LE940B6 HW User Guide
Rev. 2.02
Page 75 of 111
2020-01-10
RS232 Pin#
Signal
Pad No.
Name
Usage
7
CTS -
CTS_UART
AK19
Clear to
Send
Output from LE940B6
controlling the Hardware flow
control
8
RI -
RI_UART
AJ18
Ring
Indicator
Output from LE940B6 indicating
the Incoming call condition
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 LE940B6 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 LE940B6 serial port and vice versa for Rx.
8.2.2.
Modem Serial Port 2
On the LE940B6, Serial Port 2 is a +1.8V UART with Rx and Tx signals only.
Table 26 lists the signals of the LE940B6 Serial Port 2.
Table 26: Modem Serial Port 2 Signals
PAD
Signal
I/O
Function
Type
Comment
AB19 TXD_AUX
O
Auxiliary UART (Tx Data to DTE)
1.8V
AD19 RXD_AUX I
Auxiliary UART (Rx Data to DTE)
1.8V
Provided
to
Dekra
under
NDA
Distribution
is
Prohibited
except
for
Dekra
employees
with
a Need
to
know