https://devzone.nordicsemi.com/f/nordic-q-a/32019/how-to-set-the-uart-connect-pinMy develop board is nrf51822 and the SDK version is 9.0 softdevice s130. Because the NRF51 board is build by the customer. So the UART connect pin is changed from {13,14,12,15} to {3,1,2,0}. Please kindly refs line 100 of examples/bsp/pca10028.h. Buten-USTelligent Community 13Tue, 13 Mar 2018 09:52:19 GMThttps://devzone.nordicsemi.com/thread/124112?ContentTypeID=1Tue, 13 Mar 2018 09:52:19 GMT137ad170-7792-4731-bb38-c0d22fbe4515:e1f34060-0aa1-45e9-8cc8-c09aa3c0c0c0Martin Lesund<p>Hi Sq,</p> <p>The nRF5x-devices have a flexible pin crossbar, so you are free to choose any available&nbsp;<a href="http://infocenter.nordicsemi.com/index.jsp?topic=%2Fcom.nordic.infocenter.nrf52810.ps%2Fgpio.html&amp;cp=2_2_0_5_7" target="_blank" rel="noopener noreferrer">GPIO&nbsp;</a>for digital peripherals, like the UART.</p> <p>&nbsp;</p> <p>From the <a href="http://infocenter.nordicsemi.com/pdf/nRF51822_PS_v3.3.pdf" target="_blank" rel="noopener noreferrer">product specification</a>:</p> <p><img src="https://devzone.nordicsemi.com/resized-image/__size/320x240/__key/support-attachments/beef5d1b77644c448dabff31668f3a47-5c31212f579847d88969a49d0643f275/pastedimage1520934691102v1.png" alt=" " /></p> <p>&nbsp;</p> <p>(<a href="https://devzone.nordicsemi.com/f/nordic-q-a/29928/pin-number-assignment/119023#119023" target="_blank" rel="noopener noreferrer">similar thread</a>)</p><div style="clear:both;"></div>