GSM/GPRS Module Series
M35 User Manual
M35_User_Manual Confidential / Released 50 / 85
3.9.1. Configuration
M35 module supports 13-bit line code PCM format. The sample rate is 8 KHz, and the clock source is 256
KHz, and the module can only act as master mode. The PCM interface supports both long and short
synchronization simultaneously. Furthermore, it only supports MSB first. For detailed information, please
refer to the table below.
Table 14: Configuration
3.9.2. Timing
The sample rate of the PCM interface is 8 KHz and the clock source is 256 KHz, so every frame contains
32 bits data, since M35 supports 16 bits line code PCM format, the left 16 bits are invalid. The following
diagram shows the timing of different combinations. The synchronization length in long synchronization
format can be programmed by firmware from one bit to eight bits. In the Sign extension mode, the high
three bits of 16 bits are sign extension, and in the Zero padding mode, the low three bits of 16 bits are
zero padding.
Under zero padding mode, you can configure the PCM input and output volume by executing
―AT+QPCMVOL‖ command. For more details, please refer to Chapter 3.9.4.
PCM Clock/Synchronization Source
PCM master mode: clock and synchronization is
generated by module
PCM master mode: 256 KHz (line)
PCM Synchronization Format
Long/short synchronization
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