Universal synchronous asynchronous receiver transmitter (USART) RM0090
966/1749 RM0090 Rev 18
• Transfer detection flags:
– Receive buffer full
– Transmit buffer empty
– End of transmission flags
• Parity control:
– Transmits parity bit
– Checks parity of received data byte
• Four error detection flags:
– Overrun error
– Noise detection
– Frame error
– Parity error
• Ten interrupt sources with flags:
– 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
• 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
th
bit), Idle line
30.3 USART functional description
The interface is externally connected to another device by three pins (see Figure 296). Any
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
pin is at high level. In single-wire and smartcard modes, this I/O is used to transmit and
receive the data (at USART level, data are then received on SW_RX).
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