Universal Synchronous Asynchronous Receiver; Transmitter (Usart); Usart Introduction; Usart Main Features - ST STM32F205 series Reference Manual

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Universal synchronous asynchronous receiver

transmitter (USART)

This section applies to the whole STM32F20x and STM32F21x family, unless otherwise
specified.
24.1

USART 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 fractional baud rate generator.
It supports synchronous one-way communication and half-duplex single wire
communication. It also supports the LIN (local interconnection network), Smartcard Protocol
and IrDA (infrared data association) SIR ENDEC specifications, and modem operations
(CTS/RTS). It allows multiprocessor communication.
High speed data communication is possible by using the DMA for multibuffer configuration.
24.2

USART main features

•
Full duplex, asynchronous communications
•
NRZ standard format (Mark/Space)
•
Configurable oversampling method by 16 or by 8 to give flexibility between speed and
clock tolerance
•
Fractional baud rate generator systems
–
•
Programmable data word length (8 or 9 bits)
•
Configurable stop bits - support for 1 or 2 stop bits
•
LIN Master Synchronous Break send capability and LIN slave break detection
capability
–
• Transmitter clock output for synchronous transmission
•
IrDA SIR encoder decoder
–
•
Smartcard emulation capability
–
–
•
Single-wire half-duplex communication
•
Configurable multibuffer communication using DMA (direct memory access)
–
Universal synchronous asynchronous receiver transmitter (USART)
Common programmable transmit and receive baud rate of up to 7.5 Mbit/s when
the APB frequency is 60 MHz and oversampling is by 8
13-bit break generation and 10/11 bit break detection when USART is hardware
configured for LIN
Support for 3/16 bit duration for normal mode
The Smartcard interface supports the asynchronous protocol Smartcards as
defined in the ISO 7816-3 standards
0.5, 1.5 stop bits for Smartcard operation
Buffering of received/transmitted bytes in reserved SRAM using centralized DMA
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