ST STM32L4 5 Series Reference Manual page 1302

Universal synchronous asynchronous receiver transmitter (USART)
40 Universal synchronous asynchronous receiver
transmitter (USART)
40.1 Introduction
The universal synchronous asynchronous receiver transmitter (USART) offers a flexible
means of Full-duplex data exchange with external equipment requiring an industry standard
NRZ asynchronous serial data format. The USART offers a very wide range of baud rates
using a programmable baud rate generator.
It supports synchronous one-way communication and Half-duplex Single-wire
communication, as well as multiprocessor communications. It also supports the LIN (Local
Interconnect Network), Smartcard protocol and IrDA (Infrared Data Association) SIR
ENDEC specifications and Modem operations (CTS/RTS).
High speed data communication is possible by using the DMA (direct memory access) for
multibuffer configuration.
40.2 USART main features
•
Full-duplex asynchronous communications
•
NRZ standard format (mark/space)
•
Configurable oversampling method by 16 or 8 to give flexibility between speed and
clock tolerance
•
A common programmable transmit and receive baud rate of up to 10 Mbit/s when the
clock frequency is 80 MHz and oversampling is by 8
•
Dual clock domain allowing:
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• Auto baud rate detection
•
Programmable data word length (7, 8 or 9 bits)
• Programmable data order with MSB-first or LSB-first shifting
•
Configurable stop bits (1 or 2 stop bits)
• Synchronous mode and clock output for synchronous communications
•
Single-wire Half-duplex communications
• Continuous communications using DMA
•
Received/transmitted bytes are buffered in reserved SRAM using centralized DMA
• Separate enable bits for transmitter and receiver
•
Separate signal polarity control for transmission and reception
• Swappable Tx/Rx pin configuration
•
Hardware flow control for modem and RS-485 transceiver
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USART functionality and wakeup from Stop mode
Convenient baud rate programming independent from the PCLK reprogramming
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RM0351