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Rev. 1.00
469 of 576
January 28, 2022
32-Bit Arm
®
Cortex
®
-M0+ MCU
HT32F54231/HT32F54241/HT32F54243/HT32F54253
22 Universal Synchronous
Asynchronous Receiver T
ransmitter (USART)
22 Universal Synchronous
Asynchronous Receiver T
ransmitter (USART)
Features
▆
Supports both asynchronous and clocked synchronous serial communication modes
▆
Full Duplex Communication Capability
▆
Programmable baud rate clock frequency up to (f
PLCK
/16) MHz for asynchronous mode and
(f
PLCK
/8) MHz for synchronous mode
▆
IrDA SIR encoder and decoder
●
Support normal 3/16 bit duration and low-power (1.41 ~ 2.23 μs) durations
▆
Supports RS485 mode with output enable
▆
Auto hardware flow control mode – RTS, CTS
▆
Fully programmable serial communication functions including:
●
Word length: 7, 8 or 9-bit character
●
Parity: Even, odd, or no-parity bit generation and detection
●
Stop bit: 1 or 2 stop bits generation
●
Bit order: LSB-first or MSB-first transfer
▆
Error detection: Parity, overrun and frame error
▆
FIFO:
●
Receive FIFO: 8-level
●
Transmit FIFO: 8-level
▆
Supports PDMA Interface, the PDMA related describes are only available for the HT32F54243/
HT32F54253 devices
Functional 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/MSB 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. Both the 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 as failed and
respond with a Framing Error.