Reception Interrupt Control Register
| OVF | Counter overflow detection bit |
| EOM | EOM detection bit |
| ACK | ACK: ACK detection bit |
| ST | Start bit detection bit |
| OVFSEL | Counter overflow detection condition setting bit |
| OVFIE | Counter overflow interrupt enable bit |
| ACKIE | ACK interrupt enable bit |
| STIE | Start bit interrupt enable bit |