Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32f0/STM32F0x0/RTC/TSDR#0x0
timestamp date register
Date units in BCD format
Date tens in BCD format
Month units in BCD format
Month tens in BCD format
Week day units
https://github.com/modm-io/cmsis-svd-stm32