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27
Hardware Development Guide
ME3616
2.11.
UART
INTERFACE
The module provides two UART interfaces: Main UART Port and Debug UART Port. The Main UART Port can
support 4-wires&2-wires while the Debug UART Port support 2-wires. The following show the different features
Main UART interface support 110,300,1200,2400,4800,9600,19200,38400,57600,115200,230400, 460800,
921600 bps baud rate, the default is 115200bps, This interface can be used for data transmission; AT
communication
Main UART interface supported auto detectable rate are:110,300,1200,2400,4800,9600,19200, 38400,
57600,115200, supported fixed-only rate are:0,9600,19200,38400,57600,115200,230400,460800,921600.
The baud rate adaptation is only for the main UART interface of the module. The MCU of the customer must
start from the power-on of the module (without delay) and send “AT\r\n” to the module every 200-500ms until
the module returns OK. At this time, it is deemed that the baud rate adaptation is successful. Can send other AT
commands
Debug UART interface supports 115200bps baud rate. It can be used for software debug and firmware
upgrade. The module is designed as the DCE (Data Communication Equipment), following the traditional DCE-DTE
(Data Terminal Equipment) connection.
The following tables show the pin definition of these two UART interfaces.
Table 2-13 Pin Definition of the Main UART Interface
Pin Name
Pin NO.
I/O
Description
Comment
UART1_CTS
7
DI
Clear to send
1.8V
UART1_RTS
8
DO
Request to send
1.8V
UART1_TXD
9
DO
Transmit data
1.8V
UART1_RXD
10
DI
Receive data
1.8V
2.11.1.
UART
CONNECTION
Two normal connections for UART are shown in the figures below:
1.
3-wire UART connection:
TXD
RXD
RTS
CTS
DTR
DCD
RING
Serial Port
Serial Port
(DCE)
(DTE)
GND
GND
UART_TXD
UART_RXD
UART_RTS
UART_CTS
UART_DTR
UART_DCD
UART_RI