https://devzone.nordicsemi.com/f/nordic-q-a/24437/uart-on-custom-boardhello we have custom board with Nrf52840. i already test the uart code on nrf52840 dk..every thing is working great. my custom board is connect to the nrf52840 dk with debug connector. debugging is working great on custom board. no connectionen-USTelligent Community 13Thu, 17 Aug 2017 14:08:03 GMThttps://devzone.nordicsemi.com/thread/96229?ContentTypeID=1Thu, 17 Aug 2017 14:08:03 GMT137ad170-7792-4731-bb38-c0d22fbe4515:27b57d72-6111-4d5f-b213-52a71f0313faAmbystomaLabs<p>The only thing available through the debug (SWD) connection is RTT. Just search in this blog for info on the Segger RTT implementation.</p> <p>For UART you need to have connected through at least 2 gpio for tx and rx. nRFgo Studio will present the uart as a virtual comm port through the USB connection for the dk board.</p> <p>The standard configuration for the UART is as below.</p> <pre><code>#define RX_PIN_NUMBER 8 #define TX_PIN_NUMBER 6 #define CTS_PIN_NUMBER 7 #define RTS_PIN_NUMBER 5 #define HWFC false </code></pre> <p>You can find this same info in the online documentation here: <a href="http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52/dita/nrf52/development/nrf52840_pdk/vir_com_port.html?cp=2_0_3_4_1#vir_com_port__table_ofy_cdj_sq">infocenter.nordicsemi.com/.../vir_com_port.html</a></p> <p>As an FYI, most people seem to provide for a UART connection on custom boards since a minimum of 3 wire serial (Tx, Rx, Gnd) is required for Bluetooth SIG certification if you are running bluetooth on your board.</p><div style="clear:both;"></div>