LTE Module Series
EC21 Hardware Design
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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.
I/O
Description
Comment
RI
62
DO
Ring indicator
1.8V power domain
DCD
63
DO
Data carrier detection
CTS
64
DO
Clear to send
RTS
65
DI
Request to send
DTR
66
DI
Sleep mode control
TXD
67
DO
Transmit data
RXD
68
DI
Receive data
Table 12: Pin Definition of the Debug UART Interface
Pin Name
Pin No.
I/O
Description
Comment
DBG_TXD
12
DO
Transmit data
1.8V power domain
DBG_RXD
11
DI
Receive data
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