ST STM32L4+ Series Reference Manual page 1566

Real-time clock (RTC) applied to STM32L4Rxxx and STM32L4Sxxx only
46.6.2 RTC date register (RTC_DR)
The RTC_DR is the calendar date shadow register. This register must be written in
initialization mode only. Refer to
Reading the calendar on page
This register is write protected. The write access procedure is described in
write protection on page
Address offset: 0x04
Backup domain reset value: 0x0000 2101
System reset: 0x0000 2101 when BYPSHAD = 0. Not affected when BYPSHAD = 1.
31 30 29
Res. Res. Res. Res.
15 14 13
WDU[2:0]
rw rw rw
Bits 31:24 Reserved, must be kept at reset value.
Bits 23:20 YT[3:0]: Year tens in BCD format
Bits 19:16 YU[3:0]: Year units in BCD format
Bits 15:13 WDU[2:0]: Week day units
Bit 12 MT: Month tens in BCD format
Bits 11:8 MU[3:0]: Month units in BCD format
Bits 7:6 Reserved, must be kept at reset value.
Bits 5:4 DT[1:0]: Date tens in BCD format
Bits 3:0 DU[3:0]: Date units in BCD format
1566/2301
1553.
28 27 26 25
Res. Res. Res.
12 11 10 9
MT MU[3:0]
rw rw rw rw
000: forbidden
001: Monday
...
111: Sunday
Calendar initialization and configuration on page 1554
1555.
24 23 22
Res. YT[3:0]
rw rw
8 7 6
Res. Res.
rw
RM0432 Rev 6
RTC register
21 20 19 18
YU[3:0]
rw rw rw rw
5 4 3 2
DT[1:0] DU[3:0]
rw rw rw rw
RM0432
and
17 16
rw rw
1 0
rw rw