10-04-2012 03:34 PM
For the RTC on my ZC702 board, I got:
rtc-pcf8563 5-0051: low voltage detected, date/time is not reliable.
rtc-pcf8563 5-0051: retrieved date/time is not valid.
What does that mean? Change battery? Or something else I need to do?
10-12-2012 02:34 PM
Thanks a lot, John. Really appreciate your help.
Just let you know that I got "low voltage dected", and I got this message for both of my boards. In theory, it shouldn't run out of battery.
10-15-2012 03:30 PM
10-24-2012 07:18 AM
For RTC is used secondary battery B2 which is not mounted on PCB.
Don't use standart Lithium coins, because this B2 battey has charging circuit!!!
01-21-2015 05:32 PM
For others who find this thread:
This warning message occurs when the VL flag in the RTC's SECONDS register is set. This flag gets set when VDD falls below a certain threshold (like low battery). It stays set until cleared by writing a zero to bit 7 of the SECONDS register (offset 0x02).
After updating the date and time I no longer receive this warning and the date holds through power off.
The RTC chip has an auto incrementing address, so you can write all date and time fields in one go.