w83977ctf Winbond Electronics Corp America, w83977ctf Datasheet - Page 60

• Manufacturer Part Number: w83977ctf
• Description: Winbond I/o
• Manufacturer: Winbond Electronics Corp America

TABLE 3-3 FIFO TRIGGER LEVEL
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
Bit 2: Setting this bit to a logical 1 resets the TX FIFO counter logic to initial state. This bit will clear to
Bit 1: Setting this bit to a logical 1 resets the RX FIFO counter logic to initial state. This bit will clear to
Bit 0: This bit enables the 16550 (FIFO) mode of the UART. This bit should be set to a logical 1
3.2.6 Interrupt Status Register (ISR) (Read only)
This register reflects the UART interrupt status, which is encoded by different interrupt sources into 3
bits.
Bit 7, 6: These two bits are set to a logical 1 when UFR bit 0 = 1.
Bit 5, 4: These two bits are always logic 0.
Bit 3: In 16450 mode, this bit is 0. In 16550 mode, both bit 3 and 2 are set to a logical 1 when a time-
Bit 2, 1: These two bits identify the priority level of the pending interrupt, as shown in the table below.
Bit 0: This bit is a logical 1 if there is no interrupt pending. If one of the interrupt sources has
BIT 7
UFR bit 0 = 1.
a logical 0 by itself after being set to a logical 1.
a logical 0 by itself after being set to a logical 1.
before other bits of UFR are programmed.
out interrupt is pending.
occurred, this bit will be set to a logical 0.
0
0
1
1
BIT 6
0
1
0
1
7
6
RX FIFO INTERRUPT ACTIVE LEVEL (BYTES)
5
0
4
0
3
-51 -
2
01
04
08
14
1
0
0 if interrupt pending
Interrupt Status bit 0
Interrupt Status bit 1
Interrupt Status bit 2
FIFOs enabled
FIFOs enabled
Publication Release Date: March 1999
W83977EF/ CTF
PRELIMINARY
Revision A1