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Rev. 1.00
443 of 486
July 31, 2018
32-Bit Arm
®
Cortex
®
-M0+ MCU
HT32F50231/HT32F50241
21 Universal Synchronous
Asynchronous Receiver T
ransmitter (USART)
Table 50. Baud Rate Deviation Error Calculation – CK_USART = 20 MHz
Baud Rate
CK_USART = 20 MHz
No.
Kbps
Actual
BRD
Deviation Error Rate
1
2.4
2.4
8333
0.00%
2
9.6
9.6
2083
0.02%
3
19.2
19.2
1042
-0.03%
4
57.6
57.6
347
0.06%
5
115.2
114.9
174
-0.22%
6
230.4
229.9
87
-0.22%
7
460.8
465.1
43
0.94%
8
921.6
909.1
22
-1.36%
9
1250
1250
16
0%
Table 51. Baud Rate Deviation Error Calculation – CK_USART = 10 MHz
Baud Rate
CK_USART = 10 MHz
No.
Kbps
Actual
BRD
Deviation Error Rate
1
2.4
2.4
4167
-0.01%
2
9.6
9.6
1042
-0.03%
3
19.2
19.2
521
-0.03%
4
57.6
57.6
174
-0.22%
5
115.2
114.9
87
-0.22%
6
230.4
232.6
43
0.94%
7
460.8
454.5
22
-1.36%
8
625
625
16
0%
Hardware Flow Control
The USART supports the hardware flow control function which is enabled by setting the HFCEN
bit in the USRCR register to 1. It is possible to control the serial data flow between 2 USART
devices by using the CTS input and the RTS output. The Figure
165 shows the connection diagram
in this mode. The hardware flow control function is categorized into two types. One is the RTS
flow control function and the other is the CTS flow control function.
TX
RX
USART 1
Transmitter
Receiver
USART 2
Transmitter
Receiver
RX
RTS
CTS
RTS
CTS
TX
Figure 165. Hardware Flow Control between 2 USARTs