
FPGA Registers
EPU-4562 Programmer’s Reference Manual
38
UARTMODE1 – UART MODE REGISTER #1
When the COM Transceiver Mode is set to RS422/485 (in the
XCVRMODE
register) and the
RS-485 Automatic Direction Control is enabled (e.g.,
UART1_485ADC
set to ‘1’) then the
transceiver Tx output is enabled. When there are bytes to transmit and the transceiver Tx output
is disabled (i.e., tri-stated) when there are no bytes to transmit.
When the COM Transceiver Mode is set to RS422/485 and Automatic Direction Control is
disabled (e.g.,
UART1_485ADC
set to ‘0’) then the UART is in Manual Direction Control mode
and the transceiver Tx output enable is controlled by software using the
RTS
bit in the UART
Modem Control Register.
RTS
= '0' - Transceiver Tx output is enabled.
RTS
= '1' - Transceiver Tx output is disabled (i.e., tri-stated).
Warning:
Terminal software, expecting an RS-232 port, may set
RTS
to '1' and disable the
transmitter when initializing an RS-422/485 port in Manual Direction Control mode. Application
software that handles the RS-422/485 port should set
RTS
to '0' to enable transmitting when in
Manual Direction Control mode.
Reset type is Platform.