Pcm And I2C Interfaces - Quectel EC21 Series Hardware Design

NOTE
1. Transistor circuit solution is not suitable for applications with high baud rates exceeding 460 kbps.
2. Please note that the module CTS is connected to the host CTS, and the module RTS is connected
to the host RTS.

3.12. PCM and I2C Interfaces

EC21 series 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 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.
EC21_Series_Hardware_Design
Figure 21: Reference Circuit with Transistor Circuit
LTE Standard Module Series
54 / 118