W83977F-A Datasheet, PDF (52/182 Pages) Winbond – WINBOND I/O

W83977F-A/ W83977G-A/ W83977AF-A/ W83977AG-A
6.2.5 UART FIFO Control Register (UFR) (Write only)
This register is used to control the FIFO functions of the UART.
7 6 54 3 210
FIFO enable
Receiver FIFO reset
Transmitter FIFO reset
DMA mode select
Reserved
Reserved
RX interrupt active level (LSB)
RX interrupt active level (MSB)
Bit 6, 7: These two bits are used to set the active level for the receiver FIFO interrupt. For example, if
the interrupt active level is set as 4 bytes, once there are more than 4 data characters in the
receiver FIFO, the interrupt will be activated to notify the CPU to read the data from the FIFO.
TABLE 6-3 FIFO TRIGGER LEVEL
BIT 7
BIT 6
0
0
0
1
1
0
1
1
RX FIFO INTERRUPT ACTIVE LEVEL (BYTES)
01
04
08
14
Bit 4, 5: Reserved
Bit 3: When this bit is programmed to logic 1, the DMA mode will change from mode 0 to mode 1 if
UFR bit 0 = 1.
Bit 2: Setting this bit to a logical 1 resets the TX FIFO counter logic to initial state. This bit will clear to
a logical 0 by itself after being set to a logical 1.
Bit 1: Setting this bit to a logical 1 resets the RX FIFO counter logic to initial state. This bit will clear to
a logical 0 by itself after being set to a logical 1.
Bit 0: This bit enables the 16550 (FIFO) mode of the UART. This bit should be set to a logical 1 before
other bits of UFR are programmed.
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