espruino_2v09.134_nrf52840.hexis most probably full hex file with softdevice included. to build
--applicationdfu zip you should take the intermediate file called espruino_2v09.134_nrf52840.app_hex which is only the application.
Also the softdevice version must match what adafruit bootloader currently uses. Or if it doesn't use any softdevice (the newest one can be build like that?) you probably need to flash matching softdevice too - make another zip package with
--softdevicesoftdevice.hex , not
--applicationand flash both zips separately. see the end of espruino build output for file names, you should see mergehex running.
or alternatively it may be easier to convert full hex file you have to uf2 instead of dfu zip and flash that over usb as per https://github.com/adafruit/Adafruit_nRF52_Bootloader#making-your-own-uf2
I was hoping to be able to use the nRF52840 port on the Adafruit nRF52840 Feather (that uses the MDBT50Q module). I managed to successfully compile the .hex file using the attached board file that I based on a combination of the NRF52840DK.py and MDBT42Q.py files.
I don't have the tiny SWD cable on hand, so I was hoping to just use Adafruit's bootloader. I generated a DFU package using
and then successfully flashed it using
Unfortunately I can't connect to the board over BLE afterwards, and it also doesn't mount over USB. Any chance that this could work, or should I just bite the bullet and get a J-Link with the right cable?