https://devzone.nordicsemi.com/f/nordic-q-a/6916/nrf51822-module-with-a-single-16mhz-crystalI have these nrf51822 modules, bought them from this company Wireless Tag , it&#39;s a chinese company I guess but I just noticed that the modules only have a single 16 MHZ oscillator hooked up (should have checked before). After reading part of the documentationen-USTelligent Community 13Wed, 06 May 2015 13:33:09 GMThttps://devzone.nordicsemi.com/thread/24394?ContentTypeID=1Wed, 06 May 2015 13:33:09 GMT137ad170-7792-4731-bb38-c0d22fbe4515:e3b36380-547e-4f3e-8ae3-47aac9514e95moenad<p>ok great than, thank you. I still have another question about programming it with openOCD, posted it right now, hopefully it would be great if you can help out.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/24393?ContentTypeID=1Wed, 06 May 2015 13:23:59 GMT137ad170-7792-4731-bb38-c0d22fbe4515:670c782b-6a59-4524-98c3-f746db2625adMartinBL<p>Hi!</p> <p>An external 32.768 Hz crystal is optional. You can also use the internal RC 32.768 Hz oscillator or synthesize the frequency from the 16 MHz clock. Read <a href="https://devzone.nordicsemi.com/question/953/what-low-frequency-clock-sources-can-i-use/">this great post</a> for more info.</p> <p>I am not sure if this is what you meant, but you do not need a 32 MHz clock. When designing a board you can chose <em>either</em> a 32 MHz <em>or</em> a 16 MHz crystal. And an external high frequency clock like this is mandatory, as opposed to the external low frequency clock.</p> <p>So you are all good. Your board should work fine as it is.</p><div style="clear:both;"></div>