before setting NRF_POWER -> SYSTEMOFF = 1, I chose a switch button and an accelerometer as external wake-up sources.
both of the wake-up sources can wake up the chip in short time (about 15 mins)
but after 15 mins or more, the chip can not be waken up
What may have caused this phenomenon?
Is there something else I have to do before setting NRF_POWER -> SYSTEMOFF = 1
