Table 1. Available Interrupt Vectors and Sources
Offset Name Vector Description Conditions
0x00 RXC Receive Complete interrupt
  • There are unread data in the receive buffer (RXCIE)
  • Receive of Start-of-Frame detected (RXSIE)
  • Auto-Baud Error/ISFIF flag set (ABEIE)
0x02 DRE Data Register Empty interrupt The transmit buffer is empty/ready to receive new data (DREIE).
0x04 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 register (USART.STATUS).

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

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 USART.STATUS register for details on how to clear Interrupt Flags.