https://devzone.nordicsemi.com/f/nordic-q-a/14888/lfclk-the-interrupt-that-never-cameI&#39;m doing a more complex application than what I&#39;m showing here, but I&#39;ve reduced it to the minimum. I&#39;m initializing the RTC subsystem, creating a timer, and starting that timer. I have the S130 SoftDevice installed on my nRF51422 DK board (Nordicen-USTelligent Community 13Fri, 01 Jul 2016 18:03:47 GMThttps://devzone.nordicsemi.com/thread/56839?ContentTypeID=1Fri, 01 Jul 2016 18:03:47 GMT137ad170-7792-4731-bb38-c0d22fbe4515:aa92e819-808e-432f-884e-9322a263e42bMark W. Schumann<p>That does it. The new code has something like this, plus error checking and such:</p> <pre><code>sd_softdevice_enable(clock_source, assertion_handler); nrf_drv_clock_init(); </code></pre> <p>And now I am in fact getting timer interrupts. Thank you!</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/56838?ContentTypeID=1Fri, 01 Jul 2016 13:20:29 GMT137ad170-7792-4731-bb38-c0d22fbe4515:a067e679-6604-4832-8d0f-22d67917af51Paolo D<p>Maybe the problem is that the LFCLK clock isn&#39;t being started. Even if the RTC peripheral is set up properly it won&#39;t count until LFCLK is started. According to the documentation for APP_TIMER_INIT, if you aren&#39;t using the SoftDevice you have to start it manually. Just having the SoftDevice installed in flash isn&#39;t sufficient; you have to initialize it from the main function.</p><div style="clear:both;"></div>