MX809J - CML Microcircuits

DATA BULLETIN

MX809 1200bps MSK Modem

1998 MX-COM, Inc. www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054 Doc. # 20480036.004

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

PRELIMINARY INFORMATION

Features

 Half-Duplex 1200bps MSK Modem

operating under C-BUS control

 Software Selectable Checksum

Generation and Error Checking in

accordance with MPT1327

 Low Power Operation

 Member of DBS800 Family (C-BUS

Compatible)

ää

MSK

RECEIVER

CLOCK

GENERATOR

CHECKSUM

GEN/CHECK

BYTE COUNTER

SYNC/

DETECT

SYNC

DATA REGISTER 1 DATA REGISTER 2 MSK

TRANSMITTER

UNCOMMITTED

AMPLIFIER

INTERRUPT

GENERATOR IRQ

AMP OUT

AMP IN

STATUS

C-BUS

INTERFACE

AND

CONTROL

LOGIC

RX DATA BUFFER TX DATA BUFFER

8-BIT PARALLEL BUS

TX OUT

BIAS

RECOVERED

CLOCK

RX IN

XTAL/

CLOCK

XTAL

RX FREEFORMAT

DATA

SERIAL

CLOCK

COMMAND

DATA

WAKE CONTROL

ADDRESS

DECODER

ADDRESS

SELECT

SYNC PROGRAM

LOW - HIGH

INTERRUPT

ENABLE

RX DATA

READY

DETECT

SYNC

DETECT

SYNC RX SYNC

DETECT

RX SYNC

DETECT

TX DATA

READY TX IDLE

RECOVERED

CLOCK

The MX809 is an intelligent, half-duplex 1200-baud MSK Modem, which operates under C-BUS control. This

modem provides software selectable checksum generation and error checking in accordance with MPT1327.

In TX Mode the MX809 will:

1. a) Accept from the host and transmit 8-bit bytes of data as instructed (preamble, sync, address, and data), or

b) Internally calculate and inset a 2 byte checksum based on the preceding 6 bytes f data, or

c) Disable the internal checksum generator and continuously transmit the data supplied.

2. Transmit 1 hang-bit and go to TX idle when all loaded data bytes have been transmitted.

In RX Mode the MX809 will:

1. Detect and carry out bit synchronization within 16 bits.

2. a) Search and detect the user-programmed Sync (or its opposite logic sense) Word and carry out frame

synchronization. Data will then be output in 8-bit bytes via the RX Data Buffer.

b) Use the received checksum to calculate the presence of any errors, setting the Status Register accordingly.

3. Make the incoming data directly available via the RX Data Buffer (RX Freeformat), overriding the synchronization

requirements.

RX input timing is achieved by recovering an RX clock from the incoming data stream. Output tones are

timed to the internally generated TX clock. Filter, register clocks, and transmit MSK tone frequencies are

derived internally from the external Xtal or clock pulse input.

A 4.032MHz Xtal or clock input is required for compliance with the MPT1327 Signaling Specification. Note:

All information contained in this data bulletin is specified using a 4.032MHz Xtal, 1200bps baud rate, with

Mark and Space frequencies of 1200Hz and 1800Hz. The MX809 has a non-committed amplifier on-chip for

general applications in the DBS 800 series.

The MX809 may be used with a 5.0V power supply and is available in the following packages:

24-pin PLCC (MX809LH), and 24-pin CERDIP (MX809J).

MSK Modem 2 MX809

1998 MX-COM, Inc. www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054 Doc. # 20480036.004

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

Contents

Section Page

1 Block Diagram................................................................................................................3

2 Signal List.......................................................................................................................4

3 External Components....................................................................................................6

4 General Description.......................................................................................................7

5 Controlling Protocol......................................................................................................7

5.1 Address/Commands............................................................................................................ 7

5.2 Address Select .................................................................................................................... 8

5.3 Write to Control Register..................................................................................................... 9

5.4 RX Data buffer -- “Read RX Data Buffer” ............................................................................ 9

5.5 TX Data Buffer -- “Write to TX Data Buffer”....................................................................... 10

5.6 SYNC Program -- “Write to SYNC Program”..................................................................... 10

5.7 Read Status Register ........................................................................................................ 10

5.8 Interrupt Request............................................................................................................... 11

5.9 General Reset ................................................................................................................... 11

6 Application ...................................................................................................................12

6.1 Checksum Generation and Checking................................................................................ 12

6.1.1 Generation..............................................................................................................................12

6.1.2 Checking.................................................................................................................................12

6.2 Modem Performance......................................................................................................... 12

6.3 Modem Timing Information................................................................................................ 13

6.4 TX Timing.......................................................................................................................... 14

6.4.1 TX More Than One Message, SYNC Before Every Message, TX Checksum Enabled .........14

6.4.2 TX More Than One Message, TX Checksum Not Enabled. ...................................................14

6.4.3 TX One Message, TX Checksum Enabled .............................................................................15

6.4.4 TX One Message, TX Checksum Not Enabled.......................................................................15

6.5 RX Timing.......................................................................................................................... 16

6.5.1 RX SYNCSYNC/ Required Before Every Message, Rx Checksum Not Enabled .................16

6.5.2 RX Additional Data Follows Initial Address (6 Data & 2 Checksum Bytes) Data, RX checksum

Enabled...................................................................................................................................16

7 Performance Specifications........................................................................................17

7.1 Electrical Specifications..................................................................................................... 17

7.1.1 Absolute Maximum Limits.......................................................................................................17

7.1.2 Operating Limits......................................................................................................................17

7.1.3 Operating Characteristics .......................................................................................................18

7.1.4 Timing.....................................................................................................................................20

7.2 Packages........................................................................................................................... 21

MXCOM, Inc. reserves the right to change specifications at any time without notice.

MSK Modem 3 MX809

1998 MX-COM, Inc. www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054 Doc. # 20480036.004

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

1 Block Diagram

ää

MSK

RECEIVER

CLOCK

GENERATOR

CHECKSUM

GEN/CHECK

BYTE COUNTER

SYNC/

DETECT

SYNC

DATA REGISTER 1 DATA REGISTER 2 MSK

TRANSMITTER

UNCOMMITTED

AMPLIFIER

INTERRUPT

GENERATOR IRQ

AMP OUT

AMP IN

STATUS

C-BUS

INTERFACE

AND

CONTROL

LOGIC

RX DATA BUFFER TX DATA BUFFER

8-BIT PARALLEL BUS

TX OUT

BIAS

RECOVERED

CLOCK

RX IN

XTAL/

CLOCK

XTAL

RX FREEFORMAT

DATA

SERIAL

CLOCK

COMMAND

DATA

WAKE CONTROL

ADDRESS

DECODER

ADDRESS

SELECT

SYNC PROGRAM

LOW - HIGH

INTERRUPT

ENABLE

RX DATA

READY

DETECT

SYNC

DETECT

SYNC RX SYNC

DETECT

RX SYNC

DETECT

TX DATA

READY TX IDLE

RECOVERED

CLOCK

Figure 1: Block Diagram

MSK Modem 4 MX809

1998 MX-COM, Inc. www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054 Doc. # 20480036.004

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

2 Signal List

Pin Signal Description

1Xtal This is the output of the on-chip clock oscillator. External components are

required at this output when a Xtal is used. See Figure 2. Inset

2 Xtal/Clock This is the input to the on-chip clock oscillator inverter. A Xtal or externally

derived clock should be connected here. See Figure 2. Inset

3IRQ The output of this pin indicates an interrupt condition to the microcontroller by

going to a logic “0”. This is a “wire-or-able” output that enables the connection of

up to 8 peripherals to 1 interrupt port on the microcontroller. This pin is an open-

drain output, and therefore has a low impedance pulldown to logic “0” when active

and a high impedance when inactive. The conditions that cause interrupts are

indicted in the Status Register and are shown in Table 2. The system IRQ line

requires a pull-up resistor to VDD.

4 N/C

5 N/C

6Freeformat RX When this input is logic “0” in the RX Mode, it allows received data to be read

from the RX Data Buffer via the Reply Data line without having to achieve byte

synchronization (SYNC/SYNC) first. Data will continue to be available after this

input goes to a logic “1” until either a SYNC or SYNCPrime Bit is set or the

modem is set to TX Mode. When held at a logic “1” the modem operates

normally. This pin has an internal 1M pull-up resistor.

Note: If this input is held at a logic “0” in the TX Mode, the RX Data Ready bit in

the Status Register may occasionally be set, but not cause an interrupt. If this

input is a logic “0” when going into the RX Mode, and RX Data Ready interrupt

may be generated immediately (in this case the first byte of RX data should be

ignored).

BIAS The internal circuitry bias line, this is held at VDD/2. This pin must be decoupled

to VSS by capacitor C3. See Figure 2.

8 Amp In The inverting input to the on-chip uncommitted amplifier.

9 Amp Out The output of the on-chip uncommitted amplifier.

10 RX In This is the 1200 baud, 1200Hz/1800Hz received MSK signal input. The input

signal to this pin must be AC coupled via capacitor C4. See Figure 2.

11 N/C

12 VSS Negative Supply (GND)

13 TX Out This is the 1200 baud, 1200Hz/1800Hz MSK TX output. When not transmitting

data the output impedance of this pin is high. On power-up this output can be any

level. A General Reset command is required to ensure that this output attains

VBIAS initially.

14 N/C

15 N/C

16 N/C

17 Reply Data This is the C-BUS serial data output to the microcontroller. The transmission of

Reply Data bytes is synchronized to the Serial Clock under the CSinput. This 3-

state output is held high impedance when not sending data to the microcontroller.

See Section 6 and Section 7.1.4.

18 N/C

19 CS Select Chip . This is the ‘C-BUS’ data loading control function. This input is

provided by the microcontroller. Data transfer sequences are initiated, completed

or aborted by the CS signal. See Section 6 and Section 7.1.4.

20 Command Data This is the ‘C-BUS’ serial data input from the microcontroller. Data is loaded to

this device in 8-bit bytes, MSB (bit 7) first and LSB (bit 0) last, synchronized to the

Serial Clock. See Section 6 and Section 7.1.4.

MSK Modem 5 MX809

1998 MX-COM, Inc. www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054 Doc. # 20480036.004

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

Pin Signal Description

21 Serial Clock This is the ‘C-BUS’ serial Clock input. This clock, produced by the

microcontroller, is used for transfer timing of commands and data to and from the

MSK Modem. See Section 6 and Section 7.1.4.

22 Address Select This pin enables two MX809s to be used on the same C-BUS, providing full-

duplex operation. When at a logic “1” Address/Command bytes (with the

exception of a General Reset) must have bit 3 set to a logic “1” to address this

device. See Table 5 and Table 6.

23 Wake This input can be used to reactivate the MX809 from Powersave. The device will

be in Powersave when both this pin and bit 2 of the Control Register are set to

logic “1”. Recovery from Powersave is achieved by putting either the Wake pin or

the Powersave bit in the Control Register to logic “0”. This allows MX809

activation by the microcontroller or an external signal, such as R.S.S.I. or Carrier

Detect. See Table 3.

24 VDD Positive supply. A single +5.0V power supply is required. Levels and voltages

within the MSK Modem are dependent upon this supply.

Table 1: Signal List

TX Idle RX Data Ready TX Data Ready

RX SYNC Detect RX Sync Detect

Interrupt outputs can be disabled by bit 3 of the Control Register

Table 2: IRQ Conditions

Powersave (CR bit 2) Wake MX809 Condition

Powersave

Enabled

Table 3: Wake and Powersave Conditions

MSK Modem 6 MX809

1998 MX-COM, Inc. www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054 Doc. # 20480036.004

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

3 External Components

➤

SEE INSET

XTAL

XTAL/CLOCK

IRQ

RX FREEFORMAT

BIAS

AMP IN

AMP OUT

12 13

MX809J

RX IN

C4 V

WAKE

ADDRESS SELECT

SERIAL CLOCK

COMMAND DATA

REPLY D ATA

TX OUT

INSET

XTAL

C2 C1

X1 R1

XTAL/CLOCK

MX809J

Figure 2: Recommended External Components

Component Notes Value Tolerance

R1 1.0M±10%

R2 22.0K±10%

C1 1 33pF ±20%

C2 1 33pF ±20%

C3 1.0F±20%

C4 0.1F±20%

C5 1.0F±20%

X1 1 4.032MHz

Table 4: Recommended External Components

Recommended External Component Notes:

1. Xtal circuit capacitors C1 (CD) and C2 (CG) shown in Inset 2 are recommended in accordance with MX-

COM’s Crystal Oscillator Application Note.

MSK Modem 7 MX809

1998 MX-COM, Inc. www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054 Doc. # 20480036.004

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

4 General Description

The MX809 is an intelligent, half-duplex 1200-baud MSK Modem, which operates under C-BUS control. This

modem provides software selectable checksum generation and error checking in accordance with MPT1327.

In TX Mode the MX809 will:

1. a) Accept from the host and transmit 8-bit bytes of data as instructed (preamble, sync, address, and data), or

b) Internally calculate and inset a 2 byte checksum based on the preceding 6 bytes of data, or

c) Disable the internal checksum generator and continuously transmit the data supplied.

2. Transmit 1 hang-bit and go to TX idle when all loaded data bytes have been transmitted.

In RX Mode the MX809 will:

1. Detect and carry out bit synchronization within 16 bits.

2. a) Search and detect the user-programmed Sync (or its opposite logic sense) Word and carry out frame

synchronization. Data will then be output in 8-bit bytes via the RX Data Buffer.

b) Use the received checksum to calculate the presence of any errors, setting the Status Register accordingly.

3. Make the incoming data directly available via the RX Data Buffer (RX Freeformat), overriding the synchronization

requirements.

RX input timing is achieved by recovering an RX clock from the incoming data stream. Output tones are

timed to the internally generated TX clock. Filter, register clocks, and transmit MSK tone frequencies are

derived internally from the external Xtal or clock pulse input.

A 4.032MHz Xtal or clock input is required for compliance with the MPT1327 Signaling Specification. Note:

All information contained in this data bulletin is specified using a 4.032MHz Xtal, 1200bps baud rate, with

Mark and Space frequencies of 1200Hz and 1800Hz. The MX809 has a non-committed amplifier on-chip for

general applications in the DBS 800 series.

5 Controlling Protocol

Control of the functions within the MX809 MSK Modem is by a group of Address/Commands and appended

data instructions from the system microcontroller. Two separate MSK Modems can be addressed. The use

of these A/Cs is detailed in the following paragraphs and tables.

Command Assignment Address/Command

Binary Command Data

HEX MSB LSB

General Reset 01 00000001 Control Register bits set to logic “0”

Write to Control Register 40 01000000 + 1 byte instruction to Control Register

Read Status Register 41 01000001 + 1 byte reply from Status Register

Read RX Data Buffer 42 01000010 + 1 byte of data from RX Data Buffer

Write to TX Data Buffer 43 01000011 + 1 byte of data to TX Data Buffer

Write to SYNC Program 44 01000100 + 2 bytes of SYNC Word to SYNC

Program. Register

Table 5: Modem No. 1 C-BUS Address/Commands – (Address Select input at a logic “0”)

5.1 Address/Commands

Instructions and data transactions to and from the MX809 consist of an Address/Command (A/C) byte

followed by either further instructions or data, or a Status or RX Data Reply.

Control and configuration is by writing instructions from the microcontroller to the Control Register [40H (48H)].

Reporting of the MX809 configuration is by reading the Status Register [41H (49H)]. Instructions and data are

transferred via C-BUS in accordance with the timing information given in Figure 11.

Data to be transmitted as MSK is sent to the TX Data Buffer via the Command Data line. Received data is

read from the RX Data buffer via the Reply Data line.

Instructions and data transactions to and from this device are preceded by the relevant A/C.

MSK Modem 8 MX809

1998 MX-COM, Inc. www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054 Doc. # 20480036.004

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

C-BUS allocations for the MX809 are shown in Table 5 and Table 6.

Command Assignment Address/Command

Binary Command Data

HEX MSB LSB

General Reset 01 00000001 Control Register bits set to logic “0”

Write to Control Register 48 01001000 + 1 byte instruction to Control Register

Read Status Register 49 01001001 + 1 byte reply from Status Register

Read RX Data Buffer 4A 01001010 + 1 byte of data from RX Data Buffer

Write to TX Data Buffer 4B 01001011 + 1 byte of data to TX Data Buffer

Write to SYNC Program 4C 01001100 + 2 bytes of SYNC Word to SYNC

Program Register

Table 6: Modem No. 2 C-BUS Address/Commands – (Address Select input at a logic “1”)

5.2 Address Select

This input allows 2 MSK Modems on the same BUS, using the correct addressing.

When operating in a system using 2 MSK Modems, one MSK Modem is designated No. 1 and requires its

Address Select input to be held at a logic “0”. The second Modem (No. 2) requires its Address select input to

be held at logic “1”.

All C-BUS transactions with Modem 1 will use Address/Command allocations 40H to 44H (Table 5) and

transactions with Modem 2 will use 48H to 4CH (Table 6).

For explanation purposes, further descriptions of MX809 MSK Modem internal register functions will deal

primarily with MSK Modem No. 1 (Address Select at logic “0”).

MSK Modem 9 MX809

1998 MX-COM, Inc. www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054 Doc. # 20480036.004

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

5.3 Write to Control Register

This “Write Only” register directs the Modem’s operation.

SYNC: When set, this bit enables SYNCWord detection. It is cleared on a successful SYNC Word

detection.

SYNC Prime: When set, this bit enables SYNC Word detection. It is cleared on a successful SYNC Word

detection.

Interrupt Enable: When set, this bit allows interrupts to be output by the MX809 on the IRQ line.

Powersave: Used in conjunction with the Wake input (see Section 2) to control the Powersave state of the

MX809.

Checksum Enable: When set:

In TX: A 2-byte checksum is generated and transmitted after every 6 bytes transmitted.

In RX: After every 8 received bytes (6 information + 2 checksum) the checksum word is checked. If

the checksum is correct, the RX Checksum True bit in the Status Register is set to a logic “1”. When

this bit is a logic “0” no checksum are generated or checked.

Note: Checksum operation is inhibited during the SYNC/SYNC search period.

Setting Control bits

MSB Transmitter first

Bit 7 Not Used

Set to “0”

6Not Used

Set to “0”

5SYNC Prime

1 Primed

4 SYNC Prime

1 Primed

3 Interrupt Enable

1Disable

Enable

2 Powersave

1Normal Operation

Powersave

1 Checksum Enable

1Disable

Enable

0 RX/TX Mode

1RX

Table 7: Control Register

5.4 RX Data buffer -- “Read RX Data Buffer”

This “Read Only” register contains the last byte of data received from the Data Register. Data is received Bit

7 (MSB) first.

MSB LSB

7 654321 0

RX Data Buffer

MSK Modem 10 MX809

1998 MX-COM, Inc. www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054 Doc. # 20480036.004

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

5.5 TX Data Buffer -- “Write to TX Data Buffer”

This “Write Only” register contains the next byte of data to be transmitted. Bit 7 (MSB) is transmitted first.

MSB LSB

7 654321 0

TX Data Buffer

5.6 SYNC Program -- “Write to SYNC Program”

This “Write Only” register is loaded with the required SYNC word. This word (or its opposite logic sense,

SYNC) is compared with the received synchronization word. If the required SYNC Word is less that 16bits,

the remaining bits must be programmed as preamble (10101010…etc). Bit 15 (MSB) is loaded first.

MSB Byte 1 Byte 2 LSB

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

SYNC High SYNC Low

5.7 Read Status Register

This “Read Only” register indicated the source of MX809 interrupts ( sIRQ ).

RX SYNC Detect: This is set and an Interrupt is generated when the correct SYNCWord is detected (if

SYNCPrime is set).

It is cleared by (1) reading the Status Register, and (2) setting TX/RX to logic “1”.

RX SYNC Detect: This is set and an Interrupt is generated when the correct SYNC Word is detected (if

SYNC Prime is set).

It is cleared by (1) reading the Status Register, and (2) setting TX/RX to logic “1”.

TX Idle: This is set and an Interrupt is generated when all loaded TX data and 1 “hang-bit” have been

transmitted.

It is cleared by (1) writing to the TX Data Buffer, and (2) setting TX/RX to logic “0”.

TX Data Ready: This is set and an Interrupt generated indicating that a byte of data should be written to the

TX Data Buffer.

It is cleared by (1) reading the Status Register and writing a byte of data to the TX Data Buffer, and (2) setting

TX/RX to logic “0”.

RX Data Ready: When this is set and an Interrupt generated, it indicates that the RX Data Buffer is full, and

that a byte of data is to be read from the RX Data buffer. This must be read within 8 bit periods.

It is cleared by (1) reading the Status Register and the RX Data buffer, and (2) setting the TX/RX to logic “1”/

RX Checksum True: This is set and an Interrupt is generated by a successful comparison of the received

and self-generated checksums.

It is cleared by (1) reading the Status Register and the RX Data Buffer, and (2) TX/RX being taken to logic

“1”

MSK Modem 11 MX809

1998 MX-COM, Inc. www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054 Doc. # 20480036.004

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

Reading Status Bits

MSB Received First

Bit 7 Undefined

1“0” or

“1”

6 Undefined

1“0” or

“1”

5RX SYNC Detect

1SYNC

4 RX SYNC Detect

1SYNC

3 TX Idle

1Idle

2 TX Data Ready

1 TX Date Ready

1 RX Checksum True

1True

0 RX Data Ready

1 RX Data Ready

Table 8: Status Register

5.8 Interrupt Request

The conditions that cause interrupts to be output (if enabled by the Control Register) from the MX809 are:

TX Idle

TX Data Ready

RX SYNCDetect

RX Data Ready

RX SYNC Detect

The Status Register should be read to find the cause of the interrupt. Interrupts are cleared by (1) reading the

Status Register, or (2) changing the state of the TX/RX bit.

5.9 General Reset

Upon power-up, the bits in the MX809 Mode register and buffer will be random (either “0” or “1”). The

General Reset command (01H) will “reset” all microcircuits in the C-BUS and had the following effect on the

MX809.

All bits in the Control Register will be set to logic “0”. The Tx Out output will be set to VBIAS.

Note: The Status register, RX Data Buffer, TX Data Buffer, and SYNC Program register are not affected by

the General Reset Command.

MSK Modem 12 MX809

1998 MX-COM, Inc. www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054 Doc. # 20480036.004

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

6 Application

6.1 Checksum Generation and Checking

6.1.1 Generation

The checksum generator takes the 48 bits from the 6 bytes loaded into the TX Data Buffer and divides them

into modulo-2 by the generating polynomial:

x15 + x14 + x13 + x11 + x4 + x2 + x1

It then takes the 15-bit remainder from the polynomial divider, inverts the last bit and appends an EVEN parity

bit generated from the initial 48 bits and the 15 bit remainder (with the last bit inverted). This 16 bit word is

used as the “Checksum”.

6.1.2 Checking

The checksum checker does two things:

1. It takes the first 63 bits of a received message, inverts bit 63, and divides them modulo-2 by the

generating polynomial:

x15 + x14 + x13 + x11 + x4 + x2 + x1

2. The 15 bits remaining in the polynomial divider are checked to make sure that they are all zero.

3. It generates an even parity bit from the first 63 bits of a received message and compares this bit with the

received parity (bit 64).

If the 15 bits in the polynomial divider are all zero and the two parity bits are equal, then the RX

Checksum True (Status Register bit 1) is set.

6.2 Modem Performance

Figure 3: Bit Error Rate vs. Signal-to-Noise Ratio

MSK Modem 13 MX809

1998 MX-COM, Inc. www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054 Doc. # 20480036.004

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

6.3 Modem Timing Information

Figure 4: Modem Timing

Notes:

1. The SYNC and SYNCdetector searches the incoming bit stream starting at the end of the byte in which

SYNC/SYNC Prime was set.

2. After detection of a SYNC/SYNC word, the SYNC/SYNC Prime bits automatically go low (control bits 5

and 6: detector off.

3. The checksum checker is inhibited during the time SYNC/SYNC search is operating.

4. The Status Register will indicate whether SYNC or SYNC was detected here.

5. Any number of preamble bits can occur here.

6. Any number of bits can occur here.

7. Freeformat RX set high.

MSK Modem 14 MX809

1998 MX-COM, Inc. www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054 Doc. # 20480036.004

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

6.4 TX Timing

A – Address bytes

C – Checksum bytes

D – Data bytes

H – Hang bit

P – Preamble bytes

- Don’t care state

TX only – In TX, Preamble, and SYNC are

loaded as data from the microcontroller.

6.4.1 TX More Than One Message, SYNC Before Every Message, TX Checksum Enabled

NOTE 6

RX/TX

TX OUTPUT

IRQ

READ STATUS

TX DATA READY

WRITE TO

TX DATA BUFFER

CHECKSUM

ON/OFF

P1 P2 P

S1 S2 A1 A2 A3 A4 A5 A6 C1 C2 S1 S2 D1 D2 D3 D4 D5 D6

S1 S2 A1 A2 A3 A4 A5 A6 S2

S1 D1 D2 D3 D4 D5 D6

Figure 5: TX More Than One Message, SYNC Before Every Message, TX Checksum Enabled

Notes:

1. Preamble and SYNC bytes are loaded as data from the microcontroller.

2. The TX output will be held at bias level when no data is being transmitted.

3. TX byte synchronization is established by loading of the first preamble byte from the microcontroller.

4. Checksum must be turned off during preamble and SYNC words.

5. When TX/RX is low, TX output is at bias.

6. Any number of preamble bytes can occur here.

6.4.2 TX More Than One Message, TX Checksum Not Enabled.

NOTE 2 NOTE 3 NOTE 3

RX/TX

TX OUTPUT

IRQ

READ STATUS

TX DATA READY

WRITE TO

TX DATA BUFFER

CHECKSUM

ON/OFF

P1 P2 P

S1 S2 A1 A2 A3 A4 A S1 S2 D1 D2 D3 D4 D S1 S2 D1

S1 S2 A1 A2 A3 A4 A S1 S2 D1 D2 D3 D S1 S2 D1 D2

Figure 6: TX More Than One Message, TX Checksum Not Enabled.

Notes:

1. Preamble, SYNC words and checksums are supplied by the microcontroller in this format as data bytes.

2. Any number of preamble bytes can occur here.

3. Any number of address/data bytes can occur here.

MSK Modem 15 MX809

1998 MX-COM, Inc. www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054 Doc. # 20480036.004

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

6.4.3 TX One Message, TX Checksum Enabled

NOTE 2

RX/TX

TX OUTPUT

IRQ

READ STATUS

TX DATA READY

WRITE TO

TX DATA BUFFER

CHECKSUM

ON/OFF

TX IDLE

P2 P

S2 A1 A2 A3 A4 A5 A6 C1 C2 H

PP2

A6A5A4A3A2A1

Figure 7: TX One Message, TX Checksum Enabled

Notes:

1. H is the “Hangover bit” (Logic1) appended to the transmitted message before transmission is terminated.

2. Any number of preamble bytes can occur here.

3. Transmission terminates after C1, C2, and H. Termination occurs when no further data bytes are written

to the TX Data Buffer.

6.4.4 TX One Message, TX Checksum Not Enabled.

NOTE 2

RX/TX

TX OUTPUT

IRQ

READ STATUS

TX DATA READY

WRITE TO

TX DATA BUFFER

CHECKSUM

ON/OFF

TX IDLE

NOTE 3

PP2 HAA5A4A3A2A1

A5A4A3A2

S2 A1

PP2

Figure 8: TX One Message, TX Checksum Not Enabled

Notes:

1. H is the “Hangover bit” (Logic1) appended to the transmitted message before transmission is terminated.

2. Any number of preamble bytes can occur here.

3. Any number of address/data bytes can occur here.

4. Transmission terminates when no further data bytes are loaded into the TX Data Buffer.

MSK Modem 16 MX809

1998 MX-COM, Inc. www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054 Doc. # 20480036.004

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

6.5 RX Timing

A – Address bytes

C – Checksum bytes

D – Data bytes

H – Hang bit

P – Preamble bytes

- Don’t care state

TX only – In TX, Preamble, and SYNC are

loaded as data from the microcontroller.

6.5.1 RX SYNCSYNC/Required Before Every Message, Rx Checksum Not Enabled

NOTE 1 NOTE 2 NOTE 3

P1 P2 P

A1 A2 A3

A1 A2 A3 A

SYNCSYNC

RX/TX

RX INPUT

IRQ

READ STATUS REGISTER

SYNC DETECT

(OR DETECT)SYNC

RX DATA READY

READ RX DATA BUFFER

SYNC/ PRIMESYNC

CHECKSUM ON/OFF

Figure 9: RX SYNCSYNC/ Required Before Every Message, RX Checksum not Enabled

Notes:

1. Any number of preamble bits can occur here.

2. Any number of address/data bytes can occur here.

3. Any number of bits can occur here

4. FreeformatRX set high.

6.5.2 RX Additional Data Follows Initial Address (6 Data & 2 Checksum Bytes) Data, RX checksum

Enabled

NOTE 1

SYNC

RX/TX

RX INPUT

IRQ

READ STATUS

RX DATA READY

SYNC DETECT

(OR

DETECT)

SYNC

READ RX

DATA BUFFER

RX CHECKSUM

TRUE

SYNC/

PRIMESYNC

CHECKSUM

ON/OFF

P1 P2 P

A1 A2 A3 A4 A5 A6 C1 C2 D1 D2 D3 D4 D5 D6 C1 C2 D1

Figure 10: RX Additional Data Follows Initial Address (6 Data & 2 Checksum Bytes) Data , RX

Checksum Enabled

Notes:

1. Any number of preamble bits can occur here.

2. FreeformatRX set high.

MSK Modem 17 MX809

1998 MX-COM, Inc. www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054 Doc. # 20480036.004

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

7 Performance Specifications

7.1 Electrical Specifications

7.1.1 Absolute Maximum Limits

Exceeding these maximum ratings can result in damage to the device.

General Notes Min. Typ. Max. Units

Supply (VDD-VSS) -0.3 7.0 V

Voltage on any pin to VSS -0.3 VDD + 0.3 V

Current

VDD -30 30 mA

VSS -30 30 mA

Any other pin -20 20 mA

J / LH Packages

Total allowable Power dissipation

at TAMB = 25C800 mW

Derating above 25C10 mW/C above 25C

Operating Temperature -40 85 C

Storage Temperature -55 125 C

Table 9: Absolute Maximum Ratings

7.1.2 Operating Limits

Correct Operation of the device outside these limits is not implied.

Notes Min. Typ. Max. Units

Supply (VDD-VSS) 4.5 5.0 5.5 V

Operating Temperature -40 85 C

Xtal Frequency 4.032 MHz

Table 10: Operating Limits

MSK Modem 18 MX809

1998 MX-COM, Inc. www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054 Doc. # 20480036.004

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

7.1.3 Operating Characteristics

For the following conditions unless otherwise specified.

VDD = 5.0V @ TAMB = 25C

Xtal/Clock Frequency = 4.032MHz, Audio Level 0dB ref. = 308mVRMS @ 1kHz

Bit Rate = 1200bps

Notes Min. Typ. Max. Units

Static Values

Supply Current

Enabled 5.0 mA

Powersave 2.0 mA

Dynamic Values

Digital Interface

Input Logic “1” 1 3.5 V

Input Logic “0” 1 1.5 V

Output Logic “1” (IOH = -120A) 2 4.6 V

Output Logic “0” (IOH = 360A) 2, 3 0.4 V

Digital Input Current

VIN = Logic “1” or “0” 1 1.0 A

Digital Input Capacitance 1 7.5 pF

Tri-State “OFF” Leakage Current 8 -4.0 4.0 A

Analog Impedance

Input Impedance 100 k

Output Impedance

Transmitting Data 6.0 10.0 k

Not Transmitting Data 1.0 k

On-Chip Xtal Oscillator

RIN 10.0 M

ROUT 5.0 k

Gain 15.0 dB

Frequency 4 4.032 MHz

Receiver

Signal Input Levels 5 -9.0 -2.0 10.5 dB

Bit Error Rate

At 12dB SNR 7.0 10-4

At 20dB SNR 1.0 10-8

Synchronization at 12dB SNR 6

Probability of Bit 8 being correct 99.0 %

Probability of Bit 16 being correct 99.5 %

MSK Modem 19 MX809

1998 MX-COM, Inc. www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054 Doc. # 20480036.004

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

Notes Min. Typ. Max. Units

Transmitter

Output Level 0 dB

Output Level Variation -1.0 1.0 dB

Output Distortion 3.0 5.0 %

Third Harmonic Distortion 2.0 3.0 %

Logic “1” Frequency 7 1200 Hz

Logic “0” Frequency 7 1800 Hz

Isochronous Distortion

1200Hz – 1800Hz 25.0 40.0 s

1800Hz – 1200Hz 20.0 40.0 s

Uncommitted Amplifier

Bandwidth 200 kHz

Gain 50.0 dB

Input Impedance 1.0

Output Impedance 10.0 k

Table 11: Operating Characteristics

Operating Characteristics Notes:

1. Device control pins: Serial Clock, Command Data, Wake , and CS.

2. Reply Data output.

3. IRQ output

4. For baud rate specified (1200 baud)

5. Signal-to-Noise Ratio = 50dB

6. The response time is measured using 10101010…101 signal input pattern at 230mVRMS (-2.5dB) with

noise.

7. Dependant upon Xtal tolerance.

8. IRQ and Reply Data outputs for VSS < VOUT < VDD.

MSK Modem 20 MX809

1998 MX-COM, Inc. www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054 Doc. # 20480036.004

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

7.1.4 Timing

C-BUS Timing Min. Typ. Max. Units

tCSE Chip Select Low to First Serial Clock Rising Edge 2.0 s

tCHS Last Serial Clock Rising Edge to Chip Select High 4.0 s

tHIZ Chip Select High to Reply Data High -Z 2.0

tCSOFF Chip Select High time between transactions 2.0 s

tNXT Inter-Byte Time 4.0 s

tCK Serial Clock Period 2.0 s

Table 12: Timing Information

Notes:

1. Depending on the command, 1 or 2 bytes of Command Data is transmitted to the peripheral MSB (bit 7)

first, LSB (bit 0) last. Reply Data is read from the peripheral MXB (bit 7) first, LSB (bit 0) last.

2. Data is clocked into and out of the peripheral on the rising Serial Clock edge.

3. Loaded commands are acted upon at the end of each command.

4. To allow for differing microcontroller serial interface formats, C-BUS compatible ICs are able to work with

either polarity Serial Clock pulses.

CHIP SELECT

SERIAL CLOCK

COMMAND DATA

REPLY DATA

ADDRESS/COMMAND

BYTE FIRST DATA BYTE LAST DATA BYTE

FIRST REPLY DATA BYTE LAST REPLY DATA BYTE

Logic level is not important

MSB LSB

76543210

MSB LSB

76543210

MSB LSB

76543210

MSB LSB MSB LSB

CSOFF

CSH

HIZ

NXT

CSE

Figure 11: C-BUS Timing Information

MSK Modem 21 MX809

1998 MX-COM, Inc. www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054 Doc. # 20480036.004

4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.

7.2 Packages

NOTE : All dimension s in inches (mm.)

Angles are in degrees

PackageTolerances

TYP. MAX.MIN.DIM.

0.220 (5.59)

0.555 (14.04)

0.670 (17.02)

7°

0.160 (4.05)

1.270 (32.26)

0.151 (3.84)

0.100 (2.54)

0.121 (3.07)

0.600 (15.24)

0.590 (14.99) 0.625 (15.88)

0.015 (0.38) 0.045 (1.14)

0.008 (0.20) 0.015 (0.38)

0.015 (0.38) 0.023 (0.58)

0.040 (1.02) 0.065 (1.65)

0.066 (1.67) 0.074 (1.88)

1.200 (30.48)

0.500 (12.70)

PIN1

PIN1 T

Figure 12: 24-pin CERDIP Mechanical Outline:

Order as part no. MX809J

PackageTolerances

NOTE : All dimension s in inches (mm.)

Angles are in degrees

TYP. MAX.MIN.DIM.

0.435 (11.05)

0.051 (1.30)

0.009 (0.22)

6°

30°

0.409 (10.40)

0.146 (3.70)

0.417 (10.60)

0.049 (1.24)

0.006 (0.152)

0.250 (6.35)

0.023 (0.58)

0.047 (1.19) 0.022 (0.55)0.018 (0.45)

0.380 (9.61)

0.128 (3.25)

0.048 (1.22)

45°

PIN 1

Figure 13: 24-pin PLCC Mechanical Outline:

Order as part no. MX809LH

CML Product Data

In the process of creating a more global image, the three standard product semiconductor

companies of CML Microsystems Plc (Consumer Microcircuits Limited (UK), MX-COM, Inc

(USA) and CML Microcircuits (Singapore) Pte Ltd) have undergone name changes and, whilst

maintaining their separate new names (CML Microcircuits (UK) Ltd, CML Microcircuits (USA)

Inc and CML Microcircuits (Singapore) Pte Ltd), now operate under the single title CML

Microcircuits.

These companies are all 100% owned operating companies of the CML Microsystems Plc

Group and these changes are purely changes of name and do not change any underlying legal

entities and hence will have no effect on any agreements or contacts currently in force.

CML Microcircuits Product Prefix Codes

Until the latter part of 1996, the differentiator between products manufactured and sold from

MXCOM, Inc. and Consumer Microcircuits Limited were denoted by the prefixes MX and FX

respectively. These products use the same silicon etc. and today still carry the same prefixes.

In the latter part of 1996, both companies adopted the common prefix: CMX.

This notification is relevant product information to which it is attached.

CML Microcircuits (USA) [formerly MX-COM, Inc.] Product Textual Marking

On CML Microcircuits (USA) products, the ‘MX-COM’ textual logo is being replaced by a ‘CML’

textual logo.

Company contact information is as below:

CML Microcircuits

(UK)Ltd

COMMUNICATION SEMICONDUCTORS

CML Microcircuits

COMMUNICATION SEMICONDUCTORS

CML Microcircuits

(Singapore)PteLtd

COMMUNICATION SEMICONDUCTORS

CML Microcircuits

(USA) Inc.

COMMUNICATION SEMICONDUCTORS

Oval Park, Langford, Maldon,

Essex, CM9 6WG, England

Tel: +44 (0)1621 875500

Fax: +44 (0)1621 875600

uk.sales@cmlmicro.com

www.cmlmicro.com

4800 Bethania Station Road,

Winston-Salem, NC 27105, USA

Tel: +1 336 744 5050,

0800 638 5577

Fax: +1 336 744 5054

us.sales@cmlmicro.com

www.cmlmicro.com

No 2 Kallang Pudding Road, 09-05/

06 Mactech Industrial Building,

Singapore 349307

Tel: +65 7450426

Fax: +65 7452917

sg.sales@cmlmicro.com

www.cmlmicro.com

D/CML (D)/2 May 2002