This anomaly applies to Revision 2, build code CAAA-Bxx.
It was inherited from the previous SoC revision Revision 1.
Symptoms
RTC registers will not contain the correct/expected value if read.
Conditions
The RTC has been idle.
Consequences
RTC configuration cannot be determined by reading RTC registers.
Workaround
Execute the below code before you use RTC.
NRF_CLOCK->EVENTS_LFCLKSTARTED = 0;
NRF_CLOCK->TASKS_LFCLKSTART = 1;
while (NRF_CLOCK->EVENTS_LFCLKSTARTED == 0) {}
NRF_RTC0->TASKS_STOP = 0;