Yet another ADC question

[Valer_I]

Hello, My device is based on nRF51822 SD110 v8.0. Softdevice is enabled, but no BT functionality used. I measure 2 different voltages with ADC each second with two channels. It works, but after each 4096 seconds it measure incorrect (lowered) values for next 4096 seconds. And latches back to correct measurement...
(Grid divide by 4096s). Device is powered from line adaptor and supply voltage is constant. The only thing I found that could be participal is NRF_RTC1 timer that I use to count seconds.

 NRF_RTC1->CC[1] =     4096;
 NRF_RTC1->PRESCALER   = (8-1);

and take to count seconds - NRF_RTC1->COUNTER/4096

Any idea?

[Ole Bauck]

Since it looks like this is connected to the RTC I have a few question about that:

With prescaler equal to 7 the RTC will overflow after 4096 seconds. Do you do anything in your code when the RTC overflows or when the RTC counter is equal to compare value CC[1]?