GSM/GPRS Module
M85 Hardware Design
M85_Hardware_Design Confidential / Released 38 / 92
3.7.1. UART Port
3.7.1.1. The Features of UART Port
Seven lines on UART interface
Contain data lines TXD and RXD, hardware flow control lines RTS and CTS, other control lines DTR,
DCD and RI.
Used for AT command, GPRS data, etc. Multiplexing function is supported on the UART Port. So far
only the basic mode of multiplexing is available.
Support the communication baud rates as the following:
300, 600, 1200, 2400, 4800, 9600, 14400, 19200, 28800, 38400, 57600, 115200.
The default setting is autobauding mode. Support the following baud rates for Autobauding function:
4800, 9600, 19200, 38400, 57600, 115200.
The module disables hardware flow control by default. AT command ―AT+IFC=2,2‖ is used to enable
hardware flow control.
After setting a fixed baud rate or autobauding, please send ―AT‖ string at that rate. The UART port is
ready when it responds ―OK‖.
Autobauding allows the module to detect the baud rate by receiving the string ―AT‖ or ―at‖ from the host or
PC automatically, which gives module flexibility without considering which baud rate is used by the host
controller. Autobauding is enabled by default. To take advantage of the autobauding mode, special
attention should be paid according to the following requirements:
42
DBG_TXD
Transmit data
UART Port
45
DCD
Data carrier detection
46
RI
Ring indication
47
DTR
Data terminal ready
48
CTS
Clear to send
49
TXD
Transmit data
50
RXD
Receive data
51
RTS
Request to send
Auxiliary UART Port
40
TXD_AUX
Transmit data
41
RXD_AUX
Receive data
Quectel
Confidential
