LE910Cx
Hardware User Guide
1VV0301298 Rev. 1.05 - 2017-06-18
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Page
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8.4.1.
Modem Serial Port 1 Signals
Serial Port 1 on LE910Cx is a +1.8V UART with 7 RS232 signals. It differs from the PC-RS232 in signal
polarity (RS232 is reversed) and levels.
Table 25 lists the signals of LE910Cx Serial Port 1.
Table 25: Modem Serial Port 1 Signals
RS232
Pin No.
Signal
LE910Cx
Pad No.
Name
Usage
1
DCD -
DCD_UART
N14
Data Carrier
Detect
Output from the LE910Cx that
indicates carrier presence
2
RXD -
TX_UART
M15
Transmit line
*see Note
Output transmit line of the LE910Cx
UART
3
TXD -
RX_UART
N15
Receive line
*see Note
Input receive line of the LE910Cx
UART
4
DTR -
DTR_UART
M14
Data Terminal
Ready
Input to LE910Cx that controls the
DTE READY condition
5
GND
A2, B13,
D4…
Ground
Ground
6
DSR -
DSR_UART
P14
Data Set
Ready
Output from the LE910Cx that
indicates that the module is ready
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.