https://devzone.nordicsemi.com/f/nordic-q-a/49334/32-768-khz-xtal-accuracyHi, We are in the HW verification stage of a product with an nRF52 series MCU. We were easily able to measure the 32MHz XTAL accuracy using the buffered output feature; however, we are having a hard time doing the same for the 32.768 kHz crystal.en-USTelligent Community 13Fri, 05 Jul 2019 09:29:39 GMThttps://devzone.nordicsemi.com/thread/196775?ContentTypeID=1Fri, 05 Jul 2019 09:29:39 GMT137ad170-7792-4731-bb38-c0d22fbe4515:e2722575-b759-48a8-919a-72bd714b49c3Kaja<p><span>Hi Eiad,&nbsp;</span><br /><br /><span>measuring the accuracy for the 32.768 kHz crystal is usually not necessary, it&#39;s usually enough calculating the load capacitors based on the crystal load capacitance, CL, and using the crystals accuracy.&nbsp;</span><br /><br /><span>Choosing load capacitors: Ccap = CL*2 - 4 pF.&nbsp;</span><br /><br /><span>&nbsp;There will always be a couple ppm inaccuracy, and the accuracy spec of the crystal will come on top of this. It should be fairly easy to experiment with with the configuration. Also, you might want to look into how accurate the 32.768 crystal actually is and take that into account.<br /><br />Do you generate&nbsp;an interrupt form the event? The measurement is probably not accurate, you could take out the signal via PPI/GPIOTE, and use a oscilloscope.<br /><br />Best regards,<br />Kaja<br /><br /><br /></span></p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/196774?ContentTypeID=1Fri, 05 Jul 2019 09:29:36 GMT137ad170-7792-4731-bb38-c0d22fbe4515:08baf078-7cd1-4988-9bee-9614d4fa2df3Kaja<p><span>Hi Eiad,&nbsp;</span><br /><br /><span>measuring the accuracy for the 32.768 kHz crystal is usually not necessary, it&#39;s usually enough calculating the load capacitors based on the crystal load capacitance, CL, and using the crystals accuracy.&nbsp;</span><br /><br /><span>Choosing load capacitors: Ccap = CL*2 - 4 pF.&nbsp;</span><br /><br /><span>&nbsp;There will always be a couple ppm inaccuracy, and the accuracy spec of the crystal will come on top of this. It should be fairly easy to experiment with with the configuration. Also, you might want to look into how accurate the 32.768 crystal actually is and take that into account.<br /><br />Do you generate&nbsp;an interrupt form the event? The measurement is probably not accurate, you could take out the signal via PPI/GPIOTE, and use a oscilloscope.<br /><br />Best regards,<br />Kaja<br /><br /><br /></span></p><div style="clear:both;"></div>