LTE Standard Module Series
EG21-G Mini PCIe Hardware Design
EG21-G_Mini_PCIe_Hardware_Design 25 / 54
EG21-G Mini PCIe provides one PCM digital interface, which supports 16-bit linear data format and the
following modes:
Primary mode (short frame synchronization, works as either master or 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. The following figure shows the timing relationship in primary mode with
8kHz PCM_SYNC and 2048kHz PCM_CLK.
PCM_CLK
PCM_SYNC
PCM_DOUT
MSB
LSB
MSB
125us
1
2
256
255
PCM_DIN
MSB
LSB
MSB
Figure 8: Timing in Primary Mode
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, the PCM interface operates with a
256kHz, 512kHz, 1024kHz or 2048kHz PCM_CLK and an 8kHz, 50% duty cycle PCM_SYNC. The
following figure shows the timing relationship in auxiliary mode with 8kHz PCM_SYNC and 256kHz
PCM_CLK.
I2C_SDA
32
IO
1.8V
I2C serial data.
Require external pull-up to 1.8V.
