CMX138 CML Microcircuits, CMX138 Datasheet - Page 15

• Manufacturer Part Number: CMX138
• Description: Audio Scrambler and Sub-Audio Signalling Processor
• Manufacturer: CML Microcircuits

Audio Scrambler and Sub-Audio Signalling Processor
7.3
CMX138 can be set into many modes to suit the environment in which it is to be used. These modes are
described in the following sections and are programmed over the C-BUS: either directly to operational
registers or, for parameters that are not likely to change during operation, via the Programming register
($C8).
For basic operation:
To conserve power when the device is not actively processing an analogue signal, place the device into
Idle mode. Additional powersaving can be achieved by disabling the unused hardware blocks, however,
care must be taken not to disturb any sections that are automatically controlled.
See:
7.3.1
The CMX138 offers a flexible routing architecture, with two signal inputs, a single signal processing path
with an optional bypass and both Tx Modulation and Audio outputs. Each of the signalling processing
blocks is routed directly to the appropriate Input and Output blocks.
See:
© 2008 CML Microsystems Plc
1. Enable the relevant hardware sections via the Power Down Control register
2. Set the appropriate mode registers to the desired state (Audio, In-band, Sub-Audio etc.),
3. Select the required Signal Routing and Gain
4. Use the Mode Control register to place the device into Rx or Tx mode.
o
o
o
o
o
Device Control
Power Down Control - $C0 write
Mode Control – $C1 write
Signal Routing
Analogue Output Gain - $B1 write
AuxADC and TX MOD mode - $A7 write
Mode Control – $C1 write
DISC input
MIC input
Enable: $C0:14
Enable: $C0:15
Gain: $B0:10-8
Gain: $B0:4-2
Select: $B0:5
Input Select
Enable: $C0:13
Select: $B0:1-0
mux
Figure 5 Signal Routing
Signal Processing
Page 15
mux
MIC - MOD bypass
DISC – AUDIO
MOD output
bypass gain
Gain: $B1:12-10
Gain: $B1:15-13
Enable: $C0:11
Enable: $C0:12
Enable: $C0:1
Enable: $C0:2
Gain: $B1:5-2
Gain: $B1:9-6
output gain
Enable: $A7:13-12
gain
AUDIO
gain
Enable: $C0:6
Tx MOD
AUDIO output
MOD output
Enable: $C0:10
Enable: $C0:8
D/138_FI1.0/5
CMX138