
Rev. 1.00
442 of 486
July 31, 2018
32-Bit Arm
®
Cortex
®
-M0+ MCU
HT32F50231/HT32F50241
21 Universal Synchronous
Asynchronous Receiver T
ransmitter (USART)
21 Universal Synchronous
Asynchronous Receiver T
ransmitter (USART)
Start Bit
Start Bit
Stop Bit
Stop Bit
Next Start
Bit
Next Start
Bit
Bit0
Bit1
Bit2
Bit3
Bit4
Bit5
Bit6
Bit0
Bit1
Bit2
Bit3
Bit4
Bit5
Bit6
Bit7
Bit8
8-Bit Data Format
9-Bit Data Format
Parity Bit
Start Bit
Bit0
Bit1
Bit2
Bit3
Bit4
Bit5
Bit6
7-Bit Data Format
Stop Bit
Next Start
Bit
Start Bit
Stop Bit
Next Start
Bit
Bit0
Bit1
Bit2
Bit3
Bit4
Bit5
Bit6
Bit7
Start Bit
Stop Bit
Next Start
Bit
Bit0
Bit1
Bit2
Bit3
Bit4
Bit5
Bit6
Bit7 Parity Bit
(WLS[1:0]=b00, PBE=0)
(WLS[1:0]=b01, PBE=0)
(WLS[1:0]=b00, PBE=1)
(WLS[1:0]=b10, PBE=0)
(WLS[1:0]=b01, PBE=1)
Figure 163. USART Serial Data Format
Baud Rate Generation
The baud rate for the USART receiver and transmitter are both set with the same values. The baud
rate divisor, BRD, has the following relationship with the USART clock which is known as CK_
USART.
Baud Rate Clock = CK_USART / BRD
Where CK_USART clock is the APB clock connected to the USART while the BRD range is from
16 to 65535 for asynchronous mode and 8 to 65535 for synchronous mode.
CK_USART
BRD =18
Reference
Divisor Clock
Start Bit
Bit0
Bit1
Bit2
Bit3
Bit4
Bitn
Parity Bit
Stop Bit
Next Start
Bit
n = 6 ~ 8
Figure 164. USART Clock CK_USART and Data Frame Timing