User's Manual

LE940B6 Hardware User Guide
1VV0301331 Rev. 1.8 - 2017-03-15
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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 27 lists the signals of the LE940B6 Serial Port 2.
Table 27: 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
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 28 lists the signals of the LE940B6 Serial Port 3.
Table 28: 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.