CMX138 CML Microcircuits, CMX138 Datasheet - Page 41

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

Audio Scrambler and Sub-Audio Signalling Processor
Note: when $A8 b12 is set to 1, writing data to this register controls the RAMDAC settings. Writing to
AuxDAC whilst the RAMDAC is still ramping may cause un-intended operation. In this mode b9 to b0
perform the following functions:
b9
b8
b7
b6
b2
b1
b0
To initiate a RAMDAC ramp up write:
To initiate a RAMDAC ramp down, write: $9001
Note that initiating a RAMDAC scan will automatically bring AuxDAC1 out of powersave. To place
AuxDAC1 back into powersave, it must be written to explicitly. Do NOT change IDLE / Rx / Tx mode
whilst the RAMDAC is still ramping.
9.1.5
b15, b14 threshold status
b13 reserved
b12 reserved
b11 reserved
b10 reserved
b9 –b0
© 2008 CML Microsystems Plc
15
Threshold
status
reserved, clear to 0
reserved, clear to 0
reserved, clear to 0
RAMDAC RAM access, 0 resets the internal RAMDAC address pointer
Scan direction:
Autocycle
RAMDAC start
AuxADC data - $A9 read
14
AuxADC data or last reading (unsigned) - $000 = DV
13
x
12
x
0 = ramp down
0 = disable
0 = stop
b5
11
x
b15
b14
0
0
0
0
1
1
1
1
10
x
b4
= 1
= 0
= 1
= 0
$9005
9
0
0
1
1
0
0
1
1
1 = ramp up
1 = continuous ramp up/down
1 = start RAMDAC ramping
signal is above the high threshold
signal is below the high threshold
signal is below the low threshold
signal is above the low threshold
b3
Page 41
8
0
1
0
1
0
1
0
1
7
RAMDAC scan time
divider
DD
1024
6
512
256
128
, $3FF = DV
64
32
16
8
AUX ADC data
time(ms)
5
10.50
5.25
2.63
1.31
0.66
0.33
0.16
0.08
4
SS
3
2
D/138_FI1.0/5
1
CMX138
0