Interrupt Flag Status and Clear
| Bit7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| ERROR | RXBRK | CTSIC | RXS | RXC | TXC | DRE | |
| AccessR/W | R/W | R/W | R/W | R | R/W | R | |
| Reset0 | 0 | 0 | 0 | 0 | 0 | 0 |
Error
This flag is cleared by writing '1' to it.
This bit is set when any error is detected. Errors that will set this flag have corresponding status flags in the STATUS register. Errors that will set this flag are COLL, ISF, BUFOVF, FERR, and PERR.Writing '0' to this bit has no effect.
Writing '1' to this bit will clear the flag.
Receive Break
This flag is cleared by writing '1' to it.
This flag is set when auto-baud is enabled (CTRLA.FORM) and a break character is received.
Writing '0' to this bit has no effect.
Writing '1' to this bit will clear the flag.
Clear to Send Input Change
This flag is cleared by writing a '1' to it.
This flag is set when a change is detected on the CTS pin.
Writing '0' to this bit has no effect.
Writing '1' to this bit will clear the flag.
Receive Start
This flag is cleared by writing '1' to it.
This flag is set when a start condition is detected on the RxD line and start-of-frame detection is enabled (CTRLB.SFDE is '1').
Writing '0' to this bit has no effect.
Writing '1' to this bit will clear the Receive Start interrupt flag.
Receive Complete
This flag is cleared by reading the Data register (DATA) or by disabling the receiver.
This flag is set when there are unread data in DATA.
Writing '0' to this bit has no effect.
Writing '1' to this bit has no effect.
Transmit Complete
This flag is cleared by writing '1' to it or by writing new data to DATA.
This flag is set when the entire frame in the transmit shift register has been shifted out and there are no new data in DATA.
Writing '0' to this bit has no effect.
Writing '1' to this bit will clear the flag.
Data Register Empty
This flag is cleared by writing new data to DATA.
This flag is set when DATA is empty and ready to be written.
Writing '0' to this bit has no effect.
Writing '1' to this bit has no effect.