CMX649E3 CML Microcircuits, CMX649E3 Datasheet - Page 37

• Manufacturer Part Number: CMX649E3
• Description: ADM Codec
• Manufacturer: CML Microcircuits

ADM Codec
DECODE ADM OUTPUT READ Register ($DA)
Decode ADM
Output
(Bits 7 – 0)
ENCODE VAD LEVEL OUTPUT READ Register ($E4)
Encode VAD
Level Output
(Bits 15 – 0)
ENCODE OFFSET LEVEL OUTPUT READ Register ($E5)
Encode Offset
Level Output
(Bits 15 – 0)
ENCODE LINEAR PCM OUTPUT READ Register ($E6)
Encode Linear
PCM Output
(Bits 15 – 0)
2002 CML Microsystems Plc
The equation for the PCM register value is:
This register allows ADM bits to be read via C-BUS and is updated every eighth bit.
Bit 0 of the CODEC INTERRUPT CONTROL Register ($81) can be set to a logic 1 to
enable interrupts informing a micro-controller when the register has been updated.
When the decoder is set to transcode from PCM to ADM the ADM bits are available
via this register.
These bits indicate the average amplitude of the envelope of the audio signal. This
negative 2’s complement number can range from $0 to $8000 (0 to -32768) and can
be used to assist in calculating an appropriate value to be programmed into the
ENCODE VAD THRESHOLD Register ($E2).
The equation for the VAD level register value is:
When offset tracking is enabled these bits indicate the average amplitude of the
measured offset. The number format is 2’s complement and ranges from $8000
through $0000 to $7FFF (-32768 to 32767). It can be used as an appropriate value to
be programmed into the ENCODE OFFSET LEVEL Register ($E3) if offset tracking
will be disabled.
The equation for the offset value is:
When offset tracking is disabled these bits indicate the offset level as input by the
user in register $E3.
This register containes the linear PCM equivalent of the encoded ADM signal. The
number format is 2’s complement and ranges from $8000 through $0000 to $7FFF
(-32768 to 32767). Bit 5 of the CODEC INTERRUPT CONTROL Register ($81) can
be set to a logic 1 to enable interrupts informing a micro-controller when the register
has been updated.
The equation for the PCM register value is:
Register
Register
Register
Register
Value
Value
Value
Value
37
(DAC
(DAC
(DAC
(DAC
-1
(Envelope
Full
Full
Full
Full
(Offset
(PCM
(PCM
Scale
Scale
Scale
Scale
voltage)
Voltage)
voltage)
voltage
Reference
Reference
Reference
Reference
level)
2
2
2
15
15
18
Voltage)
Voltage)
Voltage)
Voltage)
2
15
CMX649
D/649/1