https://devzone.nordicsemi.com/f/nordic-q-a/23212/adc-with-internal-pull-upThis is for the nRF51822. I have done some tests where I configure a pin as input with pull up enabled and then reconfigure the pin for an adc measurement with 1/3 prescaler with band gap reference. It looks like the pull up is enabled when theen-USTelligent Community 13Mon, 03 Jul 2017 14:32:24 GMThttps://devzone.nordicsemi.com/thread/91305?ContentTypeID=1Mon, 03 Jul 2017 14:32:24 GMT137ad170-7792-4731-bb38-c0d22fbe4515:32fdc010-fb94-4d6d-9ac1-63377fadbe21J&#248;rn<p>Hello Jimmie Johansson</p> <p>I have looked into this and you are correct that if the GPIO pull-up and pull-down resistors have been enabled, they are still connected when the ADC samples unless explicitly disabled before that. From what I have found this is the case for both the nRF51 and nRF52 series. It is not clearly stated in the documentation, and this has been reported.</p> <p>To ensure correct behavior you will need to take care and disable the pull-up and down resistors before starting the ADC sampling.</p> <p>I believe this will also apply when using the comparator.</p> <p>Best regards</p> <p>Jørn Frøysa</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/91304?ContentTypeID=1Mon, 03 Jul 2017 08:13:58 GMT137ad170-7792-4731-bb38-c0d22fbe4515:7bd1449a-90cb-4716-bbad-7e2cb55f6a7atesty<p>I can confirm exactly the same behaviour: nRF51422 QFAA F0 (3rd rev). Pull-up stays enabled and causes <strong>(un)desired voltage offset during ADC operation</strong>.</p><div style="clear:both;"></div>