UART Registers
1645
SLAU723A – October 2017 – Revised October 2018
Copyright © 2017–2018, Texas Instruments Incorporated
Universal Asynchronous Receiver/Transmitter (UART)
26.5.9 UARTIFLS Register (Offset = 0x34) [reset = 0x12]
UART Interrupt FIFO Level Select (UARTIFLS)
The UARTIFLS register is the interrupt FIFO level select register. You can use this register to define the
FIFO level at which the TXRIS and RXRIS bits in the UARTRIS register are triggered.
The interrupts are generated based on a transition through a level rather than being based on the level.
That is, the interrupts are generated when the fill level progresses through the trigger level. For example, if
the receive trigger level is set to the half-way mark, the interrupt is triggered as the module is receiving the
9th character.
Out of reset, the TXIFLSEL and RXIFLSEL bits are configured so that the FIFOs trigger an interrupt at the
half-way mark.
UARTIFLS is shown in
and described in
Return to
Figure 26-12. UARTIFLS Register
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
RESERVED
R-0x0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
RESERVED
RXIFLSEL
TXIFLSEL
R-0x0
R/W-0x2
R/W-0x2
Table 26-12. UARTIFLS Register Field Descriptions
Bit
Field
Type
Reset
Description
31-6
RESERVED
R
0x0
5-3
RXIFLSEL
R/W
0x2
UART Receive Interrupt FIFO Level Select.
The trigger points for the receive interrupt are as follows:
0x0 = RX FIFO >= 1/8 full
0x1 = RX FIFO >= 1/4 full
0x2 = RX FIFO >= 1/2 full (default)
0x3 = RX FIFO >= 3/4 full
0x4 = RX FIFO >= 7/8 full
0x5 = Reserved
0x6 = Reserved
0x7 = Reserved
2-0
TXIFLSEL
R/W
0x2
UART Transmit Interrupt FIFO Level Select.
The trigger points for the transmit interrupt are as follows: If the EOT
bit in UARTCTL is set, the transmit interrupt is generated once the
FIFO is completely empty and all data including stop bits have left
the transmit serializer.
In this case, the setting of TXIFLSEL is ignored.
0x0 = TX FIFO <= 7/8 empty
0x1 = TX FIFO <= 3/4 empty
0x2 = TX FIFO <= 1/2 empty (default)
0x3 = TX FIFO <= 1/4 empty
0x4 = TX FIFO <= 1/8 empty
0x5 = Reserved
0x6 = Reserved
0x7 = Reserved