LE910C1
Hardware User Guide
1VV0301298 Rev. 1.08 - 2017-11-14
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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 LE910C1 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 LE910C1 serial port and vice versa for Rx.
NOTE:
DTR pin must not be pulled low in order not to prevent the UART and the entire module from
entering low power mode.
DTR can be left floating if not used.
8.4.2.
Modem Serial Port 2
Serial Port 2 on the LE910C1 is a +1.8V UART with RX and TX signals only.
The UART functionality is shared with SPI thus simultaneous of SPI and UART is not supported.
The below table lists the signals of LE910C1 Serial Port 2.
Table 26 Modem Serial Port 2 Signals
PAD
Signal
I/O
Function
Type
COMMENT
D15
TX_AUX
O
Auxiliary UART (Tx Data to DTE)
1.8V Shared with SPI_MOSI
E15
RX_AUX
I
Auxiliary UART (Rx Data to DTE)
1.8V Shared with SPI_MISO
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.