AX.25 Modem
CMX7031/CMX7041
CONTENTS
Section
Page
1
Brief Description .................................................................................................. 1
1.1
3.1
History.............................................................................................................. 5
2
3
Block Diagram...................................................................................................... 6
Signal List............................................................................................................. 7
Signal Definitions............................................................................................. 9
4
5
6
7
External Components........................................................................................ 10
PCB Layout Guidelines and Power Supply Decoupling ................................ 13
General Description........................................................................................... 15
Detailed Descriptions ........................................................................................ 16
Xtal Frequency............................................................................................... 16
Host Interface ................................................................................................ 16
7.2.1 C-BUS Operation .................................................................................... 16
Function Image™ Load and Activation.......................................................... 18
7.3.1 FI Loading from Host Controller.............................................................. 19
7.3.2 FI Loading from Serial Memory............................................................... 20
Device Control ............................................................................................... 21
7.4.1 Signal Routing......................................................................................... 21
7.4.2 Mode Control........................................................................................... 21
Transmitting DTMF Tones............................................................................. 21
AFSK/GMSK Data Modem ............................................................................ 22
7.6.1 Receiving AFSK/GMSK Signals.............................................................. 22
7.6.2 Transmitting AFSK/GMSK Data.............................................................. 23
7.6.3 Receiving AFSK/GMSK Data.................................................................. 25
7.6.4 1200bps AFSK Modem........................................................................... 26
7.6.5 9600bps GMSK Modem.......................................................................... 27
Auxiliary ADC Operation................................................................................ 27
Auxiliary DAC/RAMDAC Operation ............................................................... 28
RF Synthesiser (CMX7031 only) ................................................................... 29
7.1
7.2
7.3
7.4
7.5
7.6
7.7
7.8
7.9
7.10
Digital System Clock Generators................................................................... 32
7.10.1 Main Clock Operation.............................................................................. 33
7.10.2 System Clock Operation ......................................................................... 33
7.11
7.12
GPIO.............................................................................................................. 33
Signal Level Optimisation .............................................................................. 33
7.12.1 Transmit Path Levels .............................................................................. 34
7.12.2 Receive Path Levels................................................................................ 34
7.13
C-BUS Register Summary............................................................................. 35
7.13.1 Interrupt Operation.................................................................................. 36
7.13.2 General Notes......................................................................................... 36
8
Performance Specification................................................................................ 37
Electrical Performance .................................................................................. 37
8.1.1 Absolute Maximum Ratings .................................................................... 37
8.1.2 Operating Limits...................................................................................... 38
8.1.3 Operating Characteristics........................................................................ 39
8.1.4 Parametric Performance......................................................................... 45
C-BUS Timing................................................................................................ 47
8.1
8.2
2013 CML Microsystems Plc
Page 3
D/7031/7041_FI-4.x/5
CMLMICRO [ CML MICROCIRCUITS ]
