0 ––

AT91X40 Series

1354D–ATARM–08/02

PS Peripheral Clock Status Register

Name: PS_PCSR

Access: Read Only

Reset Value: 0x17C

Offset:0x0C

• US0: USART 0 Clock Status

0 = USART 0 clock is disabled.

1 = USART 0 clock is enabled.

• US1: USART 1 Clock Status

0 = USART 1 clock is disabled.

1 = USART 1 clock is enabled.

• TC0: Timer Counter 0 Clock Status

0 = Timer Counter 0 clock is disabled.

1 = Timer Counter 0 clock is enabled.

• TC1: Timer Counter 1 Clock Status

0 = Timer Counter 1 clock is disabled.

1 = Timer Counter 1 clock is enabled.

• TC2: Timer Counter 2 Clock Status

0 = Timer Counter 2 clock is disabled.

1 = Timer Counter 2 clock is enabled.

• PIO: Parallel IO Clock Status

0 = Parallel IO clock is disabled.

1 = Parallel IO clock is enabled.

31 30 29 28 27 26 25 24

––––––––

23 22 21 20 19 18 17 16

––––––––

15 14 13 12 11 10 9 8

–––––––

PIO

76543210

–TC2 TC1 TC0 US1 US0 ––

56 AT91X40 Series

1354D–ATARM–08/02

AIC: Advanced

Interrupt Controller

The AT91X40 Series has an 8-level priority, individually maskable, vectored interrupt

controller. This feature substantially reduces the software and real-time overhead in

handling internal and external interrupts.

The interrupt controller is connected to the NFIQ (fast interrupt request) and the NIRQ

(standard interrupt request) inputs of the ARM7TDMI processor. The processor’s NFIQ

line can only be asserted by the external fast interrupt request input: FIQ. The NIRQ line

can be asserted by the interrupts generated by the on-chip peripherals and the external

interrupt request lines: IRQ0 to IRQ2.

The 8-level priority encoder allows the customer to define the priority between the differ-

ent NIRQ interrupt sources.

Internal sources are programmed to be level sensitive or edge triggered. External

sources can be programmed to be positive or negative edge triggered or high- or low-

level sensitive.

The interrupt sources are listed in Table 8 and the AIC programmable registers in Table

Figure 33. Interrupt Controller Block Diagram

Note: After a hardware reset, the AIC pins are controlled by the PIO Controller. They must be configured to be controlled by the

peripheral before being used.

Control

Logic

Memorization

Memorization Priority

Controller

NIRQ

Manager

NFIQ

Manager

FIQ Source

Advanced Peripheral

Bus (APB)

Internal Interrupt Sources

External Interrupt Sources

ARM7TDMI

Core

NFIQ

NIRQ

AT91X40 Series

1354D–ATARM–08/02

Note: 1. Reserved interrupt sources are not available. Corresponding registers must not be used and read 0.

Table 8. AIC Interrupt Sources

Interrupt Source (1) Interrupt Name Interrupt Description

0 FIQ Fast Interrupt

1 SWIRQ Software Interrupt

2 US0IRQ USART Channel 0 interrupt

3 US1IRQ USART Channel 1 interrupt

4 TC0IRQ Timer Channel 0 interrupt

5 TC1IRQ Timer Channel 1 interrupt

6 TC2IRQ Timer Channel 2 interrupt

7 WDIRQ Watchdog interrupt

8 PIOIRQ Parallel I/O Controller interrupt

9–Reserved

10 – Reserved

11 – Reserved

12 – Reserved

13 – Reserved

14 – Reserved

15 – Reserved

16 IRQ0 External interrupt 0

17 IRQ1 External interrupt 1

18 IRQ2 External interrupt 2

19 – Reserved

20 – Reserved

21 – Reserved

22 – Reserved

23 – Reserved

24 – Reserved

25 – Reserved

26 – Reserved

27 – Reserved

28 – Reserved

29 – Reserved

30 – Reserved

31 – Reserved

58 AT91X40 Series

1354D–ATARM–08/02

Hardware Interrupt

Vectoring

The hardware interrupt vectoring reduces the number of instructions to reach the inter-

rupt handler to only one. By storing the following instruction at address 0x00000018, the

processor loads the program counter with the interrupt handler address stored in the

AIC_IVR register. Execution is then vectored to the interrupt handler corresponding to

the current interrupt.

ldr PC,[PC,# - &F20]

The current interrupt is the interrupt with the highest priority when the Interrupt Vector

stored in the Source Vector Register (AIC_SVR) of the current interrupt. Each interrupt

source has its corresponding AIC_SVR. In order to take advantage of the hardware

interrupt vectoring it is necessary to store the address of each interrupt handler in the

corresponding AIC_SVR, at system initialization.

Priority Controller The NIRQ line is controlled by an 8-level priority encoder. Each source has a program-

mable priority level of 7 to 0. Level 7 is the highest priority and level 0 the lowest.

When the AIC receives more than one unmasked interrupt at a time, the interrupt with

the highest priority is serviced first. If both interrupts have equal priority, the interrupt

with the lowest interrupt source number (see table 8) is serviced first.

The current priority level is defined as the priority level of the current interrupt at the time

the register AIC_IVR is read (the interrupt which will be serviced).

In the case when a higher priority unmasked interrupt occurs while an interrupt already

exists, there are two possible outcomes depending on whether the AIC_IVR has been

read.

• If the NIRQ line has been asserted but the AIC_IVR has not been read, then the

processor will read the new higher priority interrupt handler address in the AIC_IVR

• If the processor has already read the AIC_IVR then the NIRQ line is reasserted.

When the processor has authorized nested interrupts to occur and reads the

AIC_IVR again, it reads the new, higher priority interrupt handler address. At the

same time the current priority value is pushed onto a first-in last-out stack and the

current priority is updated to the higher priority.

When the end of interrupt command register (AIC_EOICR) is written the current inter-

rupt level is updated with the last stored interrupt level from the stack (if any). Hence at

the end of a higher priority interrupt, the AIC returns to the previous state corresponding

to the preceding lower priority interrupt which had been interrupted.

Interrupt Handling The interrupt handler must read the AIC_IVR as soon as possible. This de-asserts the

NIRQ request to the processor and clears the interrupt in case it is programmed to be

edge triggered. This permits the AIC to assert the NIRQ line again when a higher priority

unmasked interrupt occurs.

At the end of the interrupt service routine, the end of interrupt command register

(AIC_EOICR) must be written. This allows pending interrupts to be serviced.

Interrupt Masking Each interrupt source, including FIQ, can be enabled or disabled using the command

registers AIC_IECR and AIC_IDCR. The interrupt mask can be read in the read only

AT91X40 Series

1354D–ATARM–08/02

Interrupt Clearing and

Setting

All interrupt sources which are programmed to be edge triggered (including FIQ) can be

individually set or cleared by respectively writing to the registers AIC_ISCR and

AIC_ICCR. This function of the interrupt controller is available for auto-test or software

debug purposes.

Fast Interrupt Request The external FIQ line is the only source which can raise a fast interrupt request to the

processor. Therefore, it has no priority controller.

The external FIQ line can be programmed to be positive or negative edge triggered or

high- or low-level sensitive in the AIC_SMR0 register.

The fast interrupt handler address can be stored in the AIC_SVR0 register. The value

written into this register is available by reading the AIC_FVR register when an FIQ inter-

rupt is raised. By storing the following instruction at address 0x0000001C, the processor

will load the program counter with the interrupt handler address stored in the AIC_FVR

ldr PC,[PC,# -&F20]

Alternatively the interrupt handler can be stored starting from address 0x0000001C as

described in the ARM7TDMI datasheet.

Software Interrupt Interrupt source 1 of the advanced interrupt controller is a software interrupt. It must be

programmed to be edge triggered in order to set or clear it by writing to the AIC_ISCR

and AIC_ICCR.

This is totally independent of the SWI instruction of the ARM7TDMI processor.

Spurious Interrupt When the AIC asserts the NIRQ line, the ARM7TDMI enters IRQ Mode and the interrupt

handler reads the IVR. It may happen that the AIC de-asserts the NIRQ line after the

core has taken into account the NIRQ assertion and before the read of the IVR.

This behavior is called a Spurious Interrupt.

The AIC is able to detect these Spurious Interrupts and returns the Spurious Vector

when the IVR is read. The Spurious Vector can be programmed by the user when the

vector table is initialized.

A spurious interrupt may occur in the following cases:

• With any sources programmed to be level sensitive, if the interrupt signal of the AIC

input is de-asserted at the same time as it is taken into account by the ARM7TDMI.

• If an interrupt is asserted at the same time as the software is disabling the

corresponding source through AIC_IDCR (this can happen due to the pipelining of

the ARM core).

The same mechanism of spurious interrupt occurs if the ARM7TDMI reads the IVR

(application software or ICE) when there is no interrupt pending. This mechanism is also

valid for the FIQ interrupts.

Once the AIC enters the spurious interrupt management, it asserts neither the NIRQ nor

the NFIQ lines to the ARM7TDMI as long as the spurious interrupt is not acknowledged.

Therefore, it is mandatory for the Spurious Interrupt Service Routine to acknowledge the

“spurious” behavior by writing to the AIC_EOICR (End of Interrupt) before returning to

the interrupted software. It also can perform other operation(s), e.g., trace possible

undesirable behavior.

60 AT91X40 Series

1354D–ATARM–08/02

Protect Mode The Protect Mode permits reading of the Interrupt Vector Register without performing

the associated automatic operations. This is necessary when working with a debug

system.

When a Debug Monitor or an ICE reads the AIC User Interface, the IVR could be read.

This would have the following consequences in Normal Mode.

• If an enabled interrupt with a higher priority than the current one is pending, it would

be stacked

• If there is no enabled pending interrupt, the spurious vector would be returned.

In either case, an End of Interrupt command would be necessary to acknowledge and to

restore the context of the AIC. This operation is generally not performed by the debug

system. Hence the debug system would become strongly intrusive, and could cause the

application to enter an undesired state.

This is avoided by using Protect Mode.

The Protect Mode is enabled by setting the AIC bit in the SF Protect Mode Register (see

“SF: Special Function Registers” on page 94).

When Protect Mode is enabled, the AIC performs interrupt stacking only when a write

access is performed on the AIC_IVR. Therefore, the Interrupt Service Routines must

write (arbitrary data) to the AIC_IVR just after reading it.

The new context of the AIC, including the value of the Interrupt Status Register

(AIC_ISR), is updated with the current interrupt only when IVR is written.

An AIC_IVR read on its own (e.g. by a debugger), modifies neither the AIC context nor

the AIC_ISR.

Extra AIC_IVR reads performed in between the read and the write can cause unpredict-

able results. Therefore, it is strongly recommended not to set a breakpoint between

these two actions, nor to stop the software.

The debug system must not write to the AIC_IVR as this would cause undesirable

effects.

The following table shows the main steps of an interrupt and the order in which they are

performed according to the mode:

Notes: 1. NIRQ de-assertion and automatic interrupt clearing if the source is programmed as

level sensitive.

2. Software that has been written and debugged using Protect Mode will run correctly in

Normal Mode without modification. However, in Normal Mode the AIC_IVR write has

no effect and can be removed to optimize the code.

Action Normal Mode Protect Mode

Calculate active interrupt (higher than current or spurious) Read AIC_IVR Read AIC_IVR

Determine and return the vector of the active interrupt Read AIC_IVR Read AIC_IVR

Memorize interrupt Read AIC_IVR Read AIC_IVR

Push on internal stack the current priority level Read AIC_IVR Write AIC_IVR

Acknowledge the interrupt (1) Read AIC_IVR Write AIC_IVR

No effect(2) Write AIC_IVR –

AT91X40 Series

1354D–ATARM–08/02

AIC User Interface

• Base Address: 0xFFFFF000 (Code Label AIC_BASE)

Note: The reset value of this register depends on the level of the External IRQ lines. All other sources are cleared at reset.

Table 9. AIC Memory Map

Offset Register Name Access Reset State

0x000 Source Mode Register 0 AIC_SMR0 Read/Write 0

0x004 Source Mode Register 1 AIC_SMR1 Read/Write 0

– – – Read/Write 0

0x07C Source Mode Register 31 AIC_SMR31 Read/Write 0

0x080 Source Vector Register 0 AIC_SVR0 Read/Write 0

0x084 Source Vector Register 1 AIC_SVR1 Read/Write 0

– – – Read/Write 0

0x0FC Source Vector Register 31 AIC_SVR31 Read/Write 0

0x100 IRQ Vector Register AIC_IVR Read Only 0

0x104 FIQ Vector Register AIC_FVR Read Only 0

0x108 Interrupt Status Register AIC_ISR Read Only 0

0x10C Interrupt Pending Register AIC_IPR Read Only (see Note 1)

0x110 Interrupt Mask Register AIC_IMR Read Only 0

0x114 Core Interrupt Status Register AIC_CISR Read Only 0

0x118 Reserved – – –

0x11C Reserved – – –

0x120 Interrupt Enable Command Register AIC_IECR Write Only –

0x124 Interrupt Disable Command Register AIC_IDCR Write Only –

0x128 Interrupt Clear Command Register AIC_ICCR Write Only –

0x12C Interrupt Set Command Register AIC_ISCR Write Only –

0x130 End of Interrupt Command Register AIC_EOICR Write Only –

0x134 Spurious Vector Register AIC_SPU Read/Write 0

62 AT91X40 Series

1354D–ATARM–08/02

AIC Source Mode Register

Access Type: Read/Write

Reset Value: 0

Offset: 0x000 - 0x07C

• PRIOR: Priority Level (Code Label AIC_PRIOR)

Program the priority level for all sources except source 0 (FIQ).

The priority level can be between 0 (lowest) and 7 (highest).

The priority level is not used for the FIQ, in the SMR0.

• SRCTYPE: Interrupt Source Type

Program the input to be positive or negative level sensitive or positive or negative edge triggered.

The active level or edge is not programmable for the internal sources.

31 30 29 28 27 26 25 24

––––––––

23 22 21 20 19 18 17 16

––––––––

15 14 13 12 11 10 9 8

––––––––

76543210

–SRCTYPE –– PRIOR

SRCTYPE External Sources

Code Label

AIC_SRCTYPE

0 0 Low Level Sensitive AIC_SRCTYPE_EXT_LOW_LEVEL

0 1 Negative Edge Triggered AIC_SRCTYPE_EXT_NEGATIVE_EDGE

1 0 High Level Sensitive AIC_SRCTYPE_EXT_HIGH_LEVEL

1 1 Positive Edge Triggered AIC_SRCTYPE_EXT_POSITIVE_EDGE

SRCTYPE Internal Sources

Code Label

AIC_SRCTYPE

x 0 Level Sensitive AIC_SRCTYPE_INT_LEVEL

x 1 Edge Triggered AIC_SRCTYPE_INT_EDGE

AT91X40 Series

1354D–ATARM–08/02

AIC Source Vector Register

Access Type: Read/Write

Reset Value:0

Offset: 0x080 - 0x0FC

• VECTOR: Interrupt Handler Address

The user may store in these registers the addresses of the corresponding handler for each interrupt source.

31 30 29 28 27 26 25 24

VECTOR

23 22 21 20 19 18 17 16

VECTOR

15 14 13 12 11 10 9 8

VECTOR

76543210

VECTOR

64 AT91X40 Series

1354D–ATARM–08/02

AIC Interrupt Vector Register

Access Type: Read Only

Reset Value:0

Offset: 0x100

• IRQV: Interrupt Vector Register

The IRQ Vector Register contains the vector programmed by the user in the Source Vector Register corresponding to the

current interrupt.

The Source Vector Register (1 to 31) is indexed using the current interrupt number when the Interrupt Vector Register is

read.

When there is no current interrupt, the IRQ Vector Register reads 0.

AIC FIQ Vector Register

Access Type: Read Only

Reset Value:0

Offset: 0x104

• FIQV: FIQ Vector Register

The FIQ Vector Register contains the vector programmed by the user in the Source Vector Register 0 which corresponds to

FIQ.

31 30 29 28 27 26 25 24

IRQV

23 22 21 20 19 18 17 16

IRQV

15 14 13 12 11 10 9 8

IRQV

76543210

IRQV

31 30 29 28 27 26 25 24

FIQV

23 22 21 20 19 18 17 16

FIQV

15 14 13 12 11 10 9 8

FIQV

76543210

FIQV

AT91X40 Series

1354D–ATARM–08/02

AIC Interrupt Status Register

Access Type: Read Only

Reset Value:0

Offset: 0x108

• IRQID: Current IRQ Identifier (Code Label AIC_IRQID)

The Interrupt Status Register returns the current interrupt source number.

AIC Interrupt Pending Register

Access Type: Read Only

Reset Value:0

Offset: 0x10C

• Interrupt Pending

0 = Corresponding interrupt is inactive.

1 = Corresponding interrupt is pending.

31 30 29 28 27 26 25 24

––––––––

23 22 21 20 19 18 17 16

––––––––

15 14 13 12 11 10 9 8

––––––––

76543210

––– IRQID

31 30 29 28 27 26 25 24

––––––––

23 22 21 20 19 18 17 16

–––––

IRQ2 IRQ1 IRQ0

15 14 13 12 11 10 9 8

–––––––

PIOIRQ

76543210

WDIRQ TC2IRQ TC1IRQ TC0IRQ US1IRQ US0IRQ SWIRQ FIQ

66 AT91X40 Series

1354D–ATARM–08/02

AIC Interrupt Mask Register

Access Type: Read Only

Reset Value:0

Offset: 0x110

• Interrupt Mask

0 = Corresponding interrupt is disabled.

1 = Corresponding interrupt is enabled.

31 30 29 28 27 26 25 24

––––––––

23 22 21 20 19 18 17 16

–––––

IRQ2 IRQ1 IRQ0

15 14 13 12 11 10 9 8

–––––––

PIOIRQ

76543210

WDIRQ TC2IRQ TC1IRQ TC0IRQ US1IRQ US0IRQ SWIRQ FIQ

AT91X40 Series

1354D–ATARM–08/02

AIC Core Interrupt Status Register

Access Type: Read Only

Reset Value:0

Offset: 0x114

• NFIQ: NFIQ Status (Code Label AIC_NFIQ)

0 = NFIQ line inactive.

1 = NFIQ line active.

• NIRQ: NIRQ Status (Code Label AIC_NIRQ)

0 = NIRQ line inactive.

1 = NIRQ line active.

31 30 29 28 27 26 25 24

––––––––

23 22 21 20 19 18 17 16

––––––––

15 14 13 12 11 10 9 8

––––––––

76543210

––––––

NIRQ NFIQ

68 AT91X40 Series

1354D–ATARM–08/02

AIC Interrupt Enable Command Register

Access Type:Write Only

Offset: 0x120

• Interrupt Enable

0 = No effect.

1 = Enables corresponding interrupt.

AIC Interrupt Disable Command Register

Access Type:Write Only

Offset: 0x124

• Interrupt Disable

0 = No effect.

1 = Disables corresponding interrupt.

31 30 29 28 27 26 25 24

––––––––

23 22 21 20 19 18 17 16

–––––

IRQ2 IRQ1 IRQ0

15 14 13 12 11 10 9 8

–––––––

PIOIRQ

76543210

WDIRQ TC2IRQ TC1IRQ TC0IRQ US1IRQ US0IRQ SWIRQ FIQ

31 30 29 28 27 26 25 24

––––––––

23 22 21 20 19 18 17 16

–––––

IRQ2 IRQ1 IRQ0

15 14 13 12 11 10 9 8

–––––––

PIOIRQ

76543210

WDIRQ TC2IRQ TC1IRQ TC0IRQ US1IRQ US0IRQ SWIRQ FIQ

AT91X40 Series

1354D–ATARM–08/02

AIC Interrupt Clear Command Register

Access Type:Write Only

Offset: 0x128

• Interrupt Clear

0 = No effect.

1 = Clears corresponding interrupt.

AIC Interrupt Set Command Register

Access Type:Write Only

Offset: 0x12C

• Interrupt Set

0 = No effect.

1 = Sets corresponding interrupt.

31 30 29 28 27 26 25 24

––––––––

23 22 21 20 19 18 17 16

–––––

IRQ2 IRQ1 IRQ0

15 14 13 12 11 10 9 8

–––––––

PIOIRQ

76543210

WDIRQ TC2IRQ TC1IRQ TC0IRQ US1IRQ US0IRQ SWIRQ FIQ

31 30 29 28 27 26 25 24

––––––––

23 22 21 20 19 18 17 16

–––––

IRQ2 IRQ1 IRQ0

15 14 13 12 11 10 9 8

–––––––

PIOIRQ

76543210

WDIRQ TC2IRQ TC1IRQ TC0IRQ US1IRQ US0IRQ SWIRQ FIQ

70 AT91X40 Series

1354D–ATARM–08/02

AIC End of Interrupt Command Register

Access Type:Write Only

Offset: 0x130

The End of Interrupt Command Register is used by the interrupt routine to indicate that the interrupt treatment is complete.

Any value can be written because it is only necessary to make a write to this register location to signal the end of interrupt

treatment.

AIC Spurious Vector Register

Access Type: Read/Write

Reset Value:0

Offset: 0x134

• SPUVEC: Spurious Interrupt Vector Handler Address

The user may store the address of the spurious interrupt handler in this register.

31 30 29 28 27 26 25 24

––––––––

23 22 21 20 19 18 17 16

––––––––

15 14 13 12 11 10 9 8

––––––––

76543210

––––––––

31 30 29 28 27 26 25 24

SPUVEC

23 22 21 20 19 18 17 16

SPUVEC

15 14 13 12 11 10 9 8

SPUVEC

76543210

SPUVEC

AT91X40 Series

1354D–ATARM–08/02

Standard Interrupt

Sequence

It is assumed that:

• The Advanced Interrupt Controller has been programmed, AIC_SVR are loaded

with corresponding interrupt service routine addresses and interrupts are enabled.

• The Instruction at address 0x18(IRQ exception vector address) is

ldr pc, [pc, # - &F20]

When NIRQ is asserted, if the bit I of CPSR is 0, the sequence is:

1. The CPSR is stored in SPSR_irq, the current value of the Program Counter is

loaded in the IRQ link register (r14_irq) and the Program Counter (r15) is loaded

with 0x18. In the following cycle during fetch at address 0x1C, the ARM core

adjusts r14_irq, decrementing it by 4.

2. The ARM core enters IRQ Mode, if it is not already.

3. When the instruction loaded at address 0x18 is executed, the Program Counter

is loaded with the value read in AIC_IVR. Reading the AIC_IVR has the following

effects:

– Set the current interrupt to be the pending one with the highest priority. The

current level is the priority level of the current interrupt.

– De-assert the NIRQ line on the processor. (Even if vectoring is not used,

AIC_IVR must be read in order to de-assert NIRQ)

– Automatically clear the interrupt, if it has been programmed to be edge

triggered

– Push the current level on to the stack

– Return the value written in the AIC_SVR corresponding to the current

interrupt

4. The previous step has effect to branch to the corresponding interrupt service

routine. This should start by saving the Link Register(r14_irq) and the

SPSR(SPSR_irq). Note that the Link Register must be decremented by 4 when it

is saved, if it is to be restored directly into the Program Counter at the end of the

interrupt.

5. Further interrupts can then be unmasked by clearing the I bit in the CPSR, allow-

ing re-assertion of the NIRQ to be taken into account by the core. This can occur

if an interrupt with a higher priority than the current one occurs.

6. The Interrupt Handler can then proceed as required, saving the registers which

will be used and restoring them at the end. During this phase, an interrupt of pri-

ority higher than the current level will restart the sequence from step 1. Note that

if the interrupt is programmed to be level sensitive, the source of the interrupt

must be cleared during this phase.

7. The I bit in the CPSR must be set in order to mask interrupts before exiting, to

ensure that the interrupt is completed in an orderly manner.

8. The End Of Interrupt Command Register (AIC_EOICR) must be written in order

to indicate to the AIC that the current interrupt is finished. This causes the cur-

rent level to be popped from the stack, restoring the previous current level if one

exists on the stack. If another interrupt is pending, with lower or equal priority

than old current level but with higher priority than the new current level, the NIRQ

line is re-asserted, but the interrupt sequence does not immediately start

because the I bit is set in the core.

9. The SPSR (SPSR_irq) is restored. Finally, the saved value of the Link Register is

restored directly into the PC. This has effect of returning from the interrupt to

whatever was being executed before, and of loading the CPSR with the stored

72 AT91X40 Series

1354D–ATARM–08/02

SPSR, masking or unmasking the interrupts depending on the state saved in the

SPSR (the previous state of the ARM core).

Note: The I bit in the SPSR is significant. If it is set, it indicates that the ARM core was just

about to mask IRQ interrupts when the mask instruction was interrupted. Hence, when

the SPSR is restored, the mask instruction is completed (IRQ is masked).

AT91X40 Series

1354D–ATARM–08/02

Fast Interrupt Sequence

It is assumed that:

• The Advanced Interrupt Controller has been programmed, AIC_SVR[0] is loaded

with fast interrupt service routine address and the fast interrupt is enabled.

• The Instruction at address 0x1C(FIQ exception vector address) is:

• ldr pc, [pc, # - &F20].

• Nested Fast Interrupts are not needed by the user.

When NFIQ is asserted, if the bit F of CPSR is 0, the sequence is:

1. The CPSR is stored in SPSR_fiq, the current value of the Program Counter is

loaded in the FIQ link register (r14_fiq) and the Program Counter (r15) is loaded

with 0x1C. In the following cycle, during fetch at address 0x20, the ARM core

adjusts r14_fiq, decrementing it by 4.

2. The ARM core enters FIQ Mode.

3. When the instruction loaded at address 0x1C is executed, the Program Counter

is loaded with the value read in AIC_FVR. Reading the AIC_FVR has effect of

automatically clearing the fast interrupt (source 0 connected to the FIQ line), if it

has been programmed to be edge triggered. In this case only, it de-asserts the

NFIQ line on the processor.

4. The previous step has effect to branch to the corresponding interrupt service

routine. It is not necessary to save the Link Register(r14_fiq) and the

SPSR(SPSR_fiq) if nested fast interrupts are not needed.

5. The Interrupt Handler can then proceed as required. It is not necessary to save

registers r8 to r13 because FIQ Mode has its own dedicated registers and the

user r8 to r13 are banked. The other registers, r0 to r7, must be saved before

being used, and restored at the end (before the next step). Note that if the fast

interrupt is programmed to be level sensitive, the source of the interrupt must be

cleared during this phase in order to de-assert the NFIQ line.

6. Finally, the Link Register (r14_fiq) is restored into the PC after decrementing it by

4 (with instruction sub pc, lr, #4 for example). This has effect of returning from the

interrupt to whatever was being executed before, and of loading the CPSR with

the SPSR, masking or unmasking the fast interrupt depending on the state saved

in the SPSR.

Note: The F bit in the SPSR is significant. If it is set, it indicates that the ARM core was just

about to mask FIQ interrupts when the mask instruction was interrupted. Hence when

the SPSR is restored, the interrupted instruction is completed (FIQ is masked).

74 AT91X40 Series

1354D–ATARM–08/02

PIO: Parallel I/O

Controller

The AT91X40 Series has 32 programmable I/O lines. Six pins are dedicated as general

purpose I/O pins (P16, P17, P18, P19, P23 and P24). Other I/O lines are multiplexed

with an external signal of a peripheral to optimize the use of available package pins (see

Table 10). The PIO controller also provides an internal interrupt signal to the Advanced

Interrupt Controller.

Multiplexed I/O Lines Some I/O lines are multiplexed with an I/O signal of a peripheral. After reset, the pin is

generally controlled by the PIO Controller and is in Input Mode. Table 10 indicates which

of these pins are not controlled by the PIO Controller after reset.

When a peripheral signal is not used in an application, the corresponding pin can be

used as a parallel I/O. Each parallel I/O line is bi-directional, whether the peripheral

defines the signal as input or output. Figure 34 shows the multiplexing of the peripheral

signals with Parallel I/O signals.

If a pin is multiplexed between the PIO Controller and a peripheral, the pin is controlled

by the registers PIO_PER (PIO Enable) and PIO_PDR (PIO Disable). The register

PIO_PSR (PIO Status) indicates whether the pin is controlled by the corresponding

peripheral or by the PIO Controller.

If a pin is a general-purpose parallel I/O pin (not multiplexed with a peripheral),

PIO_PER and PIO_PDR have no effect and PIO_PSR returns 1 for the bits correspond-

ing to these pins.

When the PIO is selected, the peripheral input line is connected to zero.

Output Selection The user can enable each individual I/O signal as an output with the registers PIO_OER

(Output Enable) and PIO_ODR (Output Disable). The output status of the I/O signals

can be read in the register PIO_OSR (Output Status). The direction defined has effect

only if the pin is configured to be controlled by the PIO Controller.

I/O Levels Each pin can be configured to be driven high or low. The level is defined in four different

ways, according to the following conditions.

If a pin is controlled by the PIO Controller and is defined as an output (see “Output

Selection” above), the level is programmed using the registers PIO_SODR (Set Output

Data) and PIO_CODR (Clear Output Data). In this case, the programmed value can be

read in PIO_ODSR (Output Data Status).

If a pin is controlled by the PIO Controller and is not defined as an output, the level is

determined by the external circuit.

If a pin is not controlled by the PIO Controller, the state of the pin is defined by the

peripheral (see peripheral datasheets).

In all cases, the level on the pin can be read in the register PIO_PDSR (Pin Data

Status).

Filters Optional input glitch filtering is available on each pin of the AT91M40800, the

AT91M40807 and the AT91R40807. Filtering is controlled by the registers PIO_IFER

(Input Filter Enable) and PIO_IFDR (Input Filter Disable). The input glitch filtering can be

selected whether the pin is used for its peripheral function or as a parallel I/O line. The

each pin.

AT91X40 Series

1354D–ATARM–08/02

Interrupts Each parallel I/O can be programmed to generate an interrupt when a level change

occurs. This is controlled by the PIO_IER (Interrupt Enable) and PIO_IDR (Interrupt Dis-

able) registers which enable/disable the I/O interrupt by setting/clearing the

corresponding bit in the PIO_IMR. When a change in level occurs, the corresponding bit

in the PIO_ISR (Interrupt Status) is set whether the pin is used as a PIO or a peripheral

and whether it is defined as input or output. If the corresponding interrupt in PIO_IMR

(Interrupt Mask) is enabled, the PIO interrupt is asserted.

When PIO_ISR is read, the register is automatically cleared.

User Interface Each individual I/O is associated with a bit position in the Parallel I/O user interface reg-

isters. Each of these registers are 32 bits wide. If a parallel I/O line is not defined, writing

to the corresponding bits has no effect. Undefined bits read zero.

76 AT91X40 Series

1354D–ATARM–08/02

Figure 34. Parallel I/O Multiplexed with a Bi-directional Signal

Note: The filter is not implemented in the AT91R40008.

Pad

PIO_OSR

PIO_PSR

PIO_ODSR

Filter*

PIO_IFSR

PIO_PSR

Event

Detection

PIO_PDSR

PIO_ISR

PIO_IMR

Peripheral

Output

Enable

Peripheral

Output

Peripheral

Input

PIOIRQ

Pad Output Enable

Pad Output

Pad Input

AT91X40 Series

1354D–ATARM–08/02

Note: Bit Number refers to the data bit that corresponds to this signal in each of the User Interface registers.

Table 10. Multiplexed Parallel I/Os

PIO Controller Peripheral

Reset State

Number

Bit

Number(1) Port Name Port Name Signal Description Signal Direction

0 P0 TCLK0 Timer 0 Clock signal Input PIO Input 49

1 P1 TIOA0 Timer 0 Signal A Bi-directional PIO Input 50

2 P2 TIOB0 Timer 0 Signal B Bi-directional PIO Input 51

3 P3 TCLK1 Timer 1 Clock signal Input PIO Input 54

4 P4 TIOA1 Timer 1 Signal A Bi-directional PIO Input 55

5 P5 TIOB1 Timer 1 Signal B Bi-directional PIO Input 56

6 P6 TCLK2 Timer 2 Clock signal Input PIO Input 57

7 P7 TIOA2 Timer 2 Signal A Bi-directional PIO Input 58

8 P8 TIOB2 Timer 2 Signal B Bi-directional PIO Input 59

9 P9 IRQ0 External Interrupt 0 Input PIO Input 60

10 P10 IRQ1 External Interrupt 1 Input PIO Input 63

11 P11 IRQ2 External Interrupt 2 Input PIO Input 64

12 P12 FIQ Fast Interrupt Input PIO Input 66

13 P13 SCK0 USART 0 clock signal Bi-directional PIO Input 67

14 P14 TXD0 USART 0 transmit data signal Output PIO Input 68

15 P15 RXD0 USART 0 receive data signal Input PIO Input 69

16 P16 – – – PIO Input 70

17 P17 – – – PIO Input 71

18 P18 – – – PIO Input 72

19 P19 – – – PIO Input 73

20 P20 SCK1 USART 1 clock signal Bi-directional PIO Input 74

21 P21 TXD1 USART 1 transmit data signal Output PIO Input 75

22 P22 RXD1 USART 1 receive data signal Input PIO Input 76

23 P23 – – – PIO Input 83

24 P24 – – – PIO Input 84

25 P25 MCKO Master Clock Output Output MCKO 85

26 P26 NCS2 Chip Select 2 Output NCS2 99

27 P27 NCS3 Chip Select 3 Output NCS3 100

28 P28 A20/CS7 Address 20/Chip Select 7 Output A20 25

29 P29 A21/CS6 Address 21/Chip Select 6 Output A21 26

30 P30 A22/CS5 Address 22/Chip Select 5 Output A22 29

31 P31 A23/CS4 Address 23/Chip Select 4 Output A23 30

78 AT91X40 Series

1354D–ATARM–08/02

PIO User Interface

PIO Base Address: 0xFFFF0000 (Code Label PIO_BASE)

Notes: 1. The reset value of this register depends on the level of the external pins at reset.

2. This register is cleared at reset. However, the first read of the register can give a value not equal to zero if any changes have

occurred on any pins between the reset and the read.

3. This register exists in the AT91R40008 but its value has no meaning, since the filters are not implemented.

Table 11. PIO Controller Memory Map

Offset Register Name Access Reset State

0x00 PIO Enable Register PIO_PER Write Only –

0x04 PIO Disable Register PIO_PDR Write Only –

0x08 PIO Status Register PIO_PSR Read Only 0x01FFFFFF

(see also Table

10)

0x0C Reserved – – –

0x10 Output Enable Register PIO_OER Write Only –

0x14 Output Disable Register PIO_ODR Write Only –

0x18 Output Status Register PIO_OSR Read Only 0

0x1C Reserved – – –

0x20 Input Filter Enable Register PIO_IFER Write Only –

0x24 Input Filter Disable Register PIO_IFDR Write Only –

0x28 Input Filter Status Register(3) PIO_IFSR Read Only 0

0x2C Reserved – – –

0x30 Set Output Data Register PIO_SODR Write Only –

0x34 Clear Output Data Register PIO_CODR Write Only –

0x38 Output Data Status Register PIO_ODSR Read Only 0

0x3C Pin Data Status Register PIO_PDSR Read Only (see Note 1)

0x40 Interrupt Enable Register PIO_IER Write Only –

0x44 Interrupt Disable Register PIO_IDR Write Only –

0x48 Interrupt Mask Register PIO_IMR Read Only 0

0x4C Interrupt Status Register PIO_ISR Read Only (see Note 2)

AT91X40 Series

1354D–ATARM–08/02

PIO Enable Register

Access Type:Write Only

Offset: 0x00

This register is used to enable individual pins to be controlled by the PIO Controller instead of the associated peripheral.

When the PIO is enabled, the associated peripheral input (if any) is held at logic zero.

1 = Enables the PIO to control the corresponding pin (disables peripheral control of the pin).

0 = No effect.

PIO Disable Register

Access Type:Write Only

Offset: 0x04

This register is used to disable PIO control of individual pins. When the PIO control is disabled, the normal peripheral func-

tion is enabled on the corresponding pin.

1 = Disables PIO control (enables peripheral control) on the corresponding pin.

0 = No effect.

31 30 29 28 27 26 25 24

P31 P30 P29 P28 P27 P26 P25 P24

23 22 21 20 19 18 17 16

P23 P22 P21 P20 P19 P18 P17 P16

15 14 13 12 11 10 9 8

P15 P14 P13 P12 P11 P10 P9 P8

76543210

P7 P6 P5 P4 P3 P2 P1 P0

31 30 29 28 27 26 25 24

P31 P30 P29 P28 P27 P26 P25 P24

23 22 21 20 19 18 17 16

P23 P22 P21 P20 P19 P18 P17 P16

15 14 13 12 11 10 9 8

P15 P14 P13 P12 P11 P10 P9 P8

76543210

P7 P6 P5 P4 P3 P2 P1 P0

80 AT91X40 Series

1354D–ATARM–08/02

PIO Status Register

Access Type: Read Only

Reset Value: 0x01FFFFFF

Offset: 0x08

This register indicates which pins are enabled for PIO control. This register is updated when PIO lines are enabled or

disabled.

1 = PIO is active on the corresponding line (peripheral is inactive).

0 = PIO is inactive on the corresponding line (peripheral is active).

31 30 29 28 27 26 25 24

P31 P30 P29 P28 P27 P26 P25 P24

23 22 21 20 19 18 17 16

P23 P22 P21 P20 P19 P18 P17 P16

15 14 13 12 11 10 9 8

P15 P14 P13 P12 P11 P10 P9 P8

76543210

P7 P6 P5 P4 P3 P2 P1 P0

AT91X40 Series

1354D–ATARM–08/02

PIO Output Enable Register

Access Type:Write Only

Offset: 0x10

This register is used to enable PIO output drivers. If the pin is driven by a peripheral, this has no effect on the pin, but the

information is stored. The register is programmed as follows:

1 = Enables the PIO output on the corresponding pin.

0 = No effect.

PIO Output Disable Register

Access Type:Write Only

Offset: 0x14

This register is used to disable PIO output drivers. If the pin is driven by the peripheral, this has no effect on the pin, but the

information is stored. The register is programmed as follows:

1 = Disables the PIO output on the corresponding pin.

0 = No effect.

31 30 29 28 27 26 25 24

P31 P30 P29 P28 P27 P26 P25 P24

23 22 21 20 19 18 17 16

P23 P22 P21 P20 P19 P18 P17 P16

15 14 13 12 11 10 9 8

P15 P14 P13 P12 P11 P10 P9 P8

76543210

P7 P6 P5 P4 P3 P2 P1 P0

31 30 29 28 27 26 25 24

P31 P30 P29 P28 P27 P26 P25 P24

23 22 21 20 19 18 17 16

P23 P22 P21 P20 P19 P18 P17 P16

15 14 13 12 11 10 9 8

P15 P14 P13 P12 P11 P10 P9 P8

76543210

P7 P6 P5 P4 P3 P2 P1 P0

82 AT91X40 Series

1354D–ATARM–08/02

PIO Output Status Register

Access Type: Read Only

Reset Value:0

Offset:0x18

This register shows the PIO pin control (output enable) status which is programmed in PIO_OER and PIO ODR. The

defined value is effective only if the pin is controlled by the PIO. The register reads as follows:

1 = The corresponding PIO is output on this line.

0 = The corresponding PIO is input on this line.

31 30 29 28 27 26 25 24

P31 P30 P29 P28 P27 P26 P25 P24

23 22 21 20 19 18 17 16

P23 P22 P21 P20 P19 P18 P17 P16

15 14 13 12 11 10 9 8

P15 P14 P13 P12 P11 P10 P9 P8

76543210

P7 P6 P5 P4 P3 P2 P1 P0

AT91X40 Series

1354D–ATARM–08/02

PIO Input Filter Enable Register

Access Type:Write Only

Offset: 0x20

This register is used to enable input glitch filters. It affects the pin whether or not the PIO is enabled. The register is pro-

grammed as follows:

1 = Enables the glitch filter on the corresponding pin.

0 = No effect.

PIO Input Filter Disable Register

Access Type:Write Only

Offset: 0x24

This register is used to disable input glitch filters. It affects the pin whether or not the PIO is enabled. The register is pro-

grammed as follows:

1 = Disables the glitch filter on the corresponding pin.

0 = No effect.

31 30 29 28 27 26 25 24

P31 P30 P29 P28 P27 P26 P25 P24

23 22 21 20 19 18 17 16

P23 P22 P21 P20 P19 P18 P17 P16

15 14 13 12 11 10 9 8

P15 P14 P13 P12 P11 P10 P9 P8

76543210

P7 P6 P5 P4 P3 P2 P1 P0

31 30 29 28 27 26 25 24

P31 P30 P29 P28 P27 P26 P25 P24

23 22 21 20 19 18 17 16

P23 P22 P21 P20 P19 P18 P17 P16

15 14 13 12 11 10 9 8

P15 P14 P13 P12 P11 P10 P9 P8

76543210

P7 P6 P5 P4 P3 P2 P1 P0

84 AT91X40 Series

1354D–ATARM–08/02

PIO Input Filter Status Register

Access Type: Read Only

Reset Value:0

Offset: 0x28

This register indicates which pins have glitch filters selected. It is updated when PIO outputs are enabled or disabled by

writing to PIO_IFER or PIO_IFDR.

1 = Filter is selected on the corresponding input (peripheral and PIO).

0 = Filter is not selected on the corresponding input.

31 30 29 28 27 26 25 24

P31 P30 P29 P28 P27 P26 P25 P24

23 22 21 20 19 18 17 16

P23 P22 P21 P20 P19 P18 P17 P16

15 14 13 12 11 10 9 8

P15 P14 P13 P12 P11 P10 P9 P8

76543210

P7 P6 P5 P4 P3 P2 P1 P0

AT91X40 Series

1354D–ATARM–08/02

PIO Set Output Data Register

Access Type:Write Only

Offset: 0x30

This register is used to set PIO output data. It affects the pin only if the corresponding PIO output line is enabled and if the

pin is controlled by the PIO. Otherwise, the information is stored.

1 = PIO output data on the corresponding pin is set.

0 = No effect.

PIO Clear Output Data Register

Access Type:Write Only

Offset: 0x34

This register is used to clear PIO output data. It affects the pin only if the corresponding PIO output line is enabled and if the

pin is controlled by the PIO. Otherwise, the information is stored.

1 = PIO output data on the corresponding pin is cleared.

0 = No effect.

31 30 29 28 27 26 25 24

P31 P30 P29 P28 P27 P26 P25 P24

23 22 21 20 19 18 17 16

P23 P22 P21 P20 P19 P18 P17 P16

15 14 13 12 11 10 9 8

P15 P14 P13 P12 P11 P10 P9 P8

76543210

P7 P6 P5 P4 P3 P2 P1 P0

31 30 29 28 27 26 25 24

P31 P30 P29 P28 P27 P26 P25 P24

23 22 21 20 19 18 17 16

P23 P22 P21 P20 P19 P18 P17 P16

15 14 13 12 11 10 9 8

P15 P14 P13 P12 P11 P10 P9 P8

76543210

P7 P6 P5 P4 P3 P2 P1 P0

86 AT91X40 Series

1354D–ATARM–08/02

PIO Output Data Status Register

Access Type: Read Only

Reset Value:0

Offset: 0x38

This register shows the output data status which is programmed in PIO_SODR or PIO_CODR. The defined value is effec-

tive only if the pin is controlled by the PIO Controller and only if the pin is defined as an output.

1 = The output data for the corresponding line is programmed to 1.

0 = The output data for the corresponding line is programmed to 0.

PIO Pin Data Status Register

Access Type: Read Only

Reset Value: see Table 11

Offset:0x3C

This register shows the state of the physical pin of the chip. The pin values are always valid regardless of whether the pins

are enabled as PIO, peripheral, input or output. The register reads as follows:

1 = The corresponding pin is at logic 1.

0 = The corresponding pin is at logic 0.

31 30 29 28 27 26 25 24

P31 P30 P29 P28 P27 P26 P25 P24

23 22 21 20 19 18 17 16

P23 P22 P21 P20 P19 P18 P17 P16

15 14 13 12 11 10 9 8

P15 P14 P13 P12 P11 P10 P9 P8

76543210

P7 P6 P5 P4 P3 P2 P1 P0

31 30 29 28 27 26 25 24

P31 P30 P29 P28 P27 P26 P25 P24

23 22 21 20 19 18 17 16

P23 P22 P21 P20 P19 P18 P17 P16

15 14 13 12 11 10 9 8

P15 P14 P13 P12 P11 P10 P9 P8

76543210

P7 P6 P5 P4 P3 P2 P1 P0

AT91X40 Series

1354D–ATARM–08/02

PIO Interrupt Enable Register

Access Type:Write Only

Offset: 0x40

This register is used to enable PIO interrupts on the corresponding pin. It has effect whether PIO is enabled or not.

1 = Enables an interrupt when a change of logic level is detected on the corresponding pin.

0 = No effect.

PIO Interrupt Disable Register

Access Type:Write Only

Offset: 0x44

This register is used to disable PIO interrupts on the corresponding pin. It has effect whether the PIO is enabled or not.

1 = Disables the interrupt on the corresponding pin. Logic level changes are still detected.

0 = No effect.

31 30 29 28 27 26 25 24

P31 P30 P29 P28 P27 P26 P25 P24

23 22 21 20 19 18 17 16

P23 P22 P21 P20 P19 P18 P17 P16

15 14 13 12 11 10 9 8

P15 P14 P13 P12 P11 P10 P9 P8

76543210

P7 P6 P5 P4 P3 P2 P1 P0

31 30 29 28 27 26 25 24

P31 P30 P29 P28 P27 P26 P25 P24

23 22 21 20 19 18 17 16

P23 P22 P21 P20 P19 P18 P17 P16

15 14 13 12 11 10 9 8

P15 P14 P13 P12 P11 P10 P9 P8

76543210

P7 P6 P5 P4 P3 P2 P1 P0

88 AT91X40 Series

1354D–ATARM–08/02

PIO Interrupt Mask Register

Access Type: Read Only

Reset Value:0

Offset: 0x48

This register shows which pins have interrupts enabled. It is updated when interrupts are enabled or disabled by writing to

PIO_IER or PIO_IDR.

1 = Interrupt is enabled on the corresponding input pin.

0 = Interrupt is not enabled on the corresponding input pin.

PIO Interrupt Status Register

Access Type: Read Only

Reset Value:0

Offset:0x4C

This register indicates for each pin when a logic value change has been detected (rising or falling edge). This is valid

whether the PIO is selected for the pin or not and whether the pin is an input or output.

The register is reset to zero following a read, and at reset.

1 = At least one change has been detected on the corresponding pin since the register was last read.

0 = No change has been detected on the corresponding pin since the register was last read.

31 30 29 28 27 26 25 24

P31 P30 P29 P28 P27 P26 P25 P24

23 22 21 20 19 18 17 16

P23 P22 P21 P20 P19 P18 P17 P16

15 14 13 12 11 10 9 8

P15 P14 P13 P12 P11 P10 P9 P8

76543210

P7 P6 P5 P4 P3 P2 P1 P0

31 30 29 28 27 26 25 24

P31 P30 P29 P28 P27 P26 P25 P24

23 22 21 20 19 18 17 16

P23 P22 P21 P20 P19 P18 P17 P16

15 14 13 12 11 10 9 8

P15 P14 P13 P12 P11 P10 P9 P8

76543210

P7 P6 P5 P4 P3 P2 P1 P0

AT91X40 Series

1354D–ATARM–08/02

WD: Watchdog Timer The AT91X40 Series has an internal watchdog timer which can be used to prevent sys-

tem lock-up if the software becomes trapped in a deadlock. In normal operation the user

reloads the watchdog at regular intervals before the timer overflow occurs. If an overflow

does occur, the watchdog timer generates one or a combination of the following signals,

depending on the parameters in WD_OMR (Overflow Mode Register):

• If RSTEN is set, an internal reset is generated (WD_RESET as shown in Figure 35).

• If IRQEN is set, a pulse is generated on the signal WDIRQ which is connected to the

Advanced Interrupt Controller

• If EXTEN is set, a low level is driven on the NWDOVF signal for a duration of 8 MCK

cycles.

The watchdog timer has a 16-bit down counter. Bits 12-15 of the value loaded when the

watchdog is restarted are programmable using the HPVC parameter in WD_CMR

(Clock Mode). Four clock sources are available to the watchdog counter: MCK/8,

MCK/32, MCK/128 or MCK/1024. The selection is made using the WDCLKS parameter

in WD_CMR. This provides a programmable time-out period of 1 ms to 2 sec. with a 33

MHz system clock.

All write accesses are protected by control access keys to help prevent corruption of the

watchdog should an error condition occur. To update the contents of the mode and con-

trol registers it is necessary to write the correct bit pattern to the control access key bits

at the same time as the control bits are written (the same write access).

Figure 35. Watchdog Timer Block Diagram

Advanced

Peripheral

Bus (APB)

WD_RESET

WDIRQ

MCKI/8

MCKI/32

MCKI/128

MCKI/1024

Control Logic

Clock Select

16-bit

Programmable

Down Counter

CLK_CNT

Clear

Overflow

NWDOVF

90 AT91X40 Series

1354D–ATARM–08/02

WD User Interface

WD Base Address: 0xFFFF8000 (Code Label WD_BASE)

WD Overflow Mode Register

Name:WD_OMR

Access: Read/Write

Reset Value:0

Offset: 0x00

• WDEN: Watch Dog Enable (Code Label WD_WDEN)

0 = Watch Dog is disabled and does not generate any signals.

1 = Watch Dog is enabled and generates enabled signals.

• RSTEN: Reset Enable (Code Label WD_RSTEN)

0 = Generation of an internal reset by the Watch Dog is disabled.

1 = When overflow occurs, the Watch Dog generates an internal reset.

• IRQEN: Interrupt Enable (Code Label WD_IRQEN)

0 = Generation of an interrupt by the Watch Dog is disabled.

1 = When overflow occurs, the Watch Dog generates an interrupt.

• EXTEN: External Signal Enable (Code Label WD_EXTEN)

0 = Generation of a pulse on the pin NWDOVF by the Watch Dog is disabled.

1 = When an overflow occurs, a pulse on the pin NWDOVF is generated.

• OKEY: Overflow Access Key (Code Label WD_OKEY)

Used only when writing WD_OMR. OKEY is read as 0.

0x234 = Write access in WD_OMR is allowed.

Other value = Write access in WD_OMR is prohibited.

Table 12. WD Memory Map

Offset Register Name Access Reset State

0x00 Overflow Mode Register WD_OMR Read/Write 0

0x04 Clock Mode Register WD_CMR Read/Write 0

0x08 Control Register WD_CR Write Only –

0x0C Status Register WD_SR Read Only 0

31 30 29 28 27 26 25 24

––––––––

23 22 21 20 19 18 17 16

––––––––

15 14 13 12 11 10 9 8

OKEY

76543210

OKEY EXTEN IRQEN RSTEN WDEN

AT91X40 Series

1354D–ATARM–08/02

WD Clock Mode Register

Name:WD_CMR

Access: Read/Write

Reset Value:0

Offset: 0x04

• WDCLKS: Clock Selection

• HPCV: High Preload Counter Value (Code Label WD_HPCV)

Counter is preloaded when watchdog counter is restarted with bits 0 to 11 set (FFF) and bits 12 to 15 equaling HPCV.

• CKEY: Clock Access Key (Code Label WD_CKEY)

Used only when writing WD_CMR. CKEY is read as 0.

0x06E: Write access in WD_CMR is allowed.

Other value: Write access in WD_CMR is prohibited.

31 30 29 28 27 26 25 24

––––––––

23 22 21 20 19 18 17 16

––––––––

15 14 13 12 11 10 9 8

CKEY

76543210

CKEY –HPCV WDCLKS

WDCLKS Clock Selected

Code Label

WD_WDCLKS

00MCK/8 WD_WDCLKS_MCK8

01MCK/32 WD_WDCLKS_MCK32

10MCK/128 WD_WDCLKS_MCK128

1 1 MCK/1024 WD_WDCLKS_MCK1024

92 AT91X40 Series

1354D–ATARM–08/02

WD Control Register

Name:WD_CR

Access:Write Only

Offset:0x08

• RSTKEY: Restart Key (Code Label WD_RSTKEY)

0xC071 = Watch Dog counter is restarted.

Other value = No effect.

WD Status Register

Name:WD_SR

Access: Read Only

Reset Value:0

Offset:0x0C

• WDOVF: Watchdog Overflow (Code Label WD_WDOVF)

0 = No watchdog overflow.

1 = A watchdog overflow has occurred since the last restart of the watchdog counter or since internal or external reset.

31 30 29 28 27 26 25 24

––––––––

23 22 21 20 19 18 17 16

––––––––

15 14 13 12 11 10 9 8

RSTKEY

76543210

RSTKEY

31 30 29 28 27 26 25 24

––––––––

23 22 21 20 19 18 17 16

––––––––

15 14 13 12 11 10 9 8

––––––––

76543210

–––––––

WDOVF

AT91X40 Series

1354D–ATARM–08/02

WD Enabling Sequence To enable the Watchdog Timer the sequence is as follows:

1. Disable the Watchdog by clearing the bit WDEN:

Write 0x2340 to WD_OMR

This step is unnecessary if the WD is already disabled (reset state).

2. Initialize the WD Clock Mode Register:

Write 0x373C to WD_CMR

(HPCV = 15 and WDCLKS = MCK/8)

3. Restart the timer:

Write 0xC071 to WD_CR

4. Enable the watchdog:

Write 0x2345 to WD_OMR (interrupt enabled)

94 AT91X40 Series

1354D–ATARM–08/02

SF: Special Function

Registers

The AT91X40 Series

rovides re

isters which im

lement the followin

ecial functions.

• Chip identification

• RESET status

• Protect Mode (see “Protect Mode” on page 60)

Chip Identification

Table 13 provides the Chip ID values for the products described in this datasheet.

SF User Interface

Chip ID Base Address = 0xFFF00000 (Code Label SF_BASE)

Table 13. Chip ID Values

Product Chip

AT91M40800 0x14080044

AT91R40807 0x44080746

AT91M40807 0x14080745

AT91R40008 0x44000840

Table 14. SF Memory Map

Offset Register Name Access Reset State

0x00 Chip ID Register SF_CIDR Read Only Hardwired

0x04 Chip ID Extension Register SF_EXID Read Only Hardwired

0x08 Reset Status Register SF_RSR Read Only See register

description

0x0C Memory Mode Register SF_MMR Read/Write 0x0

0x10 Reserved – – –

0x14 Reserved – – –

0x18 Protect Mode Register SF_PMR Read/Write 0x0

AT91X40 Series

1354D–ATARM–08/02

Chip ID Register

Access Type: Read Only

Reset Value: Hardwired

Offset: 0x00

• VERSION: Version of the chip (Code Label SF_VERSION)

This value is incremented by one with each new version of the chip (from zero to a maximum value of 31).

• NVPSIZ: Non Volatile Program Memory Size

• NVDSIZ: Non Volatile Data Memory Size

31 30 29 28 27 26 25 24

EXT NVPTYP ARCH

23 22 21 20 19 18 17 16

ARCH VDSIZ

15 14 13 12 11 10 9 8

NVDSIZ NVPSIZ

76543210

010 VERSION

NVPSIZ Size

Code Label

SF_NVPSIZ

0000None SF_NVPSIZ_NONE

001132K bytes SF_NVPSIZ_32K

010164K bytes SF_NVPSIZ_64K

0111128K bytes SF_NVPSIZ_128K

1001256K bytes SF_NVPSIZ_256K

Others Reserved –

NVDSIZ Size

Code Label

SF_NVDSIZ

0000None SF_NVDSIZ_NONE

Others Reserved –

96 AT91X40 Series

1354D–ATARM–08/02

• VDSIZ: Volatile Data Memory Size

• ARCH: Chip Architecture (Code Label SF_ARCH)

Code of Architecture: Two BCD digits.

• NVPTYP: Non Volatile Program Memory Type

• EXT: Extension Flag (Code Label SF_EXT)

0 = Chip ID has a single register definition without extensions

1 = An extended Chip ID exists (to be defined in the future).

Chip ID Extension Register

Access Type: Read Only

Reset Value: Hardwired

Offset:0x04

This register is reserved for future use. It will be defined when needed.

VDSIZ Size

Code Label

SF_VDSIZ

0000None SF_VDSIZ_NONE

00011K bytes SF_VDSIZ_1K

00102K bytes SF_VDSIZ_2K

01004K bytes SF_VDSIZ_4K

10008K bytes SF_VDSIZ_8K

Others Reserved –

0100 0000 AT91x40yyy

Code Label

SF_ARCH_AT91x40

NVPTYP Type

Code Label

SF_NVPTYP

0 0 0 Reserved –

001“F” Series SF_NVPTYP_M

1 x x Reserved –

100“R” Series SF_NVPTYP_R

AT91X40 Series

1354D–ATARM–08/02

Reset Status Register

Access Type: Read Only

Reset Value:See Below

Offset:0x08

• RESET: Reset Status Information

This field indicates whether the reset was demanded by the external system (via NRST) or by the Watchdog internal reset

request.

31 30 29 28 27 26 25 24

––––––––

23 22 21 20 19 18 17 16

––––––––

15 14 13 12 11 10 9 8

––––––––

76543210

RESET

Reset Cause of Reset

Code Label

SF_RESET

0x6C External Pin SF_EXT_RESET

0x53 Internal Watchdog SF_WD_RESET

98 AT91X40 Series

1354D–ATARM–08/02

SF Memory Mode Register

This register only applies to the AT91R40807.

Access Type: Read/Write

Reset Value:0

Offset:0x0C

• RAMWU: Internal Extended RAM Write Detection (Code Label SF_RAMWU)

0 = Writing in RAM generates an Abort.

1 = Writing in RAM is allowed.

SF Protect Mode Register

Access Type: Read/Write

Reset Value:0

Offset:0x18

• PMRKEY: Protect Mode Register Key (Code Label SF_PMRKEY)

Used only when writing SF_PMR. PMRKEY is reads 0.

0x27A8: Write access in SF_PMR is allowed.

Other value: Write access in SF_PMR is prohibited.

• AIC: AIC Protect Mode Enable (Code Label SF_AIC)

0 = The Advanced Interrupt Controller runs in Normal Mode.

1 = The Advanced Interrupt Controller runs in Protect Mode.

See “Protect Mode” on page 60.

31 30 29 28 27 26 25 24

––––––––

23 22 21 20 19 18 17 16

––––––––

15 14 13 12 11 10 9 8

––––––––

76543210

–––––––

RAMWU

31 30 29 28 27 26 25 24

PMRKEY

23 22 21 20 19 18 17 16

PMRKEY

15 14 13 12 11 10 9 8

––––––––

76543210

––

AIC –––––

AT91X40 Series

1354D–ATARM–08/02

USART: Universal

Synchronous/

Asynchronous

Receiver/

Transmitter

The AT91X40 Series provides two identical, full-duplex, universal synchronous/asyn-

chronous receiver/transmitters that interface to the APB and are connected to the

Peripheral Data Controller.

The main features are:

• Programmable Baud Rate Generator

• Parity, Framing and Overrun Error Detection

• Line Break Generation and Detection

• Automatic Echo, Local Loopback and Remote Loopback channel modes

• Multi-drop Mode: Address Detection and Generation

• Interrupt Generation

• Two Dedicated Peripheral Data Controller channels

• 5-, 6-, 7-, 8- and 9-bit character length

Figure 36. USART Block Diagram

Pin Description

Each USART channel has the following external signals:

Notes: 1. After a hardware reset, the USART pins are not enabled by default (see “PIO: Parallel I/O Controller” on page 74). The user

must configure the PIO Controller before enabling the transmitter or receiver.

2. If the user selects one of the internal clocks, SCK can be configured as a PIO.

Peripheral Data Controller

Receiver

Channel

Transmitter

Channel

Control Logic

Interrupt Control

Baud Rate Generator

Receiver

Transmitter

AMBA

ASB

APB

USxIRQ

MCK

MCK/8

RXD

TXD

SCK

USART Channel

Baud Rate Clock

PIO:

Parallel

I/O

Controller

Name Description

SCK

USART Serial clock can be configured as input or output:

SCK is configured as input if an External clock is selected (USCLKS[1] = 1)

SCK is driven as output if the External Clock is disabled (USCLKS[1] = 0) and Clock output is enabled (CLKO = 1)

TXD Transmit Serial Data is an output

RXD Receive Serial Data is an input

100 AT91X40 Series

1354D–ATARM–08/02

Baud Rate Generator The Baud Rate Generator provides the bit period clock (the Baud Rate clock) to both the

Receiver and the Transmitter.

The Baud Rate Generator can select between external and internal clock sources. The

external clock source is SCK. The internal clock sources can be either the master clock

(MCK) or the master clock divided by 8 (MCK/8).

Note: In all cases, if an external clock is used, the duration of each of its levels must be longer

than the system clock (MCK) period. The external clock frequency must be at least 2.5

times lower than the system clock.

When the USART is programmed to operate in Asynchronous Mode (SYNC = 0 in the

Mode Register US_MR), the selected clock is divided by 16 times the value (CD) written

in US_BRGR (Baud Rate Generator Register). If US_BRGR is set to 0, the Baud Rate

Clock is disabled.

When the USART is programmed to operate in Synchronous Mode (SYNC = 1) and the

selected clock is internal (USCLKS[1] = 0 in the Mode Register US_MR), the Baud Rate

Clock is the internal selected clock divided by the value written in US_BRGR. If

US_BRGR is set to 0, the Baud Rate Clock is disabled.

In Synchronous Mode with external clock selected (USCLKS[1] = 1), the clock is pro-

vided directly by the signal on the SCK pin. No division is active. The value written in

US_BRGR has no effect.

Figure 37. Baud Rate Generator

Baud Rate =Selected Clock

16 x CD

Baud Rate =Selected Clock

USCLKS [1]

MCK

MCK/8

SCK

CLK 16-bit Counter

1Baud Rate

Clock

SYNC

USCLKS [1]

OUT

Divide

by 16

SYNC

USCLKS [0]

101

AT91X40 Series

1354D–ATARM–08/02

Receiver

Asynchronous Receiver The USART is configured for asynchronous operation when SYNC = 0 (bit 7 of

US_MR). In Asynchronous Mode, the USART detects the start of a received character

by sampling the RXD signal until it detects a valid start bit. A low level (space) on RXD is

interpreted as a valid start bit if it is detected for more than 7 cycles of the sampling

clock, which is 16 times the baud rate. Hence a space which is longer than 7/16 of the

bit period is detected as a valid start bit. A space which is 7/16 of a bit period or shorter

is ignored and the receiver continues to wait for a valid start bit.

When a valid start bit has been detected, the receiver samples the RXD at the theoreti-

cal mid-point of each bit. It is assumed that each bit lasts 16 cycles of the sampling clock

(one bit period) so the sampling point is 8 cycles (0.5 bit periods) after the start of the bit.

The first sampling point is therefore 24 cycles (1.5 bit periods) after the falling edge of

the start bit was detected. Each subsequent bit is sampled 16 cycles (1 bit period) after

the previous one.

Figure 38. Asynchronous Mode: Start Bit Detection

Figure 39. Asynchronous Mode: Character Reception

16 x Baud

Rate Clock

RXD

True Start

Detection

Sampling

D0 D1 D2 D3 D4 D5 D6 D7

RXD

True Start Detection

Sampling

Parity Bit

Stop Bit

Example: 8-bit, parity enabled 1 stop

1 bit

period

0.5 bit

periods

102 AT91X40 Series

1354D–ATARM–08/02

Synchronous Receiver When configured for synchronous operation (SYNC = 1), the receiver samples the RXD

signal on each rising edge of the Baud Rate clock. If a low level is detected, it is consid-

ered as a start. Data bits, parity bit and stop bit are sampled and the receiver waits for

the next start bit. See example in Figure 40.

Figure 40. Synchronous Mode: Character Reception

Receiver Ready When a complete character is received, it is transferred to the US_RHR and the RXRDY

status bit in US_CSR is set. If US_RHR has not been read since the last transfer, the

OVRE status bit in US_CSR is set.

Parity Error Each time a character is received, the receiver calculates the parity of the received data

bits, in accordance with the field PAR in US_MR. It then compares the result with the

received parity bit. If different, the parity error bit PARE in US_CSR is set.

Framing Error If a character is received with a stop bit at low level and with at least one data bit at high

level, a framing error is generated. This sets FRAME in US_CSR.

Time-out This function allows an idle condition on the RXD line to be detected. The maximum

delay for which the USART should wait for a new character to arrive while the RXD line

is inactive (high level) is programmed in US_RTOR (Receiver Time-out). When this reg-

ister is set to 0, no time-out is detected. Otherwise, the receiver waits for a first character

and then initializes a counter which is decremented at each bit period and reloaded at

each byte reception. When the counter reaches 0, the TIMEOUT bit in US_CSR is set.

The user can restart the wait for a first character with the STTTO (Start Time-out) bit in

US_CR.

Calculation of time-out duration:

D0 D1 D2 D3 D4 D5 D6 D7

RXD

True Start Detection

Sampling

Parity Bit

Stop Bit

Example: 8-bit, parity enabled 1 stop

SCK

Duration =Value x4xBit

eriod

103

AT91X40 Series

1354D–ATARM–08/02

Transmitter The transmitter has the same behavior in both synchronous and asynchronous operat-

ing modes. Start bit, data bits, parity bit and stop bits are serially shifted, lowest

significant bit first, on the falling edge of the serial clock. See example in Figure 41.

The number of data bits is selected in the CHRL field in US_MR.

The parity bit is set according to the PAR field in US_MR.

The number of stop bits is selected in the NBSTOP field in US_MR.

When a character is written to US_THR (Transmit Holding), it is transferred to the Shift

set until a new character is written to US_THR. If Transmit Shift Register and US_THR

are both empty, the TXEMPTY bit in US_CSR is set.

Time-guard The Time-guard function allows the transmitter to insert an idle state on the TXD line

between two characters. The duration of the idle state is programmed in US_TTGR

(Transmitter Time-guard). When this register is set to zero, no time-guard is generated.

Otherwise, the transmitter holds a high level on TXD after each transmitted byte during

the number of bit periods programmed in US_TTGR

Multi-drop Mode When the field PAR in US_MR equals 11X (binary value), the USART is configured to

run in Multi-drop Mode. In this case, the parity error bit PARE in US_CSR is set when

data is detected with a parity bit set to identify an address byte. PARE is cleared with the

Reset Status Bits Command (RSTSTA) in US_CR. If the parity bit is detected low, iden-

tifying a data byte, PARE is not set.

The transmitter sends an address byte (parity bit set) when a Send Address Command

(SENDA) is written to US_CR. In this case, the next byte written to US_THR will be

transmitted as an address. After this any byte transmitted will have the parity bit cleared.

Figure 41. Synchronous and Asynchronous Modes: Character Transmission

Idle state duration

between two characters =Time-

uard

Value xBit

Period

D0 D1 D2 D3 D4 D5 D6 D7

TXD

Start

Bit

Parity

Bit

Stop

Bit

Example: 8-bit, parity enabled 1 stop

Baud Rate

Clock

104 AT91X40 Series

1354D–ATARM–08/02

Break A break condition is a low signal level which has a duration of at least one character

(including start/stop bits and parity).

Transmit Break The transmitter generates a break condition on the TXD line when STTBRK is set in

US_CR (Control Register). In this case, the character present in the Transmit Shift Reg-

ister is completed before the line is held low.

To cancel a break condition on the TXD line, the STPBRK command in US_CR must be

set. The USART completes a minimum break duration of one character length. The TXD

line then returns to high level (idle state) for at least 12 bit periods to ensure that the end

of break is correctly detected. Then the transmitter resumes normal operation.

The BREAK is managed like a character:

• The STTBRK and the STPBRK commands are performed only if the transmitter is

ready (bit TXRDY = 1 in US_CSR)

• The STTBRK command blocks the transmitter holding register (bit TXRDY is

cleared in US_CSR) until the break has started

• A break is started when the Shift Register is empty (any previous character is fully

transmitted). TXEMPTY is cleared in US_CSR. The break blocks the transmitter

shift register until it is completed (high level for at least 12-bit periods after the

STPBRK command is requested)

In order to avoid unpredictable states:

• STTBRK and STPBRK commands must not be requested at the same time

• Once an STTBRK command is requested, further STTBRK commands are ignored

until the BREAK is ended (high level for at least 12-bit periods)

• All STPBRK commands requested without a previous STTBRK command are

ignored

• A byte written into the Transmit Holding Register while a break is pending but not

started (US_CSR.TXRDY = 0) is ignored

•It is

not permitted

to write new data in the Transmit Holding Register while a break is

in progress (STPBRK has not been requested), even though TXRDY = 1 in

US_CSR.

• A new STTBRK command

must not

be issued until an existing break has ended

(TXEMPTY = 1 in US_CSR)

The standard break transmission sequence is:

1. Wait for the transmitter ready

(US_CSR.TXRDY = 1)

2. Send the STTBRK command

(write 0x0200 to US_CR)

3. Wait for the transmitter ready

(TXRDY = 1 in US_CSR)

4. Send the STPBRK command

(write 0x0400 to US_CR)

The next byte can then be sent:

5. Wait for the transmitter ready

(TXRDY = 1 in US_CSR)

6. Send the next byte

(write byte to US_THR)

105

AT91X40 Series

1354D–ATARM–08/02

Each of these steps can be scheduled by using the interrupt if the bit TXRDY in US_IMR

is set. For character transmission, the USART channel must be enabled before sending

a break.

Receive Break The receiver detects a break condition when all data, parity and stop bits are low. When

the low stop bit is detected, the receiver asserts the RXBRK bit in US_CSR. An end of

receive break is detected by a high level for at least 2/16 of a bit period in Asynchronous

Mode or at least one sample in Synchronous Mode. RXBRK is also asserted when an

end of break is detected.

Both the beginning and the end of a break can be detected by interrupt if the bit

US_IMR.RXBRK is set.

Peripheral Data

Controller

Each USART channel is closely connected to a corresponding Peripheral Data Control-

ler channel. One is dedicated to the receiver. The other is dedicated to the transmitter.

Note: The PDC is disabled if 9-bit character length is selected (MODE9 = 1) in US_MR.

The PDC channel is programmed using US_TPR (Transmit Pointer) and US_TCR

(Transmit Counter) for the transmitter and US_RPR (Receive Pointer) and US_RCR

(Receive Counter) for the receiver. The status of the PDC is given in US_CSR by the

ENDTX bit for the transmitter and by the ENDRX bit for the receiver.

The pointer registers (US_TPR and US_RPR) are used to store the address of the

transmit or receive buffers. The counter registers (US_TCR and US_RCR) are used to

store the size of these buffers.

The receiver data transfer is triggered by the RXRDY bit and the transmitter data trans-

fer is triggered by TXRDY. When a transfer is performed, the counter is decremented

and the pointer is incremented. When the counter reaches 0, the status bit is set

(ENDRX for the receiver, ENDTX for the transmitter in US_CSR) which can be pro-

grammed to generate an interrupt. Transfers are then disabled until a new non-zero

counter value is programmed.

Interrupt Generation Each status bit in US_CSR has a corresponding bit in US_IER (Interrupt Enable) and

US_IDR (Interrupt Disable) which controls the generation of interrupts by asserting the

USART interrupt line connected to the Advanced Interrupt Controller. US_IMR (Interrupt

Mask Register) indicates the status of the corresponding bits.

When a bit is set in US_CSR and the same bit is set in US_IMR, the interrupt line is

asserted.

Channel Modes The USART can be programmed to operate in three different test modes, using the field

CHMODE in US_MR.

Automatic Echo Mode allows bit by bit re-transmission. When a bit is received on the

RXD line, it is sent to the TXD line. Programming the transmitter has no effect.

Local Loopback Mode allows the transmitted characters to be received. TXD and RXD

pins are not used and the output of the transmitter is internally connected to the input of

the receiver. The RXD pin level has no effect and the TXD pin is held high, as in idle

state.

Remote Loopback Mode directly connects the RXD pin to the TXD pin. The Transmitter

and the Receiver are disabled and have no effect. This mode allows bit by bit re-

transmission.

106 AT91X40 Series

1354D–ATARM–08/02

Figure 42. Channel Modes

Receiver

Transmitter Disabled

RXD

TXD

Receiver

Transmitter Disabled

RXD

TXD

VDD

Disabled

Receiver

Transmitter Disabled

RXD

TXD

Disabled

Automatic Echo

Local Loopback

Remote Loopback VDD

107

AT91X40 Series

1354D–ATARM–08/02

USART User Interface

Base Address USART0: 0xFFFD0000 (Code Label USART0_BASE)

Base Address USART1: 0xFFFCC000 (Code Label USART1_BASE)

Table 15. USART Memory Map

Offset Register Name Access Reset State

0x00 Control Register US_CR Write Only –

0x04 Mode Register US_MR Read/Write 0

0x08 Interrupt Enable Register US_IER Write Only –

0x0C Interrupt Disable Register US_IDR Write Only –

0x10 Interrupt Mask Register US_IMR Read Only 0

0x14 Channel Status Register US_CSR Read Only 0x18

0x18 Receiver Holding Register US_RHR Read Only 0

0x1C Transmitter Holding Register US_THR Write Only –

0x20 Baud Rate Generator Register US_BRGR Read/Write 0

0x24 Receiver Time-out Register US_RTOR Read/Write 0

0x28 Transmitter Time-guard Register US_TTGR Read/Write 0

0x2C Reserved – – –

0x30 Receive Pointer Register US_RPR Read/Write 0

0x34 Receive Counter Register US_RCR Read/Write 0

0x38 Transmit Pointer Register US_TPR Read/Write 0

0x3C Transmit Counter Register US_TCR Read/Write 0

108 AT91X40 Series

1354D–ATARM–08/02

USART Control Register

Name:US_CR

Access Type:Write Only

Offset: 0x00

• RSTRX: Reset Receiver (Code Label US_RSTRX)

0 = No effect.

1 = The receiver logic is reset.

• RSTTX: Reset Transmitter (Code Label US_RSTTX)

0 = No effect.

1 = The transmitter logic is reset.

• RXEN: Receiver Enable (Code Label US_RXEN)

0 = No effect.

1 = The receiver is enabled if RXDIS is 0.

• RXDIS: Receiver Disable (Code Label US_RXDIS)

0 = No effect.

1 = The receiver is disabled.

• TXEN: Transmitter Enable (Code Label US_TXEN)

0 = No effect.

1 = The transmitter is enabled if TXDIS is 0.

• TXDIS: Transmitter Disable (Code Label US_TXDIS)

0 = No effect.

1 = The transmitter is disabled.

• RSTSTA: Reset Status Bits (Code Label US_RSTSTA)

0 = No effect.

1 = Resets the status bits PARE, FRAME, OVRE and RXBRK in the US_CSR.

• STTBRK: Start Break (Code Label US_STTBRK)

0 = No effect.

1 = If break is not being transmitted, start transmission of a break after the characters present in US_THR and the Transmit

Shift Register have been transmitted.

• STPBRK: Stop Break (Code Label US_STPBRK)

0 = No effect.

1 = If a break is being transmitted, stop transmission of the break after a minimum of one character length and transmit a

high level during 12 bit periods.

31 30 29 28 27 26 25 24

––––––––

23 22 21 20 19 18 17 16

––––––––

15 14 13 12 11 10 9 8

–––

SENDA STTTO STPBRK STTBRK RSTSTA

76543210

TXDIS TXEN RXDIS RXEN RSTTX RSTRX ––

109

AT91X40 Series

1354D–ATARM–08/02

• STTTO: Start Time-out (Code Label US_STTTO)

0 = No effect.

1 = Start waiting for a character before clocking the time-out counter.

• SENDA: Send Address (Code Label US_SENDA)

0 = No effect.

1 = In Multi-drop Mode only, the next character written to the US_THR is sent with the address bit set.

110 AT91X40 Series

1354D–ATARM–08/02

USART Mode Register

Name:US_MR

Access Type:Read/Write

Reset Value:0

Offset: 0x04

• USCLKS: Clock Selection (Baud Rate Generator Input Clock)

• CHRL: Character Length

Start, stop and parity bits are added to the character length.

• SYNC: Synchronous Mode Select (Code Label US_SYNC)

0 = USART operates in Asynchronous Mode.

1 = USART operates in Synchronous Mode.

31 30 29 28 27 26 25 24

––––––––

23 22 21 20 19 18 17 16

–––––

CLKO MODE9 –

15 14 13 12 11 10 9 8

CHMODE NBSTOP PAR SYNC

76543210

CHRL USCLKS ––––

USCLKS Selected Clock

Code Label

US_CLKS

00MCK US_CLKS_MCK

01MCK/8 US_CLKS_MCK8

1 X External (SCK) US_CLKS_SCK

CHRL Character Length

Code Label

US_CHRL

0 0 Five bits US_CHRL_5

01Six bits US_CHRL_6

1 0 Seven bits US_CHRL_7

1 1 Eight bits US_CHRL_8

111

AT91X40 Series

1354D–ATARM–08/02

• PAR: Parity Type

• NBSTOP: Number of Stop Bits

The interpretation of the number of stop bits depends on SYNC.

• CHMODE: Channel Mode

• MODE9: 9-bit Character Length (Code Label US_MODE9)

0 = CHRL defines character length.

1 = 9-bit character length.

• CKLO: Clock Output Select (Code Label US_CLKO)

0 = The USART does not drive the SCK pin.

1 = The USART drives the SCK pin if USCLKS[1] is 0.

PAR Pa ri ty Typ e

Code Label

US_PAR

000Even Parity US_PAR_EVEN

001Odd Parity US_PAR_ODD

0 1 0 Parity forced to 0 (Space) US_PAR_SPACE

0 1 1 Parity forced to 1 (Mark) US_PAR_MARK

1 0 x No parity US_PAR_NO

1 1 x Multi-drop mode US_PAR_MULTIDROP

NBSTOP Asynchronous (SYNC = 0) Synchronous (SYNC = 1)

Code Label

US_NBSTOP

0 0 1 stop bit 1 stop bit US_NBSTOP_1

0 1 1.5 stop bits Reserved US_NBSTOP_1_5

1 0 2 stop bits 2 stop bits US_NBSTOP_2

1 1 Reserved Reserved –

CHMODE Mode Description

Code Label

US_CHMODE

Normal Mode

The USART Channel operates as an Rx/Tx USART. US_CHMODE_NORMAL

Automatic Echo

Receiver Data Input is connected to TXD pin. US_CHMODE_AUTOMATIC_ECHO

Local Loopback

Transmitter Output Signal is connected to Receiver Input Signal. US_CHMODE_LOCAL_LOOPBACK

Remote Loopback

RXD pin is internally connected to TXD pin. US_CHMODE_REMODE_LOOPBACK

112 AT91X40 Series

1354D–ATARM–08/02

USART Interrupt Enable Register

Name:US_IER

Access Type:Write Only

Offset:0x08

• RXRDY: Enable RXRDY Interrupt (Code Label US_RXRDY)

0 = No effect.

1 = Enables RXRDY Interrupt.

• TXRDY: Enable TXRDY Interrupt (Code Label US_TXRDY)

0 = No effect.

1 = Enables TXRDY Interrupt.

• RXBRK: Enable Receiver Break Interrupt (Code Label US_RXBRK)

0 = No effect.

1 = Enables Receiver Break Interrupt.

• ENDRX: Enable End of Receive Transfer Interrupt (Code Label US_ENDRX)

0 = No effect.

1 = Enables End of Receive Transfer Interrupt.

• ENDTX: Enable End of Transmit Interrupt (Code Label US_ENDTX)

0 = No effect.

1 = Enables End of Transmit Interrupt.

• OVRE: Enable Overrun Error Interrupt (Code Label US_OVRE)

0 = No effect.

1 = Enables Overrun Error Interrupt.

• FRAME: Enable Framing Error Interrupt (Code Label US_FRAME)

0 = No effect.

1 = Enables Framing Error Interrupt.

• PARE: Enable Parity Error Interrupt (Code Label US_PARE)

0 = No effect.

1 = Enables Parity Error Interrupt.

• TIMEOUT: Enable Time-out Interrupt (Code Label US_TIMEOUT)

0 = No effect.

1 = Enables Reception Time-out Interrupt.

• TXEMPTY: Enable TXEMPTY Interrupt (Code Label US_TXEMPTY)

0 = No effect.

1 = Enables TXEMPTY Interrupt.

31 30 29 28 27 26 25 24

––––––––

23 22 21 20 19 18 17 16

––––––––

15 14 13 12 11 10 9 8

––––––

TXEMPTY TIMEOUT

76543210

PARE FRAME OVRE ENDTX ENDRX RXBRK TXRDY RXRDY

113

AT91X40 Series

1354D–ATARM–08/02

USART Interrupt Disable Register

Name:US_IDR

Access Type:Write Only

Offset:0x0C

• RXRDY: Disable RXRDY Interrupt (Code Label US_RXRDY)

0 = No effect.

1 = Disables RXRDY Interrupt.

• TXRDY: Disable TXRDY Interrupt (Code Label US_TXRDY)

0 = No effect.

1 = Disables TXRDY Interrupt.

• RXBRK: Disable Receiver Break Interrupt (Code Label US_RXBRK)

0 = No effect.

1 = Disables Receiver Break Interrupt.

• ENDRX: Disable End of Receive Transfer Interrupt (Code Label US_ENDRX)

0 = No effect.

1 = Disables End of Receive Transfer Interrupt.

• ENDTX: Disable End of Transmit Interrupt (Code Label US_ENDTX)

0 = No effect.

1 = Disables End of Transmit Interrupt.

• OVRE: Disable Overrun Error Interrupt (Code Label US_OVRE)

0 = No effect.

1 = Disables Overrun Error Interrupt.

• FRAME: Disable Framing Error Interrupt (Code Label US_FRAME)

0 = No effect.

1 = Disables Framing Error Interrupt.

• PARE: Disable Parity Error Interrupt (Code Label US_PARE)

0 = No effect.

1 = Disables Parity Error Interrupt.

• TIMEOUT: Disable Time-out Interrupt (Code Label US_TIMEOUT)

0 = No effect.

1 = Disables Receiver Time-out Interrupt.

• TXEMPTY: Disable TXEMPTY Interrupt (Code Label US_TXEMPTY)

0 = No effect.

1 = Disables TXEMPTY Interrupt.

31 30 29 28 27 26 25 24

––––––––

23 22 21 20 19 18 17 16

––––––––

15 14 13 12 11 10 9 8

––––––

TXEMPTY TIMEOUT

76543210

PARE FRAME OVRE ENDTX ENDRX RXBRK TXRDY RXRDY

114 AT91X40 Series

1354D–ATARM–08/02

USART Interrupt Mask Register

Name:US_IMR

Access Type:Read Only

Reset Value:0

Offset:0x10

• RXRDY: Mask RXRDY Interrupt (Code Label US_RXRDY)

0 = RXRDY Interrupt is Disabled

1 = RXRDY Interrupt is Enabled

• TXRDY: Mask TXRDY Interrupt (Code Label US_TXRDY)

0 = TXRDY Interrupt is Disabled

1 = TXRDY Interrupt is Enabled

• RXBRK: Mask Receiver Break Interrupt (Code Label US_RXBRK)

0 = Receiver Break Interrupt is Disabled

1 = Receiver Break Interrupt is Enabled

• ENDRX: Mask End of Receive Transfer Interrupt (Code Label US_ENDRX)

0 = End of Receive Transfer Interrupt is Disabled

1 = End of Receive Transfer Interrupt is Enabled

• ENDTX: Mask End of Transmit Interrupt (Code Label US_ENDTX)

0 = End of Transmit Interrupt is Disabled

1 = End of Transmit Interrupt is Enabled

• OVRE: Mask Overrun Error Interrupt (Code Label US_OVRE)

0 = Overrun Error Interrupt is Disabled

1 = Overrun Error Interrupt is Enabled

• FRAME: Mask Framing Error Interrupt (Code Label US_FRAME)

0 = Framing Error Interrupt is Disabled

1 = Framing Error Interrupt is Enabled

• PARE: Mask Parity Error Interrupt (Code Label US_PARE)

0 = Parity Error Interrupt is Disabled

1 = Parity Error Interrupt is Enabled

• TIMEOUT: Mask Time-out Interrupt (Code Label US_TIMEOUT)

0 = Receive Time-out Interrupt is Disabled

1 = Receive Time-out Interrupt is Enabled

• TXEMPTY: Mask TXEMPTY Interrupt (Code Label US_TXEMPTY)

0 = TXEMPTY Interrupt is Disabled.

1 = TXEMPTY Interrupt is Enabled.

31 30 29 28 27 26 25 24

––––––––

23 22 21 20 19 18 17 16

––––––––

15 14 13 12 11 10 9 8

––––––

TXEMPTY TIMEOUT

76543210

PARE FRAME OVRE ENDTX ENDRX RXBRK TXRDY RXRDY

115

AT91X40 Series

1354D–ATARM–08/02

USART Channel Status Register

Name:US_CSR

Access Type:Read Only

Reset Value:0x18

Offset: 0x14

• RXRDY: Receiver Ready (Code Label US_RXRDY)

0 = No complete character has been received since the last read of the US_RHR or the receiver is disabled.

1 = At least one complete character has been received and the US_RHR has not yet been read.

• TXRDY: Transmitter Ready (Code Label US_TXRDY)

0 = US_THR contains a character waiting to be transferred to the Transmit Shift Register, or an STTBRK command has

been requested.

1 = US_THR is empty and there is no Break request pending TSR availability.

Equal to zero when the USART is disabled or at reset. Transmitter Enable command (in US_CR) sets this bit to one.

• RXBRK: Break Received/End of Break (Code Label US_RXBRK)

0 = No Break Received nor End of Break has been detected since the last “Reset Status Bits” command in the Control

1 = Break Received or End of Break has been detected since the last “Reset Status Bits” command in the Control Register.

• ENDRX: End of Receiver Transfer (Code Label US_ENDRX)

0 = The End of Transfer signal from the Peripheral Data Controller channel dedicated to the receiver is inactive.

1 = The End of Transfer signal from the Peripheral Data Controller channel dedicated to the receiver is active.

• ENDTX: End of Transmitter Transfer (Code Label US_ENDTX)

0 = The End of Transfer signal from the Peripheral Data Controller channel dedicated to the transmitter is inactive.

1 = The End of Transfer signal from the Peripheral Data Controller channel dedicated to the transmitter is active.

• OVRE: Overrun Error (Code Label US_OVRE)

0 = No byte has been transferred from the Receive Shift Register to the US_RHR when RxRDY was asserted since the last

“Reset Status Bits” command.

1 = At least one byte has been transferred from the Receive Shift Register to the US_RHR when RxRDY was asserted

since the last “Reset Status Bits” command.

• FRAME: Framing Error (Code Label US_FRAME)

0 = No stop bit has been detected low since the last “Reset Status Bits” command.

1 = At least one stop bit has been detected low since the last “Reset Status Bits” command.

31 30 29 28 27 26 25 24

––––––––

23 22 21 20 19 18 17 16

––––––––

15 14 13 12 11 10 9 8

––––––

TXEMPTY TIMEOUT

76543210

PARE FRAME OVRE ENDTX ENDRX RXBRK TXRDY RXRDY

116 AT91X40 Series

1354D–ATARM–08/02

• PARE: Parity Error (Code Label US_PARE)

1 = At least one parity bit has been detected false (or a parity bit high in Multi-drop Mode) since the last “Reset Status Bits”

command.

0 = No parity bit has been detected false (or a parity bit high in Multi-drop Mode) since the last “Reset Status Bits”

command.

• TIMEOUT: Receiver Time-out (Code Label US_TIMEOUT)

0 = There has not been a time-out since the last “Start Time-out” command or the Time-out Register is 0.

1 = There has been a time-out since the last “Start Time-out” command.

• TXEMPTY: Transmitter Empty (Code Label US_TXEMPTY)

0 = There are characters in either US_THR or the Transmit Shift Register or a Break is being transmitted.

1 = There are no characters in US_THR and the Transmit Shift Register and Break is not active.

Equal to zero when the USART is disabled or at reset. Transmitter Enable command (in US_CR) sets this bit to one.

117

AT91X40 Series

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USART Receiver Holding Register

Name: US_RHR

Access Type:Read Only

Reset Value:0

Offset: 0x18

• RXCHR: Received Character

Last character received if RXRDY is set. When number of data bits is less than 8 bits, the bits are right-aligned.

All non-significant bits read zero.

USART Transmitter Holding Register

Name:US_THR

Access Type:Write Only

Offset:0x1C

• TXCHR: Character to be Transmitted

Next character to be transmitted after the current character if TXRDY is not set. When number of data bits is less than 8

bits, the bits are right-aligned.

31 30 29 28 27 26 25 24

––––––––

23 22 21 20 19 18 17 16

––––––––

15 14 13 12 11 10 9 8

––––––––

76543210

RXCHR

31 30 29 28 27 26 25 24

––––––––

23 22 21 20 19 18 17 16

––––––––

15 14 13 12 11 10 9 8

––––––––

76543210

TXCHR

118 AT91X40 Series

1354D–ATARM–08/02

USART Baud Rate Generator Register

Name: US_BRGR

Access Type:Read/Write

Reset Value:0

Offset: 0x20

• CD: Clock Divisor

This register has no effect if Synchronous Mode is selected with an external clock.

Notes: 1. Clock divisor bypass (CD = 1) must not be used when internal clock MCK is selected (USCLKS = 0).

2. In Synchronous Mode, the value programmed must be even to ensure a 50:50 mark:space ratio.

31 30 29 28 27 26 25 24

––––––––

23 22 21 20 19 18 17 16

––––––––

15 14 13 12 11 10 9 8

76543210

CD Effect

0 Disables Clock

1 Clock Divisor Bypass (1)

2 to 65535 Baud Rate (Asynchronous Mode) = Selected Clock / (16 x CD)

Baud Rate (Synchronous Mode) = Selected Clock / CD (2)

119

AT91X40 Series

1354D–ATARM–08/02

USART Receiver Time-out Register

Name:US_RTOR

Access Type:Read/Write

Reset Value:0

Offset: 0x24

• TO: Time-out Value

When a value is written to this register, a Start Time-out Command is automatically performed.

Time-out duration = TO x 4 x Bit period

USART Transmitter Time-guard Register

Name: US_TTGR

Access Type:Read/Write

Reset Value:0

Offset: 0x28

• TG: Time-guard Value

Time-guard duration = TG x Bit period

31 30 29 28 27 26 25 24

––––––––

23 22 21 20 19 18 17 16

––––––––

15 14 13 12 11 10 9 8

––––––––

76543210

0 Disables the RX Time-out function.

1 - 255 The Time-out counter is loaded with TO when the Start Time-out Command is given or when each new data character is

received (after reception has started).

31 30 29 28 27 26 25 24

––––––––

23 22 21 20 19 18 17 16

––––––––

15 14 13 12 11 10 9 8

––––––––

76543210

0 Disables the TX Time-guard function.

1 - 255 TXD is inactive high after the transmission of each character for the time-guard duration.

120 AT91X40 Series

1354D–ATARM–08/02

USART Receive Pointer Register

Name:US_RPR

Access Type:Read/Write

Reset Value:0

Offset: 0x30

• RXPTR: Receive Pointer

RXPTR must be loaded with the address of the receive buffer.

USART Receive Counter Register

Name: US_RCR

Access Type:Read/Write

Reset Value:0

Offset:0x34

• RXCTR: Receive Counter

RXCTR must be loaded with the size of the receive buffer.

0: Stop Peripheral Data Transfer dedicated to the receiver.

1 - 65535: Start Peripheral Data transfer if RXRDY is active.

31 30 29 28 27 26 25 24

RXPTR

23 22 21 20 19 18 17 16

RXPTR

15 14 13 12 11 10 9 8

RXPTR

76543210

RXPTR

31 30 29 28 27 26 25 24

––––––––

23 22 21 4920 19 18 17 16

––––––––

15 14 13 12 11 10 9 8

RXCTR

76543210

RXCTR

121

AT91X40 Series

1354D–ATARM–08/02

USART Transmit Pointer Register

Name:US_TPR

Access Type:Read/Write

Reset Value:0

Offset:0x38

• TXPTR: Transmit Pointer

TXPTR must be loaded with the address of the transmit buffer.

USART Transmit Counter Register

Name:US_TCR

Access Type:Read/Write

Reset Value:0

Offset:0x3C

• TXCTR: Transmit Counter

TXCTR must be loaded with the size of the transmit buffer.

0: Stop Peripheral Data Transfer dedicated to the transmitter.

1 - 65535: Start Peripheral Data transfer if TXRDY is active.

31 30 29 28 27 26 25 24

TXPTR

23 22 21 20 19 18 17 16

TXPTR

15 14 13 12 11 10 9 8

TXPTR

76543210

TXPTR

31 30 29 28 27 26 25 24

––––––––

23 22 21 20 19 18 17 16

––––––––

15 14 13 12 11 10 9 8

TXCTR

76543210

TXCTR

122 AT91X40 Series

1354D–ATARM–08/02

TC: Timer Counter The AT91X40 Series features a Timer Counter block which includes three identical 16-

bit timer counter channels. Each channel can be independently programmed to perform

a wide range of functions including frequency measurement, event counting, interval

measurement, pulse generation, delay timing and pulse width modulation.

Each Timer Counter channel has 3 external clock inputs, 5 internal clock inputs, and 2

multi-purpose input/output signals which can be configured by the user. Each channel

drives an internal interrupt signal which can be programmed to generate processor

interrupts via the AIC (Advanced Interrupt Controller).

The Timer Counter block has two global registers which act upon all three TC channels.

The Block Control Register allows the three channels to be started simultaneously with

the same instruction. The Block Mode Register defines the external clock inputs for

each Timer Counter channel, allowing them to be chained.

Figure 43. TC Block Diagram

Timer Counter

Channel 0

Timer Counter

Channel 1

Timer Counter

Channel 2

SYNC

Parallel IO

Controller

TC1XC1S

TC0XC0S

TC2XC2S

INT

TIOA0

TIOA1

TIOA2

TIOB0

TIOB1

TIOB2

XC0

XC1

XC2

XC0

XC1

XC2

XC0

XC1

XC2

TCLK0

TCLK1

TCLK2

TCLK0

TCLK1

TCLK2

TCLK0

TCLK1

TCLK2

TIOA1

TIOA2

TIOA0

TIOA2

TIOA0

TIOA1

Advanced

Interrupt

Controller

TCLK0

TCLK1

TCLK2

TIOA0

TIOB0

TIOA1

TIOB1

TIOA2

TIOB2

Timer Counter Block

TIOA

TIOB

TIOA

TIOB

TIOA

TIOB

SYNC

MCK/2

MCK/8

MCK/32

MCK/128

MCK/1024

123

AT91X40 Series

1354D–ATARM–08/02

Signal Name Description

Note: After a hardware reset, the Timer Counter block pins are controlled by the PIO Controller. They must be configured to be con-

trolled by the peripheral before being used.

Timer Counter

Description

The three Timer Counter channels are independent and identical in operation. The reg-

isters for channel programming are listed in Table 17.

Counter Each Timer Counter channel is organized around a 16-bit counter. The value of the

counter is incremented at each positive edge of the selected clock. When the counter

has reached the value 0xFFFF and passes to 0x0000, an overflow occurs and the bit

COVFS in TC_SR (Status Register) is set.

The current value of the counter is accessible in real-time by reading TC_CV. The

counter can be reset by a trigger. In this case, the counter value passes to 0x0000 on

the next valid edge of the selected clock.

Clock Selection At block level, input clock signals of each channel can either be connected to the exter-

nal inputs TCLK0, TCLK1 or TCLK2, or be connected to the configurable I/O signals

TIOA0, TIOA1 or TIOA2 for chaining by programming the TC_BMR (Block Mode).

Each channel can independently select an internal or external clock source for its

counter:

• Internal clock signals: MCK/2, MCK/8, MCK/32,

MCK/128, MCK/1024

• External clock signals: XC0, XC1 or XC2

Channel Signal Description

XC0, XC1, XC2 External Clock Inputs

TIOA Capture Mode: General Purpose Input

Waveform Mode: General Purpose Output

TIOB Capture Mode: General Purpose Input

Waveform Mode: General Purpose Input/Output

INT Interrupt Signal Output

SYNC Synchronization Input Signal

Block Signals Description

TCLK0, TCLK1, TCLK2 External Clock Inputs

TIOA0 TIOA Signal for Channel 0

TIOB0 TIOB Signal for Channel 0

TIOA1 TIOA Signal for Channel 1

TIOB1 TIOB Signal for Channel 1

TIOA2 TIOA Signal for Channel 2

TIOB2 TIOB Signal for Channel 2

124 AT91X40 Series

1354D–ATARM–08/02

The selected clock can be inverted with the CLKI bit in TC_CMR (Channel Mode). This

allows counting on the opposite edges of the clock.

The burst function allows the clock to be validated when an external signal is high. The

BURST parameter in the Mode Register defines this signal (none, XC0, XC1, XC2).

Note: In all cases, if an external clock is used, the duration of each of its levels must be longer

than the system clock (MCK) period. The external clock frequency must be at least 2.5

times lower than the system clock (MCK).

Figure 44. Clock Selection

Clock Control The clock of each counter can be controlled in two different ways: it can be enabled/dis-

abled and started/stopped.

• The clock can be enabled or disabled by the user with the CLKEN and the CLKDIS

commands in the Control Register. In Capture Mode it can be disabled by an RB

load event if LDBDIS is set to 1 in TC_CMR. In Waveform Mode, it can be disabled

by an RC Compare event if CPCDIS is set to 1 in TC_CMR. When disabled, the

start or the stop actions have no effect: only a CLKEN command in the Control

in the Status Register.

• The clock can also be started or stopped: a trigger (software, synchro, external or

compare) always starts the clock. The clock can be stopped by an RB load event in

Capture Mode (LDBSTOP = 1 in TC_CMR) or a RC compare event in Waveform

Mode (CPCSTOP = 1 in TC_CMR). The start and the stop commands have effect

only if the clock is enabled.

MCK/2

MCK/8

MCK/32

MCK/128

MCK/1024

XC0

XC1

XC2

CLKS

CLKI

BURST

Selected

Clock

125

AT91X40 Series

1354D–ATARM–08/02

Figure 45. Clock Control

Timer Counter Operating

Modes

Each Timer Counter channel can independently operate in two different modes:

• Capture Mode allows measurement on signals

• Waveform Mode allows wave generation

The Timer Counter Operating Mode is programmed with the WAVE bit in the TC Mode

Mode, TIOA is always configured to be an output and TIOB is an output if it is not

selected to be the external trigger.

Trigger A trigger resets the counter and starts the counter clock. Three types of triggers are

common to both modes, and a fourth external trigger is available to each mode.

The following triggers are common to both modes:

• Software Trigger: Each channel has a software trigger, available by setting SWTRG

in TC_CCR.

• SYNC: Each channel has a synchronization signal SYNC. When asserted, this

signal has the same effect as a software trigger. The SYNC signals of all channels

are asserted simultaneously by writing TC_BCR (Block Control) with SYNC set.

• Compare RC Trigger: RC is implemented in each channel and can provide a trigger

when the counter value matches the RC value if CPCTRG is set in TC_CMR.

The Timer Counter channel can also be configured to have an external trigger. In Cap-

ture Mode, the external trigger signal can be selected between TIOA and TIOB. In

Waveform Mode, an external event can be programmed on one of the following signals:

TIOB, XC0, XC1 or XC2. This external event can then be programmed to perform a trig-

ger by setting ENETRG in TC_CMR.

If an external trigger is used, the duration of the pulses must be longer than the system

clock (MCK) period in order to be detected.

Whatever the trigger used, it will be taken into account at the following active edge of the

selected clock. This means that the counter value may not read zero just after a trigger,

especially when a low frequency signal is selected as the clock.

CLKSTA CLKEN CLKDIS

Stop

Event

Disable

Event

Counter

Clock

Selected

Clock Trigger

126 AT91X40 Series

1354D–ATARM–08/02

Capture Operating Mode This mode is entered by clearing the WAVE parameter in TC_CMR (Channel Mode

pulse timing, frequency, period, duty cycle and phase on TIOA and TIOB signals which

are inputs.

Figure 46 shows the configuration of the TC Channel when programmed in Capture

Mode.

Capture Registers A and B

(RA and RB)

Registers A and B are used as capture registers. This means that they can be loaded

with the counter value when a programmable event occurs on the signal TIOA.

The parameter LDRA in TC_CMR defines the TIOA edge for the loading of register A,

and the parameter LDRB defines the TIOA edge for the loading of Register B.

RA is loaded only if it has not been loaded since the last trigger or if RB has been loaded

since the last loading of RA.

RB is loaded only if RA has been loaded since the last trigger or the last loading of RB.

Loading RA or RB before the read of the last value loaded sets the Overrun Error Flag

(LOVRS) in TC_SR (Status Register). In this case, the old value is overwritten.

Trigger Conditions In addition to the SYNC signal, the software trigger and the RC compare trigger, an

external trigger can be defined.

Bit ABETRG in TC_CMR selects input signal TIOA or TIOB as an external trigger.

Parameter ETRGEDG defines the edge (rising, falling or both) detected to generate an

external trigger. If ETRGEDG = 0 (none), the external trigger is disabled.

Status Register The following bits in the status register are significant in Capture Operating Mode.

• CPCS: RC Compare Status

There has been an RC Compare match at least once since the last read of the

status

• COVFS: Counter Overflow Status

The counter has attempted to count past $FFFF since the last read of the status

• LOVRS: Load Overrun Status

RA or RB has been loaded at least twice without any read of the corresponding reg-

ister, since the last read of the status

• LDRAS: Load RA Status

RA has been loaded at least once without any read, since the last read of the status

• LDRBS: Load RB Status

RB has been loaded at least once without any read, since the last read of the status

• ETRGS: External Trigger Status

An external trigger on TIOA or TIOB has been detected since the last read of the

status

Note: All the status bits are set when the corresponding event occurs and they are automati-

cally cleared when the Status Register is read.

127

AT91X40 Series

1354D–ATARM–08/02

Figure 46. Capture Mode

MCK/2

MCK/8

MCK/32

MCK/128

MCK/1024

XC0

XC1

XC2

TCCLKS

CLKI

CLKSTA CLKEN CLKDIS

BURST

TIOB

Capture

16-bit Counter

ABETRG

SWTRG

ETRGEDG CPCTRG

TC_IMR

Trig

LDRBS

LDRAS

ETRGS

TC_SR

LOVRS

COVFS

SYNC

MTIOB

TIOA

MTIOA

LDRA

LDBSTOP

If RA is not loaded

or RB is loaded If RA is loaded

LDBDIS

CPCS

INT

Edge

Detector

Edge

Detector

LDRB

Edge

Detector

CLK

OVF

RESET

Timer Counter Channel

128 AT91X40 Series

1354D–ATARM–08/02

Waveform Operating

Mode

This mode is entered by setting the WAVE parameter in TC_CMR (Channel Mode

Waveform Operating Mode allows the TC Channel to generate 1 or 2 PWM signals with

the same frequency and independently programmable duty cycles, or to generate differ-

ent types of one-shot or repetitive pulses.

In this mode, TIOA is configured as output and TIOB is defined as output if it is not used

as an external event (EEVT parameter in TC_CMR).

Figure 47 shows the configuration of the TC Channel when programmed in Waveform

Operating Mode.

Compare Register A, B and C

(RA, RB, and RC)

In Waveform Operating Mode, RA, RB and RC are all used as compare registers.

RA Compare is used to control the TIOA output. RB Compare is used to control the

TIOB (if configured as output). RC Compare can be programmed to control TIOA and/or

TIOB outputs.

RC Compare can also stop the counter clock (CPCSTOP = 1 in TC_CMR) and/or dis-

able the counter clock (CPCDIS = 1 in TC_CMR).

As in Capture Mode, RC Compare can also generate a trigger if CPCTRG = 1. A trigger

resets the counter so RC can control the period of PWM waveforms.

External Event/Trigger Conditions

An external event can be programmed to be detected on one of the clock sources (XC0,

XC1, XC2) or TIOB. The external event selected can then be used as a trigger.

The parameter EEVT in TC_CMR selects the external trigger. The parameter EEVT-

EDG defines the trigger edge for each of the possible external triggers (rising, falling or

both). If EEVTEDG is cleared (none), no external event is defined.

If TIOB is defined as an external event signal (EEVT = 0), TIOB is no longer used as

output and the TC channel can only generate a waveform on TIOA.

When an external event is defined, it can be used as a trigger by setting bit ENETRG in

TC_CMR.

As in Capture Mode, the SYNC signal, the software trigger and the RC compare trigger

are also available as triggers.

129

AT91X40 Series

1354D–ATARM–08/02

Output Controller The output controller defines the output level changes on TIOA and TIOB following an

event. TIOB control is used only if TIOB is defined as output (not as an external event).

The following events control TIOA and TIOB: software trigger, external event and RC

compare. RA compare controls TIOA and RB compare controls TIOB. Each of these

events can be programmed to set, clear or toggle the output as defined in the corre-

sponding parameter in TC_CMR.

The tables below show which parameter in TC_CMR is used to define the effect of each

event.

If two or more events occur at the same time, the priority level is defined as follows:

1. Software Trigger

2. External Event

3. RC Compare

4. RA or RB Compare

Status The following bits in the status register are significant in Waveform Mode:

• CPAS: RA Compare Status

There has been a RA Compare match at least once since the last read of the status

• CPBS: RB Compare Status

There has been a RB Compare match at least once since the last read of the status

• CPCS: RC Compare Status

There has been a RC Compare match at least once since the last read of the status

• COVFS: Counter Overflow

Counter has attempted to count past $FFFF since the last read of the status

• ETRGS: External Trigger

External trigger has been detected since the last read of the status

Note: All the status bits are set when the corresponding event occurs and they are automati-

cally cleared when the Status Register is read.

Parameter TIOA Event

ASWTRG Software Trigger

AEEVT External Event

ACPC RC Compare

ACPA RA Compare

Parameter TIOB Event

BSWTRG Software Trigger

BEEVT External Event

BCPC RC Compare

BCPB RB Compare

130 AT91X40 Series

1354D–ATARM–08/02

Figure 47. Waveform Mode

MCK/2

MCK/8

MCK/32

MCK/128

MCK/1024

XC0

XC1

XC2

TCCLKS

CLKI

CLKSTA CLKEN CLKDIS

CPCDIS

BURST

TIOB

Compare RA = Compare RB = Compare RC =

CPCSTOP

16-bit Counter

EEVT

EEVTEDG

SYNC

SWTRG

ENETRG

CPCTRG

TC_IMR

Trig

ACPC

ACPA

AEEVT

ASWTRG

BCPC

BCPB

BEEVT

BSWTRG

TIOA

MTIOA

TIOB

MTIOB

CPAS

COVFS

ETRGS

TC_SR

CPCS

CPBS

CLK

OVF

RESET

Output Controller

INT

Edge

Detector

Timer Counter Channel

131

AT91X40 Series

1354D–ATARM–08/02

TC User Interface

TC Base Address: 0xFFFE0000 (Code Label TC_BASE)

TC_BCR (Block Control Register) and TC_BMR (Block Mode Register) control the TC block. TC Channels are controlled

by the registers listed in Table 17. The offset of each of the Channel registers in Table 17 is in relation to the offset of the

corresponding channel as mentioned in Table 16.

Note: Read Only if WAVE = 0

Table 16. TC Global Memory Map

Offset Channel/Register Name Access Reset State

0x00 TC Channel 0 See Table 17

0x40 TC Channel 1 See Table 17

0x80 TC Channel 2 See Table 17

0xC0 TC Block Control Register TC_BCR Write Only –

0xC4 TC Block Mode Register TC_BMR Read/Write 0

Table 17. TC Channel Memory Map

Offset Register Name Access Reset State

0x00 Channel Control Register TC_CCR Write Only –

0x04 Channel Mode Register TC_CMR Read/Write 0

0x08 Reserved –

0x0C Reserved –

0x10 Counter Value TC_CV Read/Write 0

0x14 Register A TC_RA Read/Write(1) 0

0x18 Register B TC_RB Read/Write(1) 0

0x1C Register C TC_RC Read/Write 0

0x20 Status Register TC_SR Read Only 0

0x24 Interrupt Enable Register TC_IER Write Only –

0x28 Interrupt Disable Register TC_IDR Write Only –

0x2C Interrupt Mask Register TC_IMR Read Only 0

132 AT91X40 Series

1354D–ATARM–08/02

TC Block Control Register

Access Type: Write only

Offset:0xC0

• SYNC: Synchro Command

0 = No effect.

1 = Asserts the SYNC signal which generates a software trigger simultaneously for each of the channels.

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–––––––

SYNC

133

AT91X40 Series

1354D–ATARM–08/02

TC Block Mode Register

Access Type: Read/Write

Reset Value:0

Offset:0xC4

• TC0XC0S: External Clock Signal 0 Selection

• TC1XC1S: External Clock Signal 1 Selection

• TC2XC2S: External Clock Signal 2 Selection

31 30 29 28 27 26 25 24

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15 14 13 12 11 10 9 8

––––––––

76543210

–– TC2XC2S TC1XC1S TC0XC0S

TC0XC0S Signal Connected to XC0

00TCLK0

0 1 None

10TIOA1

11TIOA2

TC1XC1S Signal Connected to XC1

00TCLK1

01None

10TIOA0

11TIOA2

TC2XC2S Signal Connected to XC2

00TCLK2

0 1 None

10TIOA0

11TIOA1

134 AT91X40 Series

1354D–ATARM–08/02

TC Channel Control Register

Access Type: Write only

Offset: 0x00

• CLKEN: Counter Clock Enable Command (Code Label TC_CLKEN)

0 = No effect.

1 = Enables the clock if CLKDIS is not 1.

• CLKDIS: Counter Clock Disable Command (Code Label TC_CLKDIS)

0 = No effect.

1 = Disables the clock.

• SWTRG: Software Trigger Command (Code Label TC_SWTRG)

0 = No effect.

1 = A software trigger is performed: the counter is reset and clock is started.

31 30 29 28 27 26 25 24

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–––––

SWTRG CLKDIS CLKEN

135

AT91X40 Series

1354D–ATARM–08/02

TC Channel Mode Register: Capture Mode

Access Type: Read/Write

Reset Value:0

Offset: 0x04

• TCCLKS: Clock Selection

• CLKI: Clock Invert (Code Label TC_CLKI)

0 = Counter is incremented on rising edge of the clock.

1 = Counter is incremented on falling edge of the clock.

• BURST: Burst Signal Selection

• LDBSTOP: Counter Clock Stopped with RB Loading (Code Label TC_LDBSTOP)

0 = Counter clock is not stopped when RB loading occurs.

1 = Counter clock is stopped when RB loading occurs.

31 30 29 28 27 26 25 24

––––––––

23 22 21 20 19 18 17 16

–––– LDRB LDRA

15 14 13 12 11 10 9 8

WAVE = 0 CPCTRG –––

ABETRG ETRGEDG

76543210

LDBDIS LDBSTOP BURST CLKI TCCLKS

TCCLKS Clock Selected

Code Label

TC_CLKS

000MCK/2 TC_CLKS_MCK2

001MCK/8 TC_CLKS_MCK8

010MCK/32 TC_CLKS_MCK32

011MCK/128 TC_CLKS_MCK128

100MCK/1024 TC_CLKS_MCK1024

101XC0 TC_CLKS_XC0

110XC1 TC_CLKS_XC1

111XC2 TC_CLKS_XC2

BURST Selected BURST

Code Label

TC_BURST

0 0 The clock is not gated by an external signal TC_BURST_NONE

0 1 XC0 is ANDed with the selected clock TC_BURST_XC0

1 0 XC1 is ANDed with the selected clock TC_BURST_XC1

1 1 XC2 is ANDed with the selected clock TC_BURST_XC2

136 AT91X40 Series

1354D–ATARM–08/02

• LDBDIS: Counter Clock Disable with RB Loading (Code Label TC_LDBDIS)

0 = Counter clock is not disabled when RB loading occurs.

1 = Counter clock is disabled when RB loading occurs.

• ETRGEDG: External Trigger Edge Selection

• ABETRG: TIOA or TIOB External Trigger Selection

• CPCTRG: RC Compare Trigger Enable (Code Label TC_CPCTRG)

0 = RC Compare has no effect on the counter and its clock.

1 = RC Compare resets the counter and starts the counter clock.

• WAVE = 0 (Code Label TC_WAVE)

0 = Capture Mode is enabled.

1 = Capture Mode is disabled (Waveform Mode is enabled).

• LDRA: RA Loading Selection

• LDRB: RB Loading Selection

ETRGEDG Edge

Code Label

TC_ETRGEDG

00None TC_ETRGEDG_EDGE_NONE

01Rising Edge TC_ETRGEDG_RISING_EDGE

1 0 Falling Edge TC_ETRGEDG_FALLING_EDGE

1 1 Each Edge TC_ETRGEDG_BOTH_EDGE

ABETRG Selected ABETRG

Code Label

TC_ABETRG

0 TIOB is used as an external trigger. TC_ABETRG_TIOB

1 TIOA is used as an external trigger. TC_ABETRG_TIOA

LDRA Edge

Code Label

TC_LDRA

00None TC_LDRA_EDGE_NONE

0 1 Rising edge of TIOA TC_LDRA_RISING_EDGE

1 0 Falling edge of TIOA TC_LDRA_FALLING_EDGE

1 1 Each edge of TIOA TC_LDRA_BOTH_EDGE

LDRB Edge

Code Label

TC_LDRB

00None TC_LDRB_EDGE_NONE

0 1 Rising edge of TIOA TC_LDRB_RISING_EDGE

1 0 Falling edge of TIOA TC_LDRB_FALLING_EDGE

1 1 Each edge of TIOA TC_LDRB_BOTH_EDGE

137

AT91X40 Series

1354D–ATARM–08/02

TC Channel Mode Register: Waveform Mode

Access Type: Read/Write

Reset Value:0

Offset: 0x04

• TCCLKS: Clock Selection

• CLKI: Clock Invert (Code Label TC_CLKI)

0 = Counter is incremented on rising edge of the clock.

1 = Counter is incremented on falling edge of the clock.

• BURST: Burst Signal Selection

• CPCSTOP: Counter Clock Stopped with RC Compare (Code Label TC_CPCSTOP)

0 = Counter clock is not stopped when counter reaches RC.

1 = Counter clock is stopped when counter reaches RC.

31 30 29 28 27 26 25 24

BSWTRG BEEVT BCPC BCPB

23 22 21 20 19 18 17 16

ASWTRG AEEVT ACPC ACPA

15 14 13 12 11 10 9 8

WAVE = 1 CPCTRG –ENETRG EEVT EEVTEDG

76543210

CPCDIS CPCSTOP BURST CLKI TCCLKS

TCCLKS Clock Selected

Code Label

TC_CLKS

000MCK/2 TC_CLKS_MCK2

001MCK/8 TC_CLKS_MCK8

010MCK/32 TC_CLKS_MCK32

0 1 1 MCK/128 TC_CLKS_MCK128

1 0 0 MCK/1024 TC_CLKS_MCK1024

101XC0 TC_CLKS_XC0

110XC1 TC_CLKS_XC1

111XC2 TC_CLKS_XC2

BURST Selected BURST

Code Label

TC_BURST

0 0 The clock is not gated by an external signal. TC_BURST_NONE

0 1 XC0 is ANDed with the selected clock. TC_BURST_XC0

1 0 XC1 is ANDed with the selected clock. TC_BURST_XC1

1 1 XC2 is ANDed with the selected clock. TC_BURST_XC2

138 AT91X40 Series

1354D–ATARM–08/02

• CPCDIS: Counter Clock Disable with RC Compare (Code Label TC_CPCDIS)

0 = Counter clock is not disabled when counter reaches RC.

1 = Counter clock is disabled when counter reaches RC.

• EEVTEDG: External Event Edge Selection

• EEVT: External Event Selection

Note: If TIOB is chosen as the external event signal, it is configured as an input and no longer generates waveforms.

• ENETRG: External Event Trigger Enable (Code Label TC_ENETRG)

0 = The external event has no effect on the counter and its clock. In this case, the selected external event only controls the

TIOA output.

1 = The external event resets the counter and starts the counter clock.

• CPCTRG: RC Compare Trigger Enable (Code Label TC_CPCTRG)

0 = RC Compare has no effect on the counter and its clock.

1 = RC Compare resets the counter and starts the counter clock.

• WAVE = 1 (Code Label TC_WAVE)

0 = Waveform Mode is disabled (Capture Mode is enabled).

1 = Waveform Mode is enabled.

• ACPA: RA Compare Effect on TIOA

EEVTEDG Edge

Code Label

TC_EEVTEDG

00None TC_EEVTEDG_EDGE_NONE

0 1 Rising edge TC_EEVTEDG_RISING_EDGE

1 0 Falling edge TC_EEVTEDG_FALLING_EDGE

1 1 Each edge TC_EEVTEDG_BOTH_EDGE

EEVT

Signal Selected as

External Event TIOB Direction

Code Label

TC_EEVT

0 0 TIOB Input(1) TC_EEVT_TIOB

0 1 XC0 Output TC_EEVT_XC0

1 0 XC1 Output TC_EEVT_XC1

1 1 XC2 Output TC_EEVT_XC2

ACPA Effect

Code Label

TC_ACPA

0 0 None TC_ACPA_OUTPUT_NONE

01Set TC_ACPA_SET_OUTPUT

10Clear TC_ACPA_CLEAR_OUTPUT

11Toggle TC_ACPA_TOGGLE_OUTPUT

139

AT91X40 Series

1354D–ATARM–08/02

• ACPC: RC Compare Effect on TIOA

• AEEVT: External Event Effect on TIOA

• ASWTRG: Software Trigger Effect on TIOA

• BCPB: RB Compare Effect on TIOB

• BCPC: RC Compare Effect on TIOB

ACPC Effect

Code Label

TC_ACPC

00None TC_ACPC_OUTPUT_NONE

01Set TC_ACPC_SET_OUTPUT

10Clear TC_ACPC_CLEAR_OUTPUT

1 1 Toggle TC_ACPC_TOGGLE_OUTPUT

AEEVT Effect

Code Label

TC_AEEVT

00None TC_AEEVT_OUTPUT_NONE

01Set TC_AEEVT_SET_OUTPUT

10Clear TC_AEEVT_CLEAR_OUTPUT

1 1 Toggle TC_AEEVT_TOGGLE_OUTPUT

ASWTRG Effect

Code Label

TC_ASWTRG

00None TC_ASWTRG_OUTPUT_NONE

01Set TC_ASWTRG_SET_OUTPUT

10Clear TC_ASWTRG_CLEAR_OUTPUT

11Toggle TC_ASWTRG_TOGGLE_OUTPUT

BCPB Effect

Code Label

TC_BCPB

00None TC_BCPB_OUTPUT_NONE

01Set TC_BCPB_SET_OUTPUT

1 0 Clear TC_BCPB_CLEAR_OUTPUT

1 1 Toggle TC_BCPB_TOGGLE_OUTPUT

BCPC Effect

Code Label

TC_BCPC

00None TC_BCPC_OUTPUT_NONE

01Set TC_BCPC_SET_OUTPUT

10Clear TC_BCPC_CLEAR_OUTPUT

1 1 Toggle TC_BCPC_TOGGLE_OUTPUT

140 AT91X40 Series

1354D–ATARM–08/02

• BEEVT: External Event Effect on TIOB

• BSWTRG: Software Trigger Effect on TIOB

BEEVT Effect

Code Label

TC_BEEVT

0 0 None TC_BEEVT_OUTPUT_NONE

01Set TC_BEEVT_SET_OUTPUT

10Clear TC_BEEVT_CLEAR_OUTPUT

11Toggle TC_BEEVT_TOGGLE_OUTPUT

BSWTRG Effect

Code Label

TC_BSWTRG

0 0 None TC_BSWTRG_OUTPUT_NONE

01Set TC_BSWTRG_SET_OUTPUT

10Clear TC_BSWTRG_CLEAR_OUTPUT

11Toggle TC_BSWTRG_TOGGLE_OUTPUT

141

AT91X40 Series

1354D–ATARM–08/02

TC Counter Value Register

Access Type: Read Only

Reset Value:0

Offset: 0x10

• CV: Counter Value (Code Label TC_CV)

CV contains the counter value in real-time.

TC Register A

Access Type: Read Only if WAVE = 0, Read/Write if WAVE = 1

Reset Value:0

Offset: 0x14

• RA: Register A (Code Label TC_RA)

RA contains the Register A value in real-time.

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76543210

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76543210

142 AT91X40 Series

1354D–ATARM–08/02

TC Register B

Access Type: Read Only if WAVE = 0, Read/Write if WAVE = 1

Reset Value:0

Offset: 0x18

• RB: Register B (Code Label TC_RB)

RB contains the Register B value in real-time.

TC Register C

Access Type: Read/Write

Reset Value:0

Offset:0x1C

• RC: Register C (Code Label TC_RC)

RC contains the Register C value in real-time.

31 30 29 28 27 26 25 24

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23 22 21 20 19 18 17 16

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15 14 13 12 11 10 9 8

76543210

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76543210

143

AT91X40 Series

1354D–ATARM–08/02

TC Status Register

Access Type: Read Only

Reset Value:0

Offset: 0x20

• COVFS: Counter Overflow Status (Code Label TC_COVFS)

0 = No counter overflow has occurred since the last read of the Status Register.

1 = A counter overflow has occurred since the last read of the Status Register.

• LOVRS: Load Overrun Status (Code Label TC_LOVRS)

0 = Load overrun has not occurred since the last read of the Status Register or WAVE = 1.

1 = RA or RB have been loaded at least twice without any read of the corresponding register since the last read of the Sta-

tus Register, if WAVE = 0.

• CPAS: RA Compare Status (Code Label TC_CPAS)

0 = RA Compare has not occurred since the last read of the Status Register or WAVE = 0.

1 = RA Compare has occurred since the last read of the Status Register, if WAVE = 1.

• CPBS: RB Compare Status (Code Label TC_CPBS)

0 = RB Compare has not occurred since the last read of the Status Register or WAVE = 0.

1 = RB Compare has occurred since the last read of the Status Register, if WAVE = 1.

• CPCS: RC Compare Status (Code Label TC_CPCS)

0 = RC Compare has not occurred since the last read of the Status Register.

1 = RC Compare has occurred since the last read of the Status Register.

• LDRAS: RA Loading Status (Code Label TC_LDRAS)

0 = RA Load has not occurred since the last read of the Status Register or WAVE = 1.

1 = RA Load has occurred since the last read of the Status Register, if WAVE = 0.

• LDRBS: RB Loading Status (Code Label TC_LDRBS)

0 = RB Load has not occurred since the last read of the Status Register or WAVE = 1.

1 = RB Load has occurred since the last read of the Status Register, if WAVE = 0.

• ETRGS: External Trigger Status (Code Label TC_ETRGS)

0 = External trigger has not occurred since the last read of the Status Register.

1 = External trigger has occurred since the last read of the Status Register.

• CLKSTA: Clock Enabling Status (Code Label TC_CLKSTA)

0 = Clock is disabled.

1 = Clock is enabled.

31 30 29 28 27 26 25 24

––––––––

23 22 21 20 19 18 17 16

–––––

MTIOB MTIOA CLKSTA

15 14 13 12 11 10 9 8

––––––––

76543210

ETRGS LDRBS LDRAS CPCS CPBS CPAS LOVRS COVFS

144 AT91X40 Series

1354D–ATARM–08/02

• MTIOA: TIOA Mirror (Code Label TC_MTIOA)

0 = TIOA is low. If WAVE = 0, this means that TIOA pin is low. If WAVE = 1, this means that TIOA is driven low.

1 = TIOA is high. If WAVE = 0, this means that TIOA pin is high. If WAVE = 1, this means that TIOA is driven high.

• MTIOB: TIOB Mirror (Code Label TC_MTIOB)

0 = TIOB is low. If WAVE = 0, this means that TIOB pin is low. If WAVE = 1, this means that TIOB is driven low.

1 = TIOB is high. If WAVE = 0, this means that TIOB pin is high. If WAVE = 1, this means that TIOB is driven high.

145

AT91X40 Series

1354D–ATARM–08/02

TC Interrupt Enable Register

Access Type: Write only

Offset: 0x24

• COVFS: Counter Overflow (Code Label TC_COVFS)

0 = No effect.

1 = Enables the Counter Overflow Interrupt.

• LOVRS: Load Overrun (Code Label TC_LOVRS)

0 = No effect.

1: Enables the Load Overrun Interrupt.

• CPAS: RA Compare (Code Label TC_CPAS)

0 = No effect.

1 = Enables the RA Compare Interrupt.

• CPBS: RB Compare (Code Label TC_CPBS)

0 = No effect.

1 = Enables the RB Compare Interrupt.

• CPCS: RC Compare (Code Label TC_CPCS)

0 = No effect.

1 = Enables the RC Compare Interrupt.

• LDRAS: RA Loading (Code Label TC_LDRAS)

0 = No effect.

1 = Enables the RA Load Interrupt.

• LDRBS: RB Loading (Code Label TC_LDRBS)

0 = No effect.

1 = Enables the RB Load Interrupt.

• ETRGS: External Trigger (Code Label TC_ETRGS)

0 = No effect.

1 = Enables the External Trigger Interrupt.

31 30 29 28 27 26 25 24

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23 22 21 20 19 18 17 16

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15 14 13 12 11 10 9 8

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76543210

ETRGS LDRBS LDRAS CPCS CPBS CPAS LOVRS COVFS

146 AT91X40 Series

1354D–ATARM–08/02

TC Interrupt Disable Register

Access Type: Write only

Offset:0x28

• COVFS: Counter Overflow (Code Label TC_COVFS)

0 = No effect.

1 = Disables the Counter Overflow Interrupt.

• LOVRS: Load Overrun (Code Label TC_LOVRS)

0 = No effect.

1 = Disables the Load Overrun Interrupt (if WAVE = 0).

• CPAS: RA Compare (Code Label TC_CPAS)

0 = No effect.

1 = Disables the RA Compare Interrupt (if WAVE = 1).

• CPBS: RB Compare (Code Label TC_CPBS)

0 = No effect.

1 = Disables the RB Compare Interrupt (if WAVE = 1).

• CPCS: RC Compare (Code Label TC_CPCS)

0 = No effect.

1 = Disables the RC Compare Interrupt.

• LDRAS: RA Loading (Code Label TC_LDRAS)

0 = No effect.

1 = Disables the RA Load Interrupt (if WAVE = 0).

• LDRBS: RB Loading (Code Label TC_LDRBS)

0 = No effect.

1 = Disables the RB Load Interrupt (if WAVE = 0).

• ETRGS: External Trigger (Code Label TC_ETRGS)

0 = No effect.

1 = Disables the External Trigger Interrupt.

31 30 29 28 27 26 25 24

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76543210

ETRGS LDRBS LDRAS CPCS CPBS CPAS LOVRS COVFS

147

AT91X40 Series

1354D–ATARM–08/02

TC Interrupt Mask Register

Access Type: Read Only

Reset Value:0

Offset:0x2C

• COVFS: Counter Overflow (Code Label TC_COVFS)

0 = The Counter Overflow Interrupt is disabled.

1 = The Counter Overflow Interrupt is enabled.

• LOVRS: Load Overrun (Code Label TC_LOVRS)

0 = The Load Overrun Interrupt is disabled.

1 = The Load Overrun Interrupt is enabled.

• CPAS: RA Compare (Code Label TC_CPAS)

0 = The RA Compare Interrupt is disabled.

1 = The RA Compare Interrupt is enabled.

• CPBS: RB Compare (Code Label TC_CPBS)

0 = The RB Compare Interrupt is disabled.

1 = The RB Compare Interrupt is enabled.

• CPCS: RC Compare (Code Label TC_CPCS)

0 = The RC Compare Interrupt is disabled.

1 = The RC Compare Interrupt is enabled.

• LDRAS: RA Loading (Code Label TC_LDRAS)

0 = The Load RA Interrupt is disabled.

1 = The Load RA Interrupt is enabled.

• LDRBS: RB Loading (Code Label TC_LDRBS)

0 = The Load RB Interrupt is disabled.

1 = The Load RB Interrupt is enabled.

• ETRGS: External Trigger (Code Label TC_ETRGS)

0 = The External Trigger Interrupt is disabled.

1 = The External Trigger Interrupt is enabled.

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76543210

ETRGS LDRBS LDRAS CPCS CPBS CPAS LOVRS COVFS

148 AT91X40 Series

1354D–ATARM–08/02

 i
 AT91X40 Series 
1354D–ATARM–08/02
Table of Contents
Features.................................................................................................  1
Description ............................................................................................  1
Pin Configuration..................................................................................  2
Block Diagram.......................................................................................  4
Architectural Overview.........................................................................  5
Memories .............................................................................................................. 5
Peripherals............................................................................................................ 5
Associated Documentation .................................................................  7
Product Overview .................................................................................  8
Power Supply........................................................................................................ 8
Input/Output Considerations ................................................................................. 8
Master Clock......................................................................................................... 8
Reset .................................................................................................................... 8
Emulation Function ............................................................................................... 8
Memory Controller ................................................................................................ 9
External Bus Interface ........................................................................................ 11
Peripherals ..........................................................................................  11
System Peripherals............................................................................................. 12
User Peripherals ................................................................................................. 14
Memory Map........................................................................................  15
Peripheral Memory Map .....................................................................  17
EBI: External Bus Interface................................................................  18
External Memory Mapping.................................................................................. 18
External Bus Interface Pin Description  .............................................................. 20
Chip Select Lines................................................................................................ 21
Data Bus Width................................................................................................... 23
Byte Write or Byte Select Access ....................................................................... 24
Boot on NCS0..................................................................................................... 26
Read Protocols ................................................................................................... 27
Write Data Hold Time ......................................................................................... 28
Wait States ......................................................................................................... 29
Memory Access Waveforms ............................................................................... 33
EBI User Interface .............................................................................................. 45
EBI Chip Select Register .................................................................................... 46
EBI Remap Control Register .............................................................................. 48
EBI Memory Control Register ............................................................................. 49

 ii AT91X40 Series  
1354D–ATARM–08/02
PS: Power-saving ...............................................................................  50
Peripheral Clocks................................................................................................ 50
PS User Interface ............................................................................................... 51
PS Control Register ............................................................................................ 52
PS Peripheral Clock Enable Register ................................................................. 53
PS Peripheral Clock Disable Register ................................................................ 54
PS Peripheral Clock Status Register .................................................................. 55
AIC: Advanced Interrupt Controller ..................................................  56
Hardware Interrupt Vectoring.............................................................................. 58
Priority Controller ................................................................................................ 58
Interrupt Handling ............................................................................................... 58
Interrupt Masking ................................................................................................ 58
Interrupt Clearing and Setting............................................................................. 59
Fast Interrupt Request ........................................................................................ 59
Software Interrupt ............................................................................................... 59
Spurious Interrupt ............................................................................................... 59
Protect Mode ...................................................................................................... 60
AIC User Interface .............................................................................................. 61
AIC Source Mode Register ................................................................................. 62
AIC Source Vector Register................................................................................ 63
AIC Interrupt Vector Register.............................................................................. 64
AIC FIQ Vector Register ..................................................................................... 64
AIC Interrupt Status Register.............................................................................. 65
AIC Interrupt Pending Register ........................................................................... 65
AIC Interrupt Mask Register ............................................................................... 66
AIC Core Interrupt Status Register ..................................................................... 67
AIC Interrupt Enable Command Register ........................................................... 68
AIC Interrupt Disable Command Register .......................................................... 68
AIC Interrupt Clear Command Register.............................................................. 69
AIC Interrupt Set Command Register ................................................................. 69
AIC End of Interrupt Command Register ............................................................ 70
AIC Spurious Vector Register............................................................................. 70
Standard Interrupt Sequence.............................................................................. 71
PIO: Parallel I/O Controller.................................................................  74
Multiplexed I/O Lines .......................................................................................... 74
Output Selection ................................................................................................. 74
I/O Levels............................................................................................................ 74
Filters .................................................................................................................. 74
Interrupts............................................................................................................. 75
User Interface ..................................................................................................... 75
PIO User Interface .............................................................................................. 78
PIO Enable Register ........................................................................................... 79
PIO Disable Register .......................................................................................... 79
PIO Status Register ............................................................................................ 80

 iii
 AT91X40 Series 
1354D–ATARM–08/02
PIO Output Enable Register ............................................................................... 81
PIO Output Disable Register .............................................................................. 81
PIO Output Status Register ................................................................................ 82
PIO Input Filter Enable Register ......................................................................... 83
PIO Input Filter Disable Register ........................................................................ 83
PIO Input Filter Status Register .......................................................................... 84
PIO Set Output Data Register ............................................................................ 85
PIO Clear Output Data Register ......................................................................... 85
PIO Output Data Status Register........................................................................ 86
PIO Pin Data Status Register ............................................................................. 86
PIO Interrupt Enable Register............................................................................. 87
PIO Interrupt Disable Register............................................................................ 87
PIO Interrupt Mask Register ............................................................................... 88
PIO Interrupt Status Register.............................................................................. 88
WD: Watchdog Timer .........................................................................  89
WD User Interface .............................................................................................. 90
WD Overflow Mode Register .............................................................................. 90
WD Clock Mode Register ................................................................................... 91
WD Control Register........................................................................................... 92
WD Status Register ............................................................................................ 92
WD Enabling Sequence...................................................................................... 93
SF: Special Function Registers.........................................................  94
Chip Identification ............................................................................................... 94
SF User Interface................................................................................................ 94
Chip ID Register ................................................................................................. 95
Chip ID Extension Register................................................................................. 96
Reset Status Register......................................................................................... 97
SF Memory Mode Register................................................................................. 98
SF Protect Mode Register .................................................................................. 98
USART: Universal Synchronous/Asynchronous  
Receiver/Transmitter ..........................................................................  99
Pin Description.................................................................................................... 99
Baud Rate Generator........................................................................................ 100
Receiver............................................................................................................ 101
Transmitter........................................................................................................ 103
Break ................................................................................................................ 104
Peripheral Data Controller ................................................................................ 105
Interrupt Generation.......................................................................................... 105
Channel Modes................................................................................................. 105
USART User Interface ...................................................................................... 107
USART Control Register................................................................................... 108
USART Mode Register ..................................................................................... 110
USART Interrupt Enable Register..................................................................... 112

 iv AT91X40 Series  
1354D–ATARM–08/02
USART Interrupt Disable Register.................................................................... 113
USART Interrupt Mask Register ....................................................................... 114
USART Channel Status Register...................................................................... 115
USART Receiver Holding Register................................................................... 117
USART Transmitter Holding Register............................................................... 117
USART Baud Rate Generator Register ............................................................ 118
USART Receiver Time-out Register................................................................. 119
USART Transmitter Time-guard Register......................................................... 119
USART Receive Pointer Register..................................................................... 120
USART Receive Counter Register ................................................................... 120
USART Transmit Pointer Register.................................................................... 121
USART Transmit Counter Register .................................................................. 121
TC: Timer Counter ............................................................................  122
Signal Name Description  ................................................................................. 123
Timer Counter Description................................................................................ 123
Capture Operating Mode .................................................................................. 126
Waveform Operating Mode............................................................................... 128
TC User Interface ............................................................................................. 131
TC Block Control Register ................................................................................ 132
TC Block Mode Register................................................................................... 133
TC Channel Control Register............................................................................ 134
TC Channel Mode Register: Capture Mode ..................................................... 135
TC Channel Mode Register: Waveform Mode.................................................. 137
TC Counter Value Register............................................................................... 141
TC Register A ................................................................................................... 141
TC Register B ................................................................................................... 142
TC Register C ................................................................................................... 142
TC Status Register ........................................................................................... 143
TC Interrupt Enable Register ............................................................................ 145
TC Interrupt Disable Register ........................................................................... 146
TC Interrupt Mask Register............................................................................... 147
Table of Contents ..................................................................................  i

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