https://devzone.nordicsemi.com/f/nordic-q-a/25557/nrf51-dk---x2-oscillatorHello, I&#39;m using NRF51-DK (PCA10028) and I want to be sure if I&#39;m using the external 32KHz oscillator (X2). I&#39;m using SDK12.3.0. I&#39;m running the beacon example. In example, I&#39;m looking at decleration nrf_clock_lf_cfg_t clock_lf_cfg = NRF_CLOCK_LFCLKSRC;en-USTelligent Community 13Thu, 28 Sep 2017 20:41:50 GMThttps://devzone.nordicsemi.com/thread/100762?ContentTypeID=1Thu, 28 Sep 2017 20:41:50 GMT137ad170-7792-4731-bb38-c0d22fbe4515:76506dd6-9145-4d64-a05f-85dd5b0579e1RK<p>Yes that configuration is right to start the LF clock. If you want to confirm which LF clock is running why are you reading the HF clock register? That&#39;s not going to tell you anything (well it will, it will tell you what HF clock is running which is usually the internal RC until the crystal is needed). Read 0x40000418 and see what that says.</p><div style="clear:both;"></div>