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Rev. 1.00
503 of 576
January 28, 2022
32-Bit Arm
®
Cortex
®
-M0+ MCU
HT32F54231/HT32F54241/HT32F54243/HT32F54253
23 Universal
Asynchronous Receiver T
ransmitter (UART)
23 Universal
Asynchronous Receiver T
ransmitter (UART)
UART Status & Interrupt Flag Register – URSIFR
This register contains the corresponding UART status.
Offset:
0x010
Reset value: 0x0000_0180
31
30
29
28
27
26
25
24
Reserved
Type/Reset
23
22
21
20
19
18
17
16
Reserved
Type/Reset
15
14
13
12
11
10
9
8
Reserved
TXC
Type/Reset
RO 1
7
6
5
4
3
2
1
0
TXDE
Reserved
RXDR
BII
FEI
PEI
OEI
Reserved
Type/Reset RO 1
RO 0 WC 0 WC 0 WC 0 WC 0
Bits
Field
Descriptions
[8]
TXC
Transmit Complete
0: Either the transmit data register (TDR) or transmit shift register (TSR) is not empty
1: Both the transmit data register (TDR) and transmit shift register (TSR) are empty
When this bit is set, an interrupt will be generated if the TXCIE bit in the URIER
register is set to 1. This bit is cleared by a write to the URDR register with new data.
[7]
TXDE
Transmit Data Register Empty
0: Transmit data register is not empty
1: Transmit data register is empty
The TXDEIE bit is set by hardware when the content of the transmit data register
is transferred to the transmit shift register (TSR). An interrupt will be generated if
the TXDEIE bit in the URIER register is set to 1. This bit is cleared by a write to the
URDR register with new data.
[5]
RXDR
RX Data Ready
0: Receive data register is empty
1: The received data in receive data register is ready to read
This bit is set by hardware when the content of the receive shift register (RSR) has
been transferred to the URDR register. An interrupt will be generated if the RXDRIE
bit in the URIER register is set to 1. It is cleared by a read to the URDR register.
[4]
BII
Break Interrupt Indicator
This bit is set to 1 whenever the received data input is held in the “spacing state”
(logic 0) for longer than a full character transmission time, which is the total time of
“start bit” + data bits + “parity” + “stop bits” duration. Writing 1 to this bit clears the
flag.
[3]
FEI
Framing Error Indicator
This bit is set 1 whenever the received character does not have a valid stop bit,
which means, the stop bit following the last data bit or parity bit is detected as logic
0. Writing 1 to this bit clears the flag.
[2]
PEI
Parity Error Indicator
This bit is set to 1 whenever the received character does not have a valid parity bit.
Writing 1 to this bit clears the flag.