LH79524/LH79525 User’s Guide
UARTs
Version 1.0
16-19
16.3.2.9 Interrupt FIFO Level Select Register (UARTIFLS)
UARTIFLS is the Interrupt FIFO Level Select Register. The UARTIFLS Register defines
the FIFO level at which interrupts are generated to request service for the receive and
transmit FIFOs. The interrupts are generated based on a transition through a level rather
than being based on the level; that is, the design is such that the interrupts are generated
when the fill level progresses through the trigger level. The bits are reset so that the trigger
level is when the FIFOs are at the half-way mark.
Table 16-24. UARTIFLS Register
BIT
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
FIELD
///
RESET
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
RW
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
BIT
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
FIELD
///
RXIFLSEL
TXIFLSEL
RESET
0
0
0
0
0
0
0
0
0
0
0
1
0
0
1
0
RW
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RW
RW
RW
RW
RW
RW
ADDR
UART 0: 0xFF 0x034
UART 1: 0xFF 0x034
UART 2: 0xFF 0x034
Table 16-25. UARTIFLS Fields
BIT
NAME
DESCRIPTION
31:6
///
Reserved
Reading returns 0. Write the reset value.
5:3
RXIFLSEL
Trigger Points for the Receive Interrupt
000 = Receive FIFO becomes
≥
1/8 full
001 = Receive FIFO becomes
≥
1/4 full
010 = Receive FIFO becomes
≥
1/2 full
011 = Receive FIFO becomes
≥
3/4 full
100 = Receive FIFO becomes
≥
7/8 full
101 = Receive FIFO becomes full
110:111 = Invalid
2:0
TXIFLSEL
Trigger Points for the Transmit Interrupt
000 = Transmit FIFO becomes
≤
1/8 full
001 = Transmit FIFO becomes
≤
1/4 full
010 = Transmit FIFO becomes
≤
1/2 full
011 = Transmit FIFO becomes
≤
3/4 full
100 = Transmit FIFO becomes
≤
7/8 full
101 = Transmit FIFO becomes empty
110:111 = Invalid