https://devzone.nordicsemi.com/f/nordic-q-a/2846/calibration-of-hfclk-in-firmwareHi, I am using the nRF51822 with an external 16MHz crystal. I was curious if there is any way to tune/calibrate the system clock that is derived from this crystal. The purpose of this calibration is to make sure the RF frequency is as accurate as possibleen-USTelligent Community 13Thu, 19 Jun 2014 12:40:13 GMThttps://devzone.nordicsemi.com/thread/10855?ContentTypeID=1Thu, 19 Jun 2014 12:40:13 GMT137ad170-7792-4731-bb38-c0d22fbe4515:64e6e202-137e-4e2b-9762-46076e781072H&#229;kon Alseth<p>No, there is no way of calibrating the HFCLK. The external 16 MHz is used to generate the 2.4 GHz, so as long as your external crystal is within our specification when it comes to frequency and tolerance, you should be fine.</p><div style="clear:both;"></div>