CMX981 Consumer Microcircuits Limited, CMX981 Datasheet - Page 26

• Manufacturer Part Number: CMX981
• Description: Advanceddigital Radio Baseband Processor (tetra Etc.)
• Manufacturer: Consumer Microcircuits Limited

Advanced Digital Radio Baseband Processor
5.11.5 $04-$07
5.11.6 $08
 2002 CML Microsystems Plc
modulator
modulator
bypassed
bypassed
Symbol
Symbol
The two least significant bits of the address are used as bits 9 and 8 of the data word.
Bit 9 controls the ramping of the transmitted data. Setting this bit high will cause the output to
ramp up to its full value. Setting this bit low will cause the output to ramp down to zero. Once the
ramp down has been completed, the transmit path enable status bit in the Status1 register is
cleared, and the transmit path can be disabled.
Bit 8 controls whether one or four symbols are read from the transmit data word (when symbol
modulator is not bypassed). When set high, the FIFO transmits all four symbols (starting with
symbol 1). When set low, only symbol 1 is transmitted.
When in symbol modulator bypass mode, the three least significant bits directly represent which of
8 supported constellation points, all on a unit circle, is to be transmitted.
Bit 7 will cause the Rx data port to transmit 32-bit frames - I data in the MSB word, Q data in the
LSB word.
Bit 6 is used to select which samples are transmitted when the serial clock is set to MCLK/4.
When set high, odd numbered samples are selected (I
samples are selected (I
Setting bit 5 causes the receive data to carry an identification bit in the LSB of the data word. The I
channel is identified by a logic "0" and the Q channel by a logic "1". This therefore reduces the
dynamic range of the receive data from 16 to 15 bits. See section 5.6.
Bit 4 will cause the receive path data sent by the Rx port to be sent least significant bit first.
Bit 3 enables the receive data path.
Bit 2 will enable read data requested by port 2 to be returned on the Rx port.
Bit 1 will enable read data requested by port 1 to be returned on the Rx port.
Setting bit 0 high will cause the receive path filter coefficients to return to their default values. This
bit should be set low while writing new coefficients.
Bit
not
Bit
port 32-bit
Set Rx
mode
Ramp
Ramp
7
up
up
9
TxData
RxSetup1
sample
symbol
Rx port
select
Multi-
Used
Not
8
6
0
, Q
0
, I
Used
2
channel
Not
Rx port
Enable
identity
, Q
7
mode
Symbol 4
5
2
).
Used
Not
6
port LSB
Transmit Data FIFO Register (Write only)
Receive Set-up Register 1
Set Rx
first
4
26
Used
Not
5
Symbol 3
Enable
receive
path
Used
3
1
Not
, Q
4
1
, I
3
for read 2
, Q
Used
Rx port
Enable
Not
3
Symbol 2
3
2
). When set low, even numbered
2
IQ Constellation point
for read 1
Enable
Rx port
1
1
Symbol 1
coefficients
Reset Rx
filter
0
0
CMX981
D/981/1