https://devzone.nordicsemi.com/f/nordic-q-a/17022/rtc-system-time-inaccuracyI have a 1 second app_timer running which increments a 1 second variable used as unix time. We have a 32Khz Xtal, etc, which should result in good accuracy. I have noticed drift of several seconds per day over several devices just sitting on a shelfen-USTelligent Community 13Thu, 13 Oct 2016 00:04:09 GMThttps://devzone.nordicsemi.com/thread/65305?ContentTypeID=1Thu, 13 Oct 2016 00:04:09 GMT137ad170-7792-4731-bb38-c0d22fbe4515:182317b9-9def-4162-a297-7ea95d98db4eRK<p>Before overcomplicating the code you should understand why it is the timer isn&#39;t accurate. Are you getting too long intervals between ticks (or too short) or are you missing ticks now and again? Do you have the timer set up to be a repeating timer, or are you rescheduling the next 100ms after the expiration of the previous one?</p> <p>Nor do you need to use app_timer at all if you just want something as simple as a clock. You don&#39;t say whether you&#39;re using nRF51 or nRF52, the latter has an extra RTC you could use with a large prescalar to count slowly, then all you have to do is deal with overflow and you have an accurate clock.</p><div style="clear:both;"></div>