control register
| WCKSEL | Wakeup clock selection |
| TSEDGE | Time-stamp event active edge |
| REFCKON | Reference clock detection enable (50 or 60 Hz) |
| BYPSHAD | Bypass the shadow registers |
| FMT | Hour format |
| DCE | Coarse digital calibration enable |
| ALRAE | Alarm A enable |
| ALRBE | Alarm B enable |
| WUTE | Wakeup timer enable |
| TSE | Time stamp enable |
| ALRAIE | Alarm A interrupt enable |
| ALRBIE | Alarm B interrupt enable |
| WUTIE | Wakeup timer 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 |