Product Info
LTE Standard Module Series
EG95 Series Hardware Design
EG95_Series_Hardware_Design
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3.12.
PCM and I2C Interfaces
EG95 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
256
kHz, 512 kHz, 1024 kHz 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 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 256 kHz, 512 kHz, 1024 kHz or 2048 kHz PCM_CLK and an 8 kHz, 50% duty cycle PCM_SYNC.
EG95 supports 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.
125 μs
PCM_CLK
1 2
PCM_SYNC
255 256
MSB
LSB
MSB
PCM_DOUT
MSB LSB
MSB
PCM_DIN
Figure 22: Primary Mode Timing