CMX138 CML Microcircuits, CMX138 Datasheet - Page 31

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

Audio Scrambler and Sub-Audio Signalling Processor
To avoid multiple threshold IRQ’s when a noisy signal is present, the thresholds can be re-programmed
following the initial event to provide hysteresis.
See:
7.8
The Auxiliary DAC channel is programmed via the AuxDAC Control register, $A8. AuxDAC channel 1 may
also be programmed to operate as a RAMDAC which will automatically output a pre-programmed profile
at a programmed rate. The AuxDAC Control register, $A8, with b12 set, controls this mode of operation.
The default profile is a raised cosine (see Table 8), but this may be over-written with a user defined profile
by writing to Programming register P3.11. The RAMDAC operation is only available in Tx mode and, to
avoid glitches in the ramp profile, it is important not to change to IDLE or Rx mode whilst the RAMDAC is
still ramping. The AuxDAC output holds the user-programmed level during a powersave operation if left
enabled, otherwise it will return to zero.
See:
© 2008 CML Microsystems Plc
S ig n a l (a fte r in v e rte r )
o
o
o
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Auxiliary DAC/RAMDAC Operation
AuxADC and TX MOD mode - $A7 write
AuxADC data - $A9 read
AuxADC threshold data - $B5 write
AuxDAC control / data - $A8 write
T h re s h o ld
L o w
IR Q
IR Q
Figure 14 AuxADC IRQ operation
Page 31
IR Q
IR Q
T h re s h o ld
D/138_FI1.0/5
H ig h
CMX138