When using a supercapacitor instead of a battery, the flag called BLF is in 1 logical, which is used to determine if the battery is no longer useful but in this case I think it may not help.
Something that I have determined is that the time and date information of the RTC is out of range when the capacitor has been discharged and its voltage has not been sufficient to retrieve the information.
For example, minutes have a value greater than 0x59.
I think that checking all time and date registers may be an option to determine that the RTC needs to be matched but at the same time I think it is a cumbersome solution.
Is there a way to check faster or more effectively that time and date data are corrupted?
Any ideas or comments are welcome.