W83977ATF Datasheet, PDF (57/207 Pages) Winbond – WINBOND I/O

W83977ATF
PRELIMINARY
Bit 2: FERI. This bit indicates that the RI pin has changed from low to high state after HSR was read
by the CPU.
Bit 1: TDSR. This bit indicates that the DSR pin has changed state after HSR was read by the CPU.
Bit 0: TCTS. This bit indicates that the CTS pin has changed state after HSR was read.
3.2.5 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 3-3 FIFO TRIGGER LEVEL
BIT 7
BIT 6
RX FIFO INTERRUPT ACTIVE LEVEL (BYTES)
0
0
01
0
1
04
1
0
08
1
1
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.
Publication Release Date: April 1998
-47 -
Revision 0.52