https://devzone.nordicsemi.com/f/nordic-q-a/27445/internal-crystal-settingsHello All, I am working on Raytac module based on nrf51822 with ble_app_uart code. I can see on module there is no external crystal , my module is not able advertise, i can see nothing in Nordic Uart APP. my clock setting are as below. #ifdef S210en-USTelligent Community 13Tue, 21 Nov 2017 16:34:30 GMThttps://devzone.nordicsemi.com/thread/108391?ContentTypeID=1Tue, 21 Nov 2017 16:34:30 GMT137ad170-7792-4731-bb38-c0d22fbe4515:f6fe8023-3fbd-437d-a58b-17c427a0e176AmbystomaLabs<p>Just so you understand, there is no &quot;internal crystal&quot;. It is an internal RC oscillator. The oscillator is calibrated periodically against the 32MHz crystal. The calibration intervals and temp parameters are rc_ctiv and rc_temp_ctiv in below info. You will see an increase of about 8 uA (approx based on my memory) average current consumption between the RC circuit and the periodic calibration routine which uses the processor.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/108392?ContentTypeID=1Tue, 21 Nov 2017 10:09:54 GMT137ad170-7792-4731-bb38-c0d22fbe4515:71442ed0-f9ad-4463-bd4b-2ae1e7a84606max<pre><code>// Low frequency clock source to be used by the SoftDevice #define NRF_CLOCK_LFCLKSRC {.source = NRF_CLOCK_LF_SRC_RC, \ .rc_ctiv = 16, \ .rc_temp_ctiv = 2, \ .xtal_accuracy = NRF_CLOCK_LF_XTAL_ACCURACY_20_PPM} </code></pre><div style="clear:both;"></div>