interrupt and status register
| SYNCOKF | SYNC event OK flag |
| SYNCWARNF | SYNC warning flag |
| ERRF | Error flag |
| ESYNCF | Expected SYNC flag |
| SYNCERR | SYNC error |
| SYNCMISS | SYNC missed |
| TRIMOVF | Trimming overflow or underflow |
| FEDIR | Frequency error direction |
| FECAP | Frequency error capture |