MX COM Inc MX809J, MX809LH Datasheet

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

REPLY DATA

SERIAL CLOCK

COMMAND DATA

WAKE

CONTROL REGISTER

ADDRESS DECODER

ADDRESS

SELECT

SYNC PROGRAM

LOW - HIGH

INTERRUPT

ENABLE

RX DATA

READY

DETECT

SYNC

DETECT

SYNC

RX SYNC

DETECT

RX SYNC

DETECT

TX DAT A

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

GENERA T OR

CHECKSUM

GEN/CHECK

BYTE COUNTER

SYNC/

DETECT

SYNC

DATA REGISTER 1 DATA REGISTER 2

MSK

TRANSMITTER

UNCOMMITTED

AMPLIFIER

INTERRUPT

GENERA T OR

IRQ

AMP OUT

AMP IN

ST ATUS

C-BUS

INTERFACE

AND

CONTROL

LOGIC

RX DATA BUFFER TX DATA BUFFER

8-BIT PARALLEL BUS

TX OUT

BIAS

RECOVERED

CLOCK

RX IN

XT AL/ CLOCK

XT AL

RX FREEFORMA T

REPLY DAT A

SERIAL CLOCK

COMMAND DAT A

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

Xtal

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

IRQ

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 opendrain 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 V

. 4 N/C 5 N/C 6

Freeformat 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 V

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 V

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

BIAS

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

input. This 3state output is held high impedance when not sending data to the microcontroller. See Section 6 and Section 7.1.4.

18 N/C 19

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.

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 V

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

1 0 1 0

1 1 0 0

Powersave

Enabled Enabled 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

1 2 3 4 5 6 7 8 9

MX809J

RX IN

WAKE ADDRESS SELECT SERIAL CLOCK

COMMAND DA TA CS

REPLY DATA

TX OUT

INSET

XTAL

C2 C1

X1 R1

XTAL/CLOCK

MX809J

Figure 2: Recommended External Components

Component Notes Value Tolerance

1.0M



±10%

22.0K



±10%

C1 1 33pF ±20% C2 1 33pF ±20% C3

1.0F

±20%

0.1F

±20%

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 MXCOM’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

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.

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 [40

(48H)].

Reporting of the MX809 configuration is by reading the Status Register [41

(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.

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MX COM Inc MX809J, MX809LH Datasheet

Specifications and Main Features

Frequently Asked Questions

User Manual