https://devzone.nordicsemi.com/f/nordic-q-a/68551/programming-of-bootloader-softwareHi, I am developing a PCB with the nRF52840 device fitted. I need to program the bootloader into it. Is there any way that this can be achieved via the USB pins? Or does it HAVE to be through SWDIO/CLK pins? I have been supplied a nRF52840DK whichen-USTelligent Community 13Fri, 20 Nov 2020 12:59:05 GMThttps://devzone.nordicsemi.com/thread/281105?ContentTypeID=1Fri, 20 Nov 2020 12:59:05 GMT137ad170-7792-4731-bb38-c0d22fbe4515:342ae656-5de7-4c81-8143-e87ac82fb834ovrebekk<p>Hi Steve</p> <p>Unfortunately this is not possible. In order to program the device through USB you need a USB bootloader in the flash, and out of the factory the flash is empty.&nbsp;</p> <p>Without a bootloader in place the only option is to program it through the SWD interface.&nbsp;</p> <p>The companion chip on the DK has a SWD connection with the nRF52 device, allowing it to program and debug the nRF chip directly.&nbsp;</p> <p>Best regards<br />Torbjørn</p><div style="clear:both;"></div>