Usart Functional Description - ST STM32F100 Series Reference Manual

Universal synchronous asynchronous receiver transmitter (USART)
–
–
•
Single-wire half-duplex communication
•
Configurable multibuffer communication using DMA (direct memory access)
–
•
Separate enable bits for transmitter and receiver
•
Transfer detection flags:
–
–
–
•
Parity control:
–
–
•
Four error detection flags:
–
–
–
–
•
Ten interrupt sources with flags:
–
–
–
–
–
–
–
–
–
–
• Multiprocessor communication - enter into mute mode if address match does not occur
•
Wake up from mute mode (by idle line detection or address mark detection)
• Two receiver wakeup modes: Address bit (MSB, 9
23.3

USART functional description

The interface is externally connected to another device by three pins (see
USART bidirectional communication requires a minimum of two pins: Receive Data In (RX)
and Transmit Data Out (TX):
RX: Receive Data Input is the serial data input. Oversampling techniques are used for data
recovery by discriminating between valid incoming data and noise.
TX: Transmit Data Output. When the transmitter is disabled, the output pin returns to its I/O
port configuration. When the transmitter is enabled and nothing is to be transmitted, the TX
600/709
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
Receive buffer full
Transmit buffer empty
End of transmission flags
Transmits parity bit
Checks parity of received data byte
Overrun error
Noise detection
Frame error
Parity error
CTS changes
LIN break detection
Transmit data register empty
Transmission complete
Receive data register full
Idle line received
Overrun error
Framing error
Noise error
Parity error
RM0041 Rev 6
th
bit), Idle line
Figure
RM0041
243). Any