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LTE Module Series
EG61-NA Hardware Design
EG61-NA_Hardware_Design 45 / 77
3.12. PCM and I2C Interfaces
EG61-NA provides one Pulse Code Modulation (PCM) digital interface for audio design, which supports
the following modes and one I2C interface:
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
256kHz, 512kHz, 1024kHz or 2048kHz PCM_CLK at 8kHz PCM_SYNC, and also supports 4096kHz
PCM_CLK at 16kHz PCM_SYNC.
In auxiliary mode, the data is also 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, the PCM interface operates
with a 256kHz, 512kHz, 1024kHz or 2048kHz PCM_CLK and an 8kHz, 50% duty cycle PCM_SYNC.
EG61-NA supports 16-bit linear data format. The following figures show theprimary mode’s timing
relationship with 8KHz PCM_SYNC and 2048KHz PCM_CLK, as well asthe auxiliary mode’s timing
relationship with 8KHz PCM_SYNC and 256KHz PCM_CLK.
PCM_CLK
PCM_SYNC
PCM_DOUT
MSB
LSB
MSB
125us
1 2 256255
PCM_DIN
MSB
LSBMSB
Figure 22: Primary Mode Timing