We are planning on using the on-chip RTC module of the cpu.
We are now able to make it work and retain/make the clock running during power-off via external battery.
As with normal external RTC modules, they have a "Low voltage detected" function to judge whether power was cut off from the module. When low voltage is detected you cannot trust the RTC clock values so we reset to clock values to "0"
As we would like to use the CPU's internal RTC, is there a way to judge for "low voltage" or if RTC values can be "trusted"