User's Manual

GSM/GPRS Module Series
M35 User Manual
M35_User_Manual Confidential / Released 49 / 85
3.9. PCM Interface
Pulse-code modulation (PCM) is a converter that changes the consecutive analog audio signal to discrete
digital signal. The whole procedure of Pulse-code modulation contains sampling, quantizing and
encoding.
M35 supports PCM interface. It is used for digital audio transmission between the module and the device.
This interface is composed of PCM_CLK, PCM_SYNC, PCM_IN and PCM_OUT signal lines.
The module disables PCM interface by default. AT command ―AT+QPCMON‖ is used to configure PCM
interface.
Table 13: Pin Definition of PCM Interface
1)
When using the PCM interface, STATUS pin can be used as PCM_SYNC pin, RI pin can be used as
PCM_CLK pin.
Ref level
0
4.8
Vpp
AOUT2
Output
Differential
Load resistance
8
Load Resistance
Reference level
0
2×VBAT
Vpp
Single-ended
Load resistance
8
Load Resistance
Reference level
0
VBAT
Vpp
Pin NO.
Pin Name
Description
1)
Alternate Function
12
PCM_SYNC
PCM frame synchronization output
STATUS
26
PCM_CLK
PCM clock output
RI
41
PCM_OUT
PCM data output
42
PCM_IN
PCM data input
NOTE