nRF52840 USB PROGRAMMING

[ecp]

Hello, 

I am planning on using the WLCSP version of the nRF52840 chip on a PCB design. ( nRF52840 - Bluetooth 5.3 SoC - nordicsemi.com )

Is it possible to program the nRF52840 chip through USB instead of through SWD?

From this link: ( Programming )I see that the nRF52840 Dongle has a built-in USB bootloader that allows for USB programming. Is this bootloader available for the nRF52840 chip by itself? If not, is the bootloader available for download in order to flash it to the chip through SWD?

[Peter C]

If the chips are identical, the bootloader should work from the devkit.  As long as the USB is handled with the exact same registers and pin numbers, the bootloader should behave the same way.  you would just need to make sure that the same trigger that they use to put it into DFU mode is also present on your board (reset button or some other switch).  without that trigger in the exact place that the bootloader expects it, it will never enter bootloader mode.