https://devzone.nordicsemi.com/f/nordic-q-a/17706/uart-communicationHi, all. I tested ble_app_uart in example directory by PCA10040 board. The ble_app_uart includes &quot;printf(&quot;\r\nUART Start!\r\n&quot;);&quot; and &quot;UART Start!&quot; cames out on the putty connected with PCA10040 USB UART port. Good~ Then I ported the ble_app_uarten-USTelligent Community 13Wed, 25 Jan 2017 13:24:43 GMThttps://devzone.nordicsemi.com/thread/68121?ContentTypeID=1Wed, 25 Jan 2017 13:24:43 GMT137ad170-7792-4731-bb38-c0d22fbe4515:7dd03a00-2929-4eda-9360-b710c076b1d1Stian R&#248;ed Hafskjold<p>It&#39;s not easy to say what can be wrong here. I guess you have to narrow the problem down somehow, using a logic analyzer or a oscilloscope and see if you get the expected data on the lines. If the data out from the nRF5 chip is correct, as it probably is since it is working with the DK, I guess you have to go through the USB-UART converter datasheet to see if there&#39;s anything you have missed.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/68119?ContentTypeID=1Tue, 15 Nov 2016 15:50:58 GMT137ad170-7792-4731-bb38-c0d22fbe4515:e5538c2d-2130-431a-87b4-dade010c995eAlex<p>Do you see any signal on TX line with oscilloscope? Is the COM port speed of the convertor the same as you are using on PCA10040 board?</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/68118?ContentTypeID=1Mon, 14 Nov 2016 23:32:32 GMT137ad170-7792-4731-bb38-c0d22fbe4515:e02c7bf0-c91b-4649-907f-be246b903b78paul0208<p>COM port number is COM48. I use tera-term instead of putty. And I have double checked the connection swap.</p> <p>Are there any point I missed?</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/68120?ContentTypeID=1Mon, 14 Nov 2016 10:05:38 GMT137ad170-7792-4731-bb38-c0d22fbe4515:e22e392f-a1db-416b-a54a-868e49aff51eAlex<p>Silly questions but... have you used convertor&#39;s COM port number in putty? Have you connected RX and TX correctly, not swapped?</p><div style="clear:both;"></div>