Programming of bootloader software

[Steve Smith]

Hi,

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 which can be accessed and programmed through USB connector with nRFConnect. However, on closer inspection this appears to be via a second microcontroller. If I try to connect to the nRF52840 IC directly (via the USB conn on the side of the dev kit) then the nRFConnect software does not recognise the device.

Any help or pointers on this would be greatly appreciated, as this device is completely new to me.

Regards

Steve

[ovrebekk]

Hi Steve

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. 

Without a bootloader in place the only option is to program it through the SWD interface. 

The companion chip on the DK has a SWD connection with the nRF52 device, allowing it to program and debug the nRF chip directly. 

Best regards
Torbjørn