Marine VHF Audio and Signalling Processor
CMX885
Transmit functions
MOD1 gain
$B0
b14-11
Output 1
Mux
$B1
b9,8
TX
MOD
mode
$A7
Programmable tone
DTMF
Inband
signalling
Mux
$B1
b7
b12,13
Mux
$C1
b14-2
Output
2
MOD2 gain
$B0
b10-8
Raw mode
Data
Modem
DSC Modem
Formatted mode
Audio processing
Pre-
Emphasis
Channel
filtering
Soft
Limiter
Scrambler
Audio
Routing
$B1
Receive functions
Output
1
b6
Audio Gain
$B0
b3-0
Mic I/P
ALT I/P
Disc I/P
Input 2
$B1
b15-13
In-band signalling
Mux
VBias
VBias
VBias
Mux
$B1
b3,2
$C1
b11
HPF
DTMF
Mux
$B1
b5,4
Mux
$C1
b4
Raw mode
BPF
BPF
Data Modem
DSC Modem
Modem
Formatted mode
Input 1
$B1
b12-10
Mux
$C1
b13
NWR
Modem
Channel
filter
De-
emphasis
De-
scrambler
Audio
processing
HPF
Figure 5 Signal Routing
The analogue gain/attenuation of each input and output can be set individually, with additional fine gain
control available via the Programming register.
See:
o
o
Analogue Output Gain – $B0 write
Input Gain and Output Signal Routing – $B1 write
7.4.2 Mode Control
The CMX885 operates in one of three modes:
o
o
o
Idle
Rx
Tx
At power-on or following a Reset, the device will automatically enter Idle mode, which allows for the
maximum powersaving whilst still retaining the capability of monitoring the four ADC inputs (if enabled). It
is only possible to write to the Programming register whilst in Idle mode.
See:
o
Mode Control – $C1 write
© 2010 CML Microsystems Plc
17
D/885/3
CMLMICRO [ CML MICROCIRCUITS ]
