Unable to connect/flash Adafruit Feather nRF52840

[fklement]

Hello,

a student of mine and myself have been trying unsuccessfully since yesterday to get OpenThread onto the Adafruit Feather with the nRF52840.
We have already tried several different methods.

1. using nrffjprog:
Here we get the following error every time, no matter which options we set:

ERROR: No debuggers were discovered.
NOTE: For additional output, try running again with logging enabled (--log).
NOTE: Any generated log error messages will be displayed.

2. via nRF Desktop Connect:
Here we wanted to use the programmer. However, we get the following error when connecting to the microcontroller:

We are using the latest available versions everywhere. We have also checked whether the latest bootloader is installed on the Adafruit Feather.

[Vidar Berg]

Hello,

nrfjprog requires a J-link debugger to program the device. The other alternative if you don't have a debugger, is to try program the FW through the bootloader that adafrauit has put on the chip. I see their UF2 bootloader mentioned here: https://learn.adafruit.com/introducing-the-adafruit-nrf52840-feather?view=all#update-bootloader-use-uf2 supports drag&drop programming.

Best regards,

Vidar

[fklement]

Hello Vidar,

Yes, we have already discovered that nrfjprog requires a J-Link debugger.
We have also tried the possibility with the UF2 bootloader, but unfortunately without success at the moment.

Nevertheless, thank you for your quick answer.

LG,
Felix

[Vidar Berg]

Hello Felix,

Could it be that the openthread FW is not linked to the correct start address? I'm not sure if the UF2 bootloader allow you to ovewrite the Softdevice (Memory Map). If it doesn't, then you have to make sure the OT FW start at address 0x26000 in FLASH, and at 0x20000008 in RAM.

[fklement]

We have now managed to flash the files normally with the nrfjporg and a j-link debugger.
But after flashing the .hex file, the device can no longer be found in the /dev/tty.* devices.

Do you happen to have an idea/guess what we are doing wrong here?

[fklement]

I compiled OT with USB CDC ACM support.
```
UF2 Bootloader 0.7.0 lib/nrfx (v2.0.0) lib/tinyusb (0.12.0-145-g9775e7691) lib/uf2 (remotes/origin/configupdate-9-gadbb8c7)
Model: Adafruit Feather nRF52840 Express
Board-ID: nRF52840-Feather-revD
Date: Jul 13 2022
SoftDevice: S140 6.1.1
```