Table 1. Available Interrupt Vectors and Sources
Name Vector Description Conditions
RXC Receive Complete interrupt
  • There is unread data in the receive buffer (RXCIE)
  • Receive of Start-of-Frame detected (RXSIE)
  • Auto-Baud Error/ISFIF flag set (ABEIE)
DRE Data Register Empty interrupt The transmit buffer is empty/ready to receive new data (DREIE)
TXC Transmit Complete interrupt The entire frame in the transmit shift register has been shifted out and there are no new data in the transmit buffer (TXCIE)

When an interrupt condition occurs, the corresponding interrupt flag is set in the STATUS (USARTn.STATUS) register.

An interrupt source is enabled or disabled by writing to the corresponding bit in the Control A (USARTn.CTRLA) register.

An interrupt request is generated when the corresponding interrupt source is enabled, and the Interrupt flag is set. The interrupt request remains active until the Interrupt flag is cleared. See the USARTn.STATUS register for details on how to clear Interrupt flags.