In light sleep and deep sleep, RTC clock is used for timekeeping. This is either the internal 150kHz oscillator, or external 32kHz XTAL. The internal 150kHz oscillator is +/-5%. Thank you for the fast reply. Thats really bad news. :-( So without an external xtal, sleep is unusable for any serious d...

Hi,
I need to keep track of time during light sleep. Since the CPU is off I assume none of the timers will work. Is there another way to keep track of time during light sleep? Can RTC be used somehow?

Thanks