control register
| TSEDGE | Time-stamp event active edge |
| REFCKON | RTC_REFIN reference clock detection enable (50 or 60 Hz) |
| BYPSHAD | Bypass the shadow registers |
| FMT | Hour format |
| ALRAE | Alarm A enable |
| TSE | timestamp enable |
| ALRAIE | Alarm A interrupt enable |
| TSIE | Time-stamp interrupt enable |
| ADD1H | Add 1 hour (summer time change) |
| SUB1H | Subtract 1 hour (winter time change) |
| BKP | Backup |
| COSEL | Calibration output selection |
| POL | Output polarity |
| OSEL | Output selection |
| COE | Calibration output enable |