User's Guide

LE940B6 HW User Guide
Rev. 2.02
Page 76 of 111 2020-01-10
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:
The Auxiliary UART is used as the SW main debug console. It is required to
place test points on this interface even if not used.
8.2.3. Modem Serial Port 3
Serial port 3 is a +1.8V UART with all 4 RS232 signals. It differs from the PC-RS232 in the
signal polarity (RS232 is reversed) and levels. Table 27 lists the signals of the LE940B6
Serial Port 3.
Table 27: Modem Serial Port 3 Signals
PAD
Signal
I/O
Function
Type
Comment
AM9
UART3_TXD
I
Serial data input (TXD) from DTE
1.8V
AM11
UART3_RXD
O
Serial data output (RXD) to DTE
1.8V
AM13
UART3_RTS
I
Input for Request to Send (RTS) from
DTE
1.8V
AM15
UART3_CTS
O
Output for Clear to Send (CTS) to DTE
1.8V
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.
Provided to Dekra under NDA
Distribution is Prohibited except for
Dekra employees with a Need to know