AT32F425
Series Reference Manual
2022.03.30
Page 147
Ver 2.01
12
Universal synchronous/asynchronous
receiver/transmitter (USART)
12.1
USART introduction
The universal synchronous/asynchronous receiver/transmitter (USART) serves an interface for
communication by means of various configurations and peripherals with different data formats. It
supports asynchronous full-duplex and half-duplex as well as synchronous transfer. With a
programmable baud rate generator, USART offers up to 9 MBits/s of baud rate by setting the system
frequency and frequency divider, which is also convenient for users to configure the required
communication frequency.
In addition to standard NRZ asynchronous and synchronous receiver/transmitter communication
protocols, USART also supports widely-used serial communication protocols such as LIN (Local
Interconnection Network), IrDA (Infrared Data Association) SIRENDEC specification, Asynchronous
SmartCard protcoal defined in ISO7816-3 standard, and CTS/RTS (Clear To Send/Request To Send)
hardware flow operation.
It also allows mutli-processor communication, and supports silent mode waken up by idle frames or ID
matching to build up a USART network. Meanwhile, high-speed communication is possible by using
DMA.
Figure 12-1 USART block diagram
USART
interrupt control logic
USART control logic
TDBEIEN
TDCIEN
RDBFIEN
IDLEIEN
PERRIEN
CTSCFIEN
BFIEN
ERRIEN
Transmitter Logic
Receiver Logic
Mode select
UEN TEN PEN PSEL SBF STOPBN DBN1 DBN0
TSDT[4:0] TCDT[4:0] SCNACKEN
LINEN SCM EN CTSEN
RTSEN IRDAEN CLKEN
RS485EN DEP
UEN TEN PEN PSEL BFBN STOPBN DBN1 DBN0
SCNACKEN
USART STS
Wakeup
unit
WUM RM IDBN
ID[7:0]
GTVAL
DIV
CK control logic
GTPR
CLKEN
CLKPOL
CLKPHA
LBCP
Hardware flow
controller
IrDA
SIR
encoder/deco
der
USART Transmit/Receive Data control
Receive shift register
Transmit shift register
CK
Receiver
Logic
Communication baud rate
TX
RX
SW_RX
nRTS
nCTS
USART Baud Rate Producer
TEN
REN
DIV
USART_DT
To System
USART control logic
CTSEN RTSEN
IRDALP
IRDAEN DIV[7:0]
Full-
duplex/Half-
duplex
selector
SLBEN