AIS Baseband IC with/without RF Synthesiser
CMX7032/CMX7042
Name
Description
DataBitResetN_Rx1
DataBitResetN_Rx2
DataBitResetN_Tx
DAC_Write
Reset Rx1 data buffer pointer
Copy N bits (1 to 15) from Rx1 data buffer to Read Data register 0
Increment the data buffer pointer
Reset Rx2 data buffer pointer
Copy N bits (1 to 15) from Rx1 data buffer to Read Data register 0
Increment data buffer pointer
Reset Tx data buffer pointer
Copy N bits (1 to 15) from Write Data register 0 to Txdata buffer
Increment data buffer pointer
Interprets each of the first 1 to 4 words in the Write Data registers as a write command for the
Auxiliary DACs
7.5.7 Modem Tasks and Codes
Modem tasks transmit data on the MOD1 and MOD2 output pins or receive and recover data from the
RXnN pins. Modem tasks also coordinate data transfer between the Data Buffers and their respective
Modems.
Note that for receive tasks a 1 or 2 at the end of the task name refers to the Rx channel which is being
addressed.
Table 5 Modem Tasks
Name
NULL
Description
No command – takes no action
AbortRx1
AbortRx2
AbortTx
ECM
Abort the ongoing modem task on Rx1, Rx2 or Tx
Enter Configuration mode
Rx Tasks
Rx Raw bit = 0
RXB1
Rx Raw bit = 1
Rx Burst: Wait for a training sequence, then
demodulate, decode and store the burst
RXB2
RXR1
RXR2
Demodulate and store N words. N is
defined by Rx data count register
Tx Tasks
Tx Raw bit = 0
TXB
Tx Raw bit = 1
TDBS
Code and transmit AIS message using contents
of data buffer. Start on next SLOTCLK
Transmit contents of data buffer. Start on
next SLOTCLK
TDB
Transmit N data bits from the Tx mod
buffer. Start as soon as modulator is free
Transmit pseudorandom bit sequence
Repeatedly transmit one word
Hardware Control
PRBS
TRW
HCT
7.6 Transmission format
The CMX7032/CMX7042 is capable of transmitting AIS data in either raw mode or burst mode. AIS Carrier
Sensing (CSTDMA) for Class B systems is supported.
In AIS raw mode, data is passed directly from the Tx Data Buffer to the GMSK modulator, so the µC will be
responsible for sending any necessary training sequences and performing HDLC processing and NRZI
coding.
In AIS burst mode, the CMX7032/CMX7042 uses an internal message buffer to assemble an entire
message (up to 5 slots) to which it automatically adds the training sequence, start/stop flags, CRC, bit
stuffing and NRZI coding prior to transmission.
After setting up the appropriate registers, transmission is initiated by issuing a Tx Burst or Tx Raw task.
2012 CML Microsystems Plc
33
D/7032/42_FI1.2/13
CMLMICRO [ CML MICROCIRCUITS ]
