https://devzone.nordicsemi.com/f/nordic-q-a/57220/nrf52840---sdk16---ble-echoHi I tried modifying the ble_app_uart_pca10056_s140 example as follows (nus_data_handler method modified only) such that it echoes the data back sent from the phone: I expect the nRF52840 to echo back the example array which currently contains &quot;ECHOen-USTelligent Community 13Mon, 03 Feb 2020 08:09:55 GMThttps://devzone.nordicsemi.com/thread/232245?ContentTypeID=1Mon, 03 Feb 2020 08:09:55 GMT137ad170-7792-4731-bb38-c0d22fbe4515:4c8f5271-e3c6-4b61-b176-4af8faa49c3cLuke Galea<p>Oh ok then, It was kind of misleading in the documentation then because it mentions only the TX sent. Thank you for confirming.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/232243?ContentTypeID=1Mon, 03 Feb 2020 08:07:49 GMT137ad170-7792-4731-bb38-c0d22fbe4515:c5466184-eea7-4131-9982-582411b83ba3Sigurd<p>It&#39;s the length in bytes to be written, and length in bytes written after return. I.e setting it to 0, nothing will be sent.</p> <div> <div></div> </div><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/232238?ContentTypeID=1Mon, 03 Feb 2020 07:48:44 GMT137ad170-7792-4731-bb38-c0d22fbe4515:da33e701-ace4-4d9e-b6c3-9e470c67255cLuke Galea<p>Hi Sigurd, I thought that the length_example is the variable to which the amount of characters sent will be written to? Or was I mistaken? Sending data from the phone to the nRF52840 is working fine.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/232234?ContentTypeID=1Mon, 03 Feb 2020 07:42:21 GMT137ad170-7792-4731-bb38-c0d22fbe4515:fb16a7e3-12cd-4391-bcbd-ce6901650df3Sigurd<p>Hi,</p> <p>You are setting length_example to 0, so nothing will be sent.<br />Also, remember to enable the notification for the TX Characteristic on the phone, so that you can send data back to the phone from the nRF52840.</p><div style="clear:both;"></div>