Pcm Interface - Quectel LTE-A Module Series Hardware Design

3.9. PCM Interface*

EM120R-GL&EM160R-GL support audio communication via Pulse Code Modulation (PCM) digital
interface. The PCM interface supports the following modes:
⚫
Primary mode (short frame synchronization, works as both master and slave)
⚫
Auxiliary mode (long frame synchronization, works as master only)
In primary mode, the data is sampled on the falling edge of the PCM_CLK and transmitted on the rising
edge. The PCM_SYNC falling edge represents the MSB. In this mode, the PCM interface supports 256,
512, 1024 or 2048 kHz PCM_CLK at 8 kHz PCM_SYNC, and also supports 4096 kHz PCM_CLK at
16 kHz PCM_SYNC.
In auxiliary mode, the data is sampled on the falling edge of the PCM_CLK and transmitted on the rising
edge. The PCM_SYNC rising edge represents the MSB. In this mode, PCM interface operates with a
256 kHz PCM_CLK and an 8 kHz, 50% duty cycle PCM_SYNC only.
EM120R-GL&EM160R-GL support 16-bit linear data format. The following figures show the primary
mode's timing relationship with 8 kHz PCM_SYNC and 2048 kHz PCM_CLK, as well as the auxiliary
mode's timing relationship with 8 kHz PCM_SYNC and 256 kHz PCM_CLK.
PCM_CLK
PCM_SYNC
PCM_OUT
PCM_IN
EM120R-GL&EM160R-GL_Hardware_Design
EM120R-GL&EM160R-GL Hardware Design
125 μs
1 2
MSB LSB
MSB LSB
Figure 25: Primary Mode Timing
LTE-A Module Series
255 256
MSB
MSB
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