https://devzone.nordicsemi.com/f/nordic-q-a/1880/gpio-pull-upin my pca10001 board, once i made led pin 18 and 19 pin as internal pull up. led is not on,and i probe it also but not high. here my config in blinky example. NRF_GPIO-&gt;PIN_CNF[18] = (GPIO_PIN_CNF_SENSE_Disabled &lt;&lt; GPIO_PIN_CNF_SENSE_Pos)en-USTelligent Community 13Thu, 13 Mar 2014 12:59:10 GMThttps://devzone.nordicsemi.com/thread/8115?ContentTypeID=1Thu, 13 Mar 2014 12:59:10 GMT137ad170-7792-4731-bb38-c0d22fbe4515:949136d5-d176-4cdf-b2aa-db1750f3379cH&#229;kon Alseth<p>Hi,</p> <p>Pull resistors are only valid in input mode. connecting them while in output mode will not work. Please set the desired output value using OUT/OUTSET/OUTCLR registers.</p> <p>Best regards Håkon</p><div style="clear:both;"></div>