Understand nRF52840 Dongle programming with nRFConnect

[Adrian Eggenberger]

Hi

I've played around a couple of hours with the nRF52840 Dongle and tried to understand what can be flashed to the nRF52840 dongle and what can't. This issue is not about the programming of the nRF52840 Dongle with an external j-Link adapter. For my tests I've used the latest nRFConnect  2.6.1 with the 1.0.0 Programmer Application. The system I'm using the tools is a Windows 10.

Here my questions:

- What happens if the hex files I select contains a bootloader? It doesn't show an error on programming, but the original bootloader seems to be still in place on the dongle.
- What combinations of HEX files (application, bootloader, softdevices) can be written to the dongle?
- How can we recover back to an initial image that came preinstalled on delivery?
- Are the bootloader setting known from the bootloader over BLE handled internally by the nRFConnect bootloader?

Another thing that I'm not getting to work is the DFU-Trigger functionality. I was able to program my application to the dongle, but the nRFConnect doesn't see my DFU-Trigger. Is there  a driver needed for the DFU-Trigger? Does it work with different VID/PID combinations than the ones from Nordic?

Regards Adrian

[Marjeris Romero]

Hi Adrian,

It is not possible to overwrite the bootloader during normal operation using the programming app. If you physically connect to the debug interface of the dongle with an external debugger, then there is no memory protection and it is then possible to overwrite the bootloader.

Adrian Eggenberger said:

What combinations of HEX files (application, bootloader, softdevices) can be written to the dongle?

Application + Softdevice.

Adrian Eggenberger said:

How can we recover back to an initial image that came preinstalled on delivery?

Is not exactly the same, but you can upload the "open bootloader" from the SDK from "\examples\dfu\open_bootloader\pca10059_usb".

Best Regards,

Marjeris

[Ed Wios]

@msromero Me, too, have been troubling with the nRF52840 dongle's bootloader for days, trying to get a custom bootloader onto the dongle without success. Now seeing your reply I finally understood.

But then, the issue is when I tried to program a bootloader using the nRF Connect, I've got this error [DFU failed: Error message for known extended error code from DFU target: The init packet does not contain a signature. This bootloader requires DFU updates to be signed.] thus implying the boot loader on the dongle can be programmed via the nRF Connect. That's what got me confused since the nRF Connect does not accept a zip file, and I have found no way to sign a .hex file using my private key generated from nrfutil...

If what you said still hold true, then the nRF Connect need to be updated to reflect the correct error when someone is trying to overwrite the bootloader.

I am using nRF Connect on the Mac OS.

BR/

Ed

[Marjeris Romero]

Hi Ed,

That's right, I should have explained things more in detailed. The error message you get it's just because the bootloader demands to have a signed package in order to start the update process. This is done so you don't overwrite the bootloader by accident.

You can still overwrite the bootloader using the SWI interface.

Regards,

Marjeris

[MATHEUS]

Hello I'm trying to flash a bootloader from adafuit but I'm not able to generate use such keys.

Is there any link of the private key you are referring to so i can sign the zip package?

The bootloader that I'm trying to flash is this one: https://github.com/adafruit/Adafruit_nRF52_Bootloader/releases/download/0.2.11/pca10059_bootloader-0.2.11_s140_6.1.1.hex

[Marjeris Romero]

Hi Matheus, please open a new ticket with a new question.