20.4.8 UART1FCN1: UART1 FIFO Control 1
Bit
7
6
5
4
3
2
1
0
Name
TFRQ
TXNF
TXHOLD
TIE
RFRQ
RXTO
RIE
Access
R
R
RW
RW
R
RW
RW
Reset
1
1
0
1
0
0x0
1
SFR Page = 0x20; SFR Address: 0xD8 (bit-addressable)
Bit
Name
Reset
Access Description
7
TFRQ
1
R
Transmit FIFO Request.
Set to 1 by hardware when the number of bytes in the TX FIFO is less than or equal to the TX FIFO threshold (TXTH).
Value
Name
Description
0
NOT_SET
The number of bytes in the TX FIFO is greater than TXTH.
1
SET
The number of bytes in the TX FIFO is less than or equal to TXTH.
6
TXNF
1
R
TX FIFO Not Full.
This bit indicates when the TX FIFO is full and can no longer be written to. If a write is performed when TXNF is cleared to
0 it will replace the most recent byte in the FIFO.
Value
Name
Description
0
FULL
The TX FIFO is full.
1
NOT_FULL
The TX FIFO has room for more data.
5
TXHOLD
0
RW
Transmit Hold.
This bit allows firmware to stall transmission until cleared. When set, the UART will complete any byte transmission in pro-
gress, but no further data will be sent. Transmission will continue when the TXHOLD bit is cleared. If CTS is used for hard-
ware flow control, either TXHOLD or CTS assertion will cause transmission to stall.
Value
Name
Description
0
CONTINUE
The UART will continue to transmit any available data in the TX FIFO.
1
HOLD
The UART will not transmit any new data from the TX FIFO.
4
TIE
1
RW
Transmit Interrupt Enable.
This bit enables the TI flag to generate UART1 interrupts after each byte is sent, regardless of the THTH settings.
Value
Name
Description
0
DISABLED
The TI flag will not generate UART1 interrupts.
1
ENABLED
The TI flag will generate UART1 interrupts when it is set.
3
RFRQ
0
R
Receive FIFO Request.
Set to 1 by hardware when the number of bytes in the RX FIFO is larger than specified by the RX FIFO threshold (RXTH).
Value
Name
Description
0
NOT_SET
The number of bytes in the RX FIFO is less than or equal to RXTH.
1
SET
The number of bytes in the RX FIFO is greater than RXTH.
EFM8UB3 Reference Manual
Universal Asynchronous Receiver/Transmitter 1 (UART1)
silabs.com
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