User's Guide

LE910Cx HW User Guide
Doc#: 1VV0301298
Rev. 13.0 Page 71 of 124 2019-07-15
RS232
Pin#
Signal
Pad No.
Name
Usage
7
RTS -
RTS_UART
L14
Request to
Send
Input to LE910Cx controlling the
Hardware flow control
8
CTS -
CTS_UART
P15
Clear to Send
Output from LE910Cx
controlling the Hardware flow
control
9
RI -
RI_UART
R14
Ring
Indicator
Output from LE910Cx indicating
the Incoming call condition
NOTE:
DCD, DTR, DSR, RI signals that are not used for UART functions can be
configured as GPIO using AT commands.
NOTE:
To avoid a back-powering effect, it is recommended to avoid having any
HIGH logic level signal applied to the digital pins of the module when it is
powered OFF or during an ON/OFF transition.
NOTE:
For minimum implementations, only the TXD and RXD lines need be
connected. The other lines can be left open provided a software flow control
is implemented.
NOTE:
According to V.24, Rx/Tx signal names refer to the application side;
therefore, on the LE910Cx side, these signal are in the opposite direction:
TXD on the application side will be connected to the receive line (here
named TXD/ RX_UART) of the LE910Cx serial port and vice versa for Rx.
NOTE:
The DTR pin is used to control the UART and system sleep
Pulling the DTR pin low prevents the UART and the entire module from
entering low power mode.
DTR can be left floating if not used (DTR is internally pulled high).