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NUC126
Aug. 08, 2018
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6.23.5.4 UART Controller Transmit Delay Time Value
The UART controller programs DLY (UART_TOUT [15:8]) to control the transfer delay time between
the last stop bit and next start bit in transmission. The unit is baud. The operation is shown in Figure
6.23-4.
Start
TX
Byte (i)
Byte (i+1)
Stop
DLY
Start
Figure 6.23-4 Transmit Delay Time Operation
6.23.5.5 UART Controller FIFO Control and Status
The UART controller is built-in with a 16 bytes transmitter FIFO (TX_FIFO) and a 16 bytes receiver
FIFO (RX_FIFO) that reduces the number of interrupts presented to the CPU. The CPU can read the
status of the UART at any time during operation. The reported status information includes condition of
the transfer operations being performed by the UART, as well as 3 error conditions (parity error,
framing error, break interrupt) occur if receiving data has parity, frame or break error. UART, IrDA, LIN
and RS-485 mode support FIFO control and status function.
6.23.5.6 UART Controller Wake-up Function
The UART controller supports wake-up system function. The wake-up function includes nCTS pin,
incoming data wake-up, Received Data FIFO reached threshold wake-up, RS-485 Address Match
(AAD mode) wake-up and Received Data FIFO threshold time-out wake-up function. CTSWKF
(UART_WKSTS[0]), DATWKF (UART_WKSTS[1]), RFRTWKF (UART_WKSTS[2]), RS485WKF
(UART_WKSTS[3]) or TOUTWKF (UART_WKSTS[4]) cause the wake-up interrupt flag
WKIF(UART_INTSTS[6]) is generated. If the WKIEN (UART_INTEN[6]) is enabled, the wake-up
interrupt flag WKIF(UART_INTSTS[6]) cause the wake-up interrupt WKINT (UART_INTSTS[14]) is
generated.
nCTS Pin Wake-up
When the system is in Power-down mode and WKCTSEN (UART_WKCTL[0]) is set, the toggle of
nCTS pin can wake-up system. If the WKCTSEN (UART_WKCTL[0]) is enabled, the toggle of nCTS
pin cause the nCTS wake-up flag CTSWKF (UART_WKSTS[0]) is generated.
nCTS Wake-up Case 1 (nCTS Transition from Low to High)
Power-down mode
HCLK
nCTS
CTSWKF
stable count
CPU run
CTSACTLV (UART_MODEMSTS[8]) = 0
Note:
Stable count means HCLK source recovery stable count.
Figure 6.23-5 UART nCTS Wake-up Case1
nCTS Wake-up Case 2 (nCTS Transition from High to Low)