https://devzone.nordicsemi.com/f/nordic-q-a/95569/is-possible-using-mcumgr-dfu-without-jlinkMy setup is: RaspberryPI (linux)-&gt; USB Host Custom board -&gt; Without JLink OB I have tried this guide over my nrf52840DK and it&#39;s ok, but the DK board has JLink OB and my custom has not. I cant use an external JLink. I suppose it should be possibleen-USTelligent Community 13Wed, 11 Jan 2023 08:58:56 GMThttps://devzone.nordicsemi.com/thread/404240?ContentTypeID=1Wed, 11 Jan 2023 08:58:56 GMT137ad170-7792-4731-bb38-c0d22fbe4515:808e0594-c891-418a-b416-f26e7e8344e2Vidar Berg<p>Hello,</p> <p>Yes, you can use mcumgr&nbsp;to upload FW through the nRF52840&#39;s USB interface. The prerequisite for this is that&nbsp;your board has been programmed with a compatible bootloader&nbsp;and application&nbsp;first.&nbsp; Note that our chips are not pre-programmed, so initial programming must be performed via the debug interface (<a title="Debug and trace" href="https://infocenter.nordicsemi.com/topic/ps_nrf52840/dif.html?cp=4_0_0_3_7">Debug and trace</a>) with a dedicated programmer. You&nbsp;may use the&nbsp;<a title="Debug output" href="https://infocenter.nordicsemi.com/topic/ug_nrf52840_dk/UG/dk/hw_debug_out.html?cp=4_0_4_7_9">Debug output</a>&nbsp;port on your DK for this.</p> <p>Best regards,</p> <p>Vidar</p><div style="clear:both;"></div>