GD32W51x User Manual
589
18.
Universal
synchronous/asynchronous
receiver
/transmitter (USART)
18.1.
Overview
The Universal Synchronous/Asynchronous Receiver/Transmitter (USART) provides a flexible
serial data exchange interface. Data frames can be transferred in full duplex or half duplex
mode, synchronously or asynchronously through this interface. A programmable baud rate
generator divides the UCLK (PCLK, CK_SYS, LXTAL, IRC16M) to produces a dedicated wide
range baudrate clock for the USART transmitter and receiver.
Besides the standard asynchronous receiver and transmitter mode, the USART implements
several other types of serial data exchange modes, such as IrDA (infrared data association)
SIR mode, smartcard mode, LIN (local interconnection network) mode, half-duplex mode and
synchronous mode. It also supports multiprocessor communication mode, and hardware flow
control protocol (CTS/RTS). The data frame can be transferred from LSB or MSB bit. The
polarity of the TX/RX pins can be configured independently and flexibly.
All USARTs support DMA function for high-speed data communication.
18.2.
Characteristics
NRZ standard format
Asynchronous, full duplex communication
Half duplex single wire communications
Receive FIFO function
Dual clock domain:
–
Asynchronous PCLK and USART clock independent of PCLK
–
Baud rate programming independent from the UCLK reprogramming
Programmable baud-rate generator allowing speed up to 11.25 MBits/s when the clock
frequency is 90 MHz and oversampling is by 8
Fully programmable serial interface characteristics:
–
A data word (8 or 9 bits) LSB or MSB first
–
Even, odd or no-parity bit generation/detection
–
0.5, 1, 1.5 or 2 stop bit generation
Swappable Tx/Rx pin
Configurable data polarity
Auto baud rate detection
Hardware Modem operations (CTS/RTS) and RS485 drive enable
Configurable multibuffer communication using centralized DMA
Separate enable bits for Transmitter and Receiver