I have a question about the RTC on STM43F429. I have a board that manages the RTC date and Time with a battery backup. After some test I have this problem: after a reset , when I try to read the RTC time for the first time, the RTC seems stopped (I see hh:mm:ss stipped) but if I look at the internal RTC register (with debugger) all is OK... so I cant read the current time. To solve this I have to read the date before and then I can read the time and the RTC is running correctly.. I don't understand why I have to read the date before to read the time. Can someone explay this? Thanks
You need wait when data from RTC will be synchronised with their shadow registers, it is every two RTC clocks, and can be checked with RTC_ISR.RSF (Registers Synchronisation Flag).
More info is in Reference manual section 26.3.2 Real-time clock and calendar.