Figure 6.12-17 Structure Of Rs-485 Frame - Nuvoton ISD94124BYI Technical Reference Manual

5. Determine auto direction control by programming RS485AUD (UART_ALTCTL[10]).
TX pin output
RTSSTS
(UART_MODEM[13])
Note: RS485AUD(UART_ALTCTL[10]) must be set to 1, and RTSACTLV(UART_MODEM[9]) must be set to
6.12.5.10 PDMA Transfer Function
UART controller supports PDMA transfer function.
By configuring PDMA parameter and set UART_DAT as the PDMA destination address. When
TXPDMAEN (UART_INTEN[14]) is set to 1, the controller will issue request to PDMA controller to
start the PDMA transmission process automatically.
By configuring PDMA parameter and set UART_DAT as the PDMA source address. When
RXPDMAEN (UART_INTEN[15]) is set to 1, the controller will start the PDMA reception process.
UART controller will issue request to PDMA controller automatically when there is data in the RX
FIFO buffer.
Note: If STOPn (PDMA_STOP[n]) is set to stop UART RXPDMA task and the UART receive is not
finish. UART controller will complete the transfer and stored current receive data in receive buffer.
By reading RXEMPTY (UART_FIFOSTS[14]) to check there is valid data in receive buffer or not.
Sep 9, 2019
ISD94100 Series Technical Reference Manual
RX
TX
nRTS
UART / RS- 485 Controller
Start
D0 D1 D2 D3
bit
Driver Enable

Figure 6.12-17 Structure of RS-485 Frame

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Driver Enable
RS- 485 Transceiver
Stop
D4 D5 D6 D7 P
bit
0.
Differential Bus
Rev1.09