Uart Interfaces - Quectel EC21 Series Hardware Design

3.11. UART Interfaces

The module provides two UART interfaces: the main UART interface and the debug UART interface. The
following shows their features.

The main UART interface supports 4800, 9600, 19200, 38400, 57600, 115200, 230400, 460800,
921600 and 3000000bps baud rates, and the default is 115200bps. The interface is used for data
transmission and AT command communication.

The debug UART interface supports 115200bps baud rate. It is used for Linux console and log
output.
The following tables show the pin definition of the main UART interface.
Table 11: Pin Definition of the Main UART Interface
Pin Name Pin No.
RI 62
DCD 63
CTS 64
RTS 65
DTR 66
TXD 67
RXD 68
Table 12: Pin Definition of the Debug UART Interface
Pin Name Pin No.
DBG_TXD 12
DBG_RXD 11
EC21_Hardware_Design
I/O Description
DO Ring indicator
DO Data carrier detection
DO Clear to send
DI Request to send
DI Sleep mode control
DO Transmit data
DI Receive data
I/O Description
DO Transmit data
DI Receive data
Confidential / Released
LTE Module Series
EC21 Hardware Design
Comment
1.8V power domain
Comment
1.8V power domain
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