4-Level FSK Modem Data Pump

Page 2 of 50

MX929B PRELIMINARY INFORMATION

©2001 MX-COM, INC.

www.mxcom.com Tel: 800 638 5577 336 744 5050

Fax: 336 744 5054

Doc. # 20480171.003

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 ............................................................................................................... 6

2. Signal List...................................................................................................................... 7

3. External Components ................................................................................................... 8

4. General Description .................................................................................................... 10

4.1 Description of Blocks ....................................................................................................... 10

4.1.1

Data Bus Buffers................................................................................................................... 10

4.1.2

Address and R/W Decode .................................................................................................... 10

4.1.3

Status and Data Quality Registers ........................................................................................ 10

4.1.4

Command, Mode, and Control Registers ............................................................................. 10

4.1.5

Data Buffer............................................................................................................................ 10

4.1.6

CRC Generator/Checker ...................................................................................................... 10

4.1.7

FEC Generator/Checker ....................................................................................................... 10

4.1.8

Interleave/De-Interleave Buffer ............................................................................................. 10

4.1.9

Frame Sync Detect ...............................................................................................................10

4.1.10 Rx Input Amp ........................................................................................................................ 11

4.1.11 RRC Low Pass Filter.............................................................................................................11

4.1.12 Tx Output Buffer ................................................................................................................... 12

4.1.13 Rx Level/Clock Extraction ..................................................................................................... 13

4.1.14 Clock Oscillator and Dividers ................................................................................................ 13

4.2 Modem - µC Interaction ................................................................................................... 13

4.3 Binary to Symbol Translation ........................................................................................... 14

4.4 Frame Structure............................................................................................................... 15

4.5 The Programmer's View .................................................................................................. 16

4.5.1

Data Block Buffer .................................................................................................................. 16

4.5.2

Command Register............................................................................................................... 17

4.5.2.1

Command Register B7: AQSC - Acquire Symbol Clock ............................................ 17

4.5.2.2

Command Register B6: AQLEV - Acquire Receive Signal Levels ............................. 17

4.5.2.3

Command Register B5: CRC .................................................................................... 17

4.5.2.4

Command Register B4: TXIMP - Tx Level/Impulse Shape ........................................ 17

4.5.2.5

Command Register B3 - Reserved ............................................................................ 17

4.5.2.6

Command Register B2, B1, B0: TASK....................................................................... 18

4.5.2.7

NULL: No effect.......................................................................................................... 19

4.5.2.8

SFP: Search for Frame Preamble .............................................................................. 19

4.5.2.9

RHB: Read Header Block........................................................................................... 20

4.5.2.10

RILB: Read 'Intermediate' or 'Last' Block ................................................................... 20

4.5.2.11

SFS: Search for Frame Sync...................................................................................... 20

4.5.2.12

R4S: Read 4 Symbols ................................................................................................ 20

4.5.2.13

RSID: Read Station ID................................................................................................ 20

4.5.2.14

T24S: Transmit 24 Symbols ....................................................................................... 21

4.5.2.15

THB: Transmit Header Block...................................................................................... 21