AT32F421
Series Reference Manual
2022.11.11
Page 143
Rev 2.02
Figure 12-13 USART interrupt map diagram
USART
interrupt
TDBE
TDBEIEN
TDC
TDCIEN
CTSCF
CTSCFIEN
IDLEF
IDLEIEN
RDBFIEN
ROERR
RDBFIEN
RDBF
PERR
PERRIEN
BFF
BFIEN
FERR
NERR
ROERR
ERRIEN
DMAREN
12.11 I/O pin control
The following five interfaces are used for USART communication.
RX: Serial data input.
TX: Serial data output. In single-wire half-duplex and Smartcard mode, the TX pin is used as an I/O for
data transmission and reception.
CK: Transmitter clock output. The output CLK phase, polarity and frequency are programmable.
CTS: Transmitter input. Send enable signal in hardware flow control mode.
RTS: Receiver output. Send request signal in hardware flow control mode.
12.12 USART registers
These peripheral registers must be accessed by words (32 bits).
Table 12-5
USART register map and reset value
Register
Offset
Reset value
USART_STS
0x00
0x0000 00C0
USART_DT
0x04
0x0000 0000
USART_BAUDR
0x08
0x0000 0000
USART_CTRL1
0x0C
0x0000 0000
USART_CTRL2
0x10
0x0000 0000
USART_CTRL3
0x14
0x0000 0000
USART_GDIV
0x18
0x0000 0000