Function Descriptions; Serial Data Format; Figure 107. Usart Serial Data Format - Holtek HT32F52220 User Manual

32-Bit Arm ® Cortex ® -M0+ MCU
HT32F52220/HT32F52230

Function Descriptions

Serial Data Format

The USART module performs a parallel-to-serial conversion on data that is written to the transmit
FIFO registers and then sends the data with the following format: Start bit, 7 ~ 9 LSB first data
bits, optional Parity bit and finally 1 ~ 2 Stop bits. The Start bit has the opposite polarity of the
data line idle state. The Stop bit is the same as the data line idle state and provides a delay before
the next start situation. The both Start and Stop bits are used for data synchronization during the
asynchronous data transmission.
The USART module also performs a serial-to-parallel conversion on the data that is read from the
receive FIFO registers. It will first check the Parity bit and will then look for a Stop bit. If the Stop
bit is not found, the USART module will consider the entire word transmission to have failed and
respond with a Framing Error.
Start Bit Bit0 Bit1
Start Bit Bit0 Bit1
Start Bit Bit0 Bit1
Start Bit Bit0 Bit1
Start Bit Bit0 Bit1

Figure 107. USART Serial Data Format

Rev. 1.10
7-Bit Data Format
(WLS[1:0]=0x00, PBE=0)
Bit2 Bit3 Bit4 Bit5
8-Bit Data Format
(WLS[1:0]=0x01, PBE=0)
Bit2 Bit3 Bit4 Bit5
(WLS[1:0]=0x00, PBE=1)
Bit2 Bit3 Bit4 Bit5
9-Bit Data Format
(WLS[1:0]=0x10, PBE=0)
Bit2 Bit3 Bit4 Bit5
(WLS[1:0]=0x01, PBE=1)
Bit2 Bit3 Bit4 Bit5
328 of 366
Next Start
Bit6
Stop Bit
Bit
Next Start
Bit6 Bit7 Stop Bit
Bit
Next Start
Bit6 Parity Bit Stop Bit
Bit
Bit6 Bit7 Bit8 Stop Bit
Bit6 Bit7 Parity Bit Stop Bit
November 09, 2018
Next Start
Bit
Next Start
Bit