CMX649 CML Microcircuits, CMX649 Datasheet - Page 26

• Manufacturer Part Number: CMX649
• Description: ADM Codec
• Manufacturer: CML Microcircuits

ADM Codec
PCM Input
Select
(Bits 14 – 13)
ADM Input
Select
(Bits 12 – 11)
Decoder Output
Select
(Bits 10 – 9)
Reserved
(Bit 8)
2003 CML Microsystems Plc
Allows selection of the input to the PCM rate converting filter.
If PCM filter interpolates, the decoder can digitally transcode a PCM signal to ADM.
If PCM filter decimates, the decoder can digitally transcode an ADM signal to PCM.
This bit is reserved and should be set to a logic 0.
Bit 14
Bit 12
Bit 10
0
1
1
0
0
1
0
0
1
1
Bit 13
Bit 11
Bit 9
X
X
0
1
0
1
0
1
0
1
PCM filter decimates ADM estimator output.
PCM words available in register $D6.
PCM filter interpolates linear PCM input from
burst mode interface (RX DATA pin).
This selection must be made in conjunction
with the CODEC MODE CONTROL Register
($70). Note that the burst interface expands
the PCM filter.
PCM filter interpolates linear PCM input from
C-BUS interface via the DECODE LINEAR
PCM INPUT Register($D7).
ADM decoder input from the RX DATA pin.
(Normal mode operation).
ADM decoder gets input from C-BUS via the
DECODE ADM INPUT Register ($D8). This
could be used to force in an idle pattern or to
play out an arbitrary stored signal.
(Alternate ADM input operation).
ADM input from digital feedback. When ADM
input comes from digital feedback it will
transcode from PCM to ADM. PCM filter
must be set to interpolate. In this mode the
analog interface can be powered down since
all signal processing is done digitally.
(PCM to ADM transcoding input operation).
ADM estimator output drives decoder output.
ADM estimator output summed with PCM
interpolation filter output drives decoder
output. The ADM and PCM signals can be
input from any combination of RX DATA pin
and C-BUS input registers.
Direct PCM test mode.
Interpolated PCM output.
Law or Alaw signals to linear PCM prior to
26
Selected Decoder Output
Selected PCM Input
Selected ADM Input
CMX649
D/649/2