RTC_ALRMAR register
| SU | Second units in BCD format. |
| ST | Second tens in BCD format. |
| MSK1 | Alarm A seconds mask 0: Alarm A set if the seconds match 1: Seconds dont care in Alarm A comparison |
| MNU | Minute units in BCD format. |
| MNT | Minute tens in BCD format. |
| MSK2 | Alarm A minutes mask 0: Alarm A set if the minutes match 1: Minutes dont care in Alarm A comparison |
| HU | Hour units in BCD format. |
| HT | Hour tens in BCD format. |
| PM | AM/PM notation 0: AM or 24-hour format 1: PM |
| MSK3 | Alarm A hours mask 0: Alarm A set if the hours match 1: Hours dont care in Alarm A comparison |
| DU | Date units or day in BCD format. |
| DT | Date tens in BCD format. |
| WDSEL | Week day selection 0: DU[3:0] represents the date units 1: DU[3:0] represents the week day. DT[1:0] is dont care. |
| MSK4 | Alarm A date mask 0: Alarm A set if the date/day match 1: Date/day dont care in Alarm A comparison |