Product Info

LTE Standard Module Series
EC21_Series_Mini_PCIe_Hardware_Design
32
/ 75

AT+IPR can be used to set the baud rate of the main UART, and AT+IFC can be used to set the
hardware flow control (hardware flow control is disabled by default). See document [1] for details.
3.9. PCM and I2C Interfaces
EC21 series Mini PCIe provides one Pulse Code Modulation (PCM) digital interface and one I2C
interface.
The following table shows the pin definition of PCM and I2C interfaces that can be applied in audio
codec design.
Table 11: Pin Definition of PCM and I2C Interfaces
EC21 series 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
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.
5
The digital audio (PCM) function is only supported on Data + Voice version.
Pin Name Pin No. I/O Description Comment
PCM_CLK
5
45 DIO PCM clock 1.8 V
PCM_DOUT
5
47 DO PCM data output 1.8 V
PCM_DIN
5
49 DI PCM data input 1.8 V
PCM_SYNC
5
51 DIO PCM frame sync 1.8 V
I2C_SCL 30 DO
I2C serial clock
(for external codec)
Require external pull-up to 1.8 V.
I2C_SDA 32 DIO
I2C serial data
(for external codec)
Require external pull-up to 1.8 V.
NOTE