CMX980AL7 CML Microcircuits, CMX980AL7 Datasheet - Page 16

• Manufacturer Part Number: CMX980AL7
• Description: TETRA Baseband Processor
• Manufacturer: CML Microcircuits

TETRA Baseband Processor
1.5.7.1 Command Interface
1.5.7.2 Command Read Interface
1.5.7.3 Rx Data Interface
1.5.7.4 Transmission of Data
1999 Consumer Microcircuits Limited
A serial command word consists of a 16-bit frame. Each frame is marked by an active Frame Sync
event which precedes the MSB bit. A command word can be either a control word or a transmit data
word.
Command read data is either output on one of the serial read ports, or driven out in the last 8 bits
(data field) on the Cmd port. When command read data is output on a serial read port, the read
address is put in the most significant half of the word and the read data in the least significant half.
The Rx Data interface is used only for output of the I and Q received data, unless it is operating in the
mode where CmdRd data is directed to it. When data reception is enabled, I and Q received data will
be output at either 8 x or 4 x the symbol rate, under control of command register RxSetup1. (see
Section 1.5.8). This is achieved by reducing the serial interface clock rate from MCLK/2 to MCLK/4
and discarding alternate data samples under control of command registers ConfigCtrl1 and
RxSetup1. 16-bit I and Q data words are output at the Rx Data interface, I data and MSB first (by
default), on the rising edge of SClk. To facilitate channel identification of the serial data, should initial
synchronisation be lost, and synchronisation of the internal Tx symbol clock with received data, the
CMX980A has an I/Q identification mode, which is controlled by setting the RxIdentMode bit in the
RxSetup1 Register.
The address of the Tx FIFO is given consecutive locations ($0x04-$0x07), which allows the address
bits A1 and A0 (bits 11 and 10) of the Command Transmit Data Serial Word to be utilised as transmit
control functions. Data to be transmitted can be in either one or four 2-bit symbol blocks, which are
subsequently modulated into the DQPSK constellation, or in 3-bit words, which map directly into
constellation points according to the table shown below:
code
3 bit
Q
I
MSB
MSB
MSB
W / R
15
15
15
1
0
000
1
0
14
14
14
Tx Data Address
0.7071
0.7071
001
Read Address
Command Transmit Data Serial Word
Address
Command Control Serial Word
Command Read Serial Word
010
0
1
10
Constellation map
U/D
9
-0.7071
0.7071
16
8 7
8
011
7
4/1
8
7
100
-1
0
Data
Data
Tx Data
-0.7071
-0.7071
101
110
-1
0
LSB
LSB
LSB
0
0
0
-0.7071
0.7071
111
CMX980A
D/980A/3