https://devzone.nordicsemi.com/f/nordic-q-a/9819/rtc1-problem-of-accuracyHello, I&#39;m trying to use the APP_TIMER API to have tempo, but I&#39;ve noticed a problem of accuracy when using the RTC1. I use 0 as prescaler, so the RTC1 runs at 32768Hz. But when I want a tempo of 32768 ticks (in order to have 1 second of tempo),en-USTelligent Community 13Tue, 20 Oct 2015 15:23:21 GMThttps://devzone.nordicsemi.com/thread/36389?ContentTypeID=1Tue, 20 Oct 2015 15:23:21 GMT137ad170-7792-4731-bb38-c0d22fbe4515:7b5c5dbb-6ee6-4223-b0b7-8480165192ccTheRaven<p>I haven&#39;t selected a LFCLK. After selecting the XTAL LFCLK, 32768 represents exactly 1.000s on my osxilloscope, so it seems that APP_TIMER uses the internal clock by default !</p> <p>Thank you very much for helping me to solve my problem !!</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/36388?ContentTypeID=1Tue, 20 Oct 2015 14:56:52 GMT137ad170-7792-4731-bb38-c0d22fbe4515:b1f129cd-9c23-4d98-bb47-45078186df67Susheel Nuguru<p>Interesting .... Your code looks correct, RTC1 uses LFCLK, which LFCLK have you selected? I see that the code starts the LFCLK but cant see which one. I am not sure if APP_TIMER selects any clock by default (and i do not have the code handy to verify) If you (or app_timer) have selected internal RC LFCLK, then the error seems to be inline with this clock jitter. Try to select the XTAL LFCLK explicitly and see if there is any improvement</p><div style="clear:both;"></div>