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Rev. 1.00
496 of 576
January 28, 2022
32-Bit Arm
®
Cortex
®
-M0+ MCU
HT32F54231/HT32F54241/HT32F54243/HT32F54253
23 Universal
Asynchronous Receiver T
ransmitter (UART)
Baud Rate Generation
The baud rate for the UART receiver and transmitter are both set with the same values. The baud rate
divisor, BRD, has the following relationship with the UART clock which is known as CK_UART.
Baud Rate Clock = CK_UART / BRD
Where the CK_UART clock is the APB clock connected to the UART while the BRD range is from
16 to 65535.
CK_UART
BRD = 18
Reference
Divisor Clock
Start Bit
Bit0
Bit1
Bit2
Bit3
Bit4
Bitn
Parity Bit
Stop Bit
Next Start
Bit
~~ ~~
n = 7 ~ 8
~~~~
Figure 182. UART Clock CK_UART and Data Frame Timing
Table 58. Baud Rate Deviation Error Calculation – CK_UART = 40 MHz
Baud Rate
CK_UART = 40 MHz
No.
Kbps
Actual
BRD
Deviation
Error Rate
1
2.4
2.4
16667
0.00%
2
9.6
9.6
4167
-0.01%
3
19.2
19.2
2083
0.02%
4
57.6
57.6
694
0.06%
5
115.2
115.3
347
0.06%
6
230.4
229.9
174
-0.22%
7
460.8
459.8
87
-0.22%
8
921.6
930.2
43
0.94%
9
2250
2222.2
18
-1.23%
10
3000
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