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UART0 and UART1
LH75400/01/10/11 (Preliminary) User’s Guide
19-18
7/15/03
19.3.1.11 Interrupt FIFO Level Select Register
IFLS is the Interrupt FIFO Level Select Register. The active bits used in this register are
Read/Write.
The IFLS Register defines the FIFO level at which interrupts are generated to request ser-
vice 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 19-21. IFLS 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
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
BIT
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
FIELD
///
R
E
CEIVE
I
N
TERRU
PT
FIFO LEVEL SELECT
T
R
ANSMIT INT
E
RRUPT
FIFO LEVEL SELECT
RESET
0
0
0
0
0
0
0
0
0
0
0
1
0
0
1
0
RW
R
R
R
R
R
R
R
R
R
R
RW
RW
RW
RW
RW
RW
ADDR
UART0: 0xFF 0x034
UART1: 0xFF 0x034
Table 19-22. IFLS Register Definitions
BIT
NAME
DESCRIPTION
31:6
///
Reserved
Do not modify.
5:3
RECEIVE
INTERRUPT FIFO
LEVEL SELECT
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.
101:111 = Reserved.
2:0
TRANSMIT
INTERRUPT FIFO
LEVEL SELECT
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.
101:111 = Reserved.