https://devzone.nordicsemi.com/f/nordic-q-a/17672/gpio-controlHi. I&#39;m using PCA10040. I&#39;m trying to control GPIO. But I can&#39;t control PIN 09, 10. Let me show you my source code. int main(void) { /* Configure LED-pins as outputs. */ for(int i=5;i&lt;26;i++) { nrf_gpio_pin_set(i); nrf_gpio_cfg_outputen-USTelligent Community 13Fri, 11 Nov 2016 09:44:09 GMThttps://devzone.nordicsemi.com/thread/67985?ContentTypeID=1Fri, 11 Nov 2016 09:44:09 GMT137ad170-7792-4731-bb38-c0d22fbe4515:b450a00e-0ace-4123-b284-c425d82a4f73MartinBL<p>Did you try both of Bjørn&#39;s suggestions <a href="https://devzone.nordicsemi.com/question/96013/how-to-enable-p009-and-p010-as-gpio-pins-on-the-nrf52-instead-of-nfc-pins/">here</a>?</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/67984?ContentTypeID=1Fri, 11 Nov 2016 08:45:42 GMT137ad170-7792-4731-bb38-c0d22fbe4515:513bf015-fc9c-4123-a6b3-106da971563eroger.k<p>Thank you for your reply. How can I clear the NFCPINS UICR register? Can you give me a source code? I hope your reply.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/67983?ContentTypeID=1Fri, 11 Nov 2016 08:43:27 GMT137ad170-7792-4731-bb38-c0d22fbe4515:2d48adab-c3db-49f4-934e-27fd54becc77MartinBL<p>Hi,</p> <p>Those are the <a href="http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52832.ps.v1.1/nfc.html?cp=2_2_0_41_1#concept_fq1_1bk_1s">pins used for the NFC</a>. You need to <a href="https://devzone.nordicsemi.com/question/96013/how-to-enable-p009-and-p010-as-gpio-pins-on-the-nrf52-instead-of-nfc-pins/">clear the first</a> bit in the <a href="http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52832.ps.v1.1/uicr.html?cp=2_2_0_13_0_62#register.NFCPINS">NFCPINS UICR</a> register in order to use them as GPIO pins.</p><div style="clear:both;"></div>