User's Guide

UL865 Hardware User Guide
1VV0301050 Rev 2 – 2013-10-09
NOTE:
According to V.24, RX/TX signal names are referred to the application side, therefore on the
UL865 side these signal are on the opposite direction: TXD on the application side will be
connected to the receive line (here named TXD/ rx_uart ) of the UL865 serial port and vice
versa for RX.
NOTE:
For a minimum implementation, only the TXD and RXD lines can be connected, the other
lines can be left open provided a software flow control is implemented.
NOTE:
In order to avoid a back powering effect it is recommended to avoid having any HIGH logic
level signal applied to the digital pins of the UL865 when the module is powered off or during
an ON/OFF transition.
The secondary serial port on the UL865 is a CMOS1.8V with only the RX and TX signals.
The signals of the UL865 serial port are:
PAD
Signal
I/O
Function
Type
Comment
44
RXD_AUX
I
Auxiliary UART (RX Data from DTE)
CMOS 1.8V
Shared with SPI_MISO
45
TXD_AUX
O
Auxiliary UART (TX Data to DTE)
CMOS 1.8V
Shared with SPI_MOSI
NOTE:
Due to the shared functions, when the SPI port is used, it is not possible to use the SPI port.
NOTE:
In order to avoid a back powering effect it is recommended to avoid having any HIGH logic
level signal applied to the digital pins of the UL865 when the module is powered off or during
an ON_OFF transition.