https://devzone.nordicsemi.com/f/nordic-q-a/11177/adc-values-with-no-inputHello, I&#39;m trying to read voltage signals from a sensor using internal ADC and send them OTA. For now, my codes seems to work, but the only problem with my codes is it gives maximum ADC value (e.g. 0xFF at 8 bit resolution) when the analog input pinen-USTelligent Community 13Thu, 07 Jan 2016 13:29:50 GMThttps://devzone.nordicsemi.com/thread/41867?ContentTypeID=1Thu, 07 Jan 2016 13:29:50 GMT137ad170-7792-4731-bb38-c0d22fbe4515:e40bb4cb-b35d-4f5c-adcc-e3c03e595023awneil<p>Or an external pull-up in order to read &quot;high&quot; values on the ADC output when the sensor is not connected.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/41866?ContentTypeID=1Thu, 07 Jan 2016 13:24:03 GMT137ad170-7792-4731-bb38-c0d22fbe4515:2b201337-695a-4d3d-a945-1b172a190d3cStefan Birnir Sverrisson<p>Hi comkuk</p> <p>As awneil point out, the pin is floating when you do not have anything connected to it, and you could be reading whatever values with the ADC on a floating pin. When you have a pin configured as analog input pin, I do not thing you can define an internal pull for the pin. You could instead connect an external pull-down resistor to the pin, e.g. a 1Mohm resistor between the AIN pin and ground, in order to read zero values on the ADC output when the sensor is not connected.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/41865?ContentTypeID=1Thu, 07 Jan 2016 11:03:37 GMT137ad170-7792-4731-bb38-c0d22fbe4515:3fb97acc-92b3-403b-b13b-adee68cbc6aeawneil<p>An unconnected input could also float high ...</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/41864?ContentTypeID=1Thu, 07 Jan 2016 11:01:52 GMT137ad170-7792-4731-bb38-c0d22fbe4515:5e1c9384-e610-45db-8223-43d34342578dawneil<p>When the input is not connected, there will be <strong>noise</strong>.</p> <p>Presumably, your ADC is reading the noise.</p><div style="clear:both;"></div>