BLE DFU Fota in nrf52840

[Gera64]

Hello

I followed the example from Add DFU support to your application - Software - nRF Connect SDK guides - Nordic DevZone (nordicsemi.com) for current SDK 2.2.0 and it works (had only to adjust path to smp_bt.h in main.c).

Now I'm trying to go further, to make the example more realistic, signing with generated priv.pem the bootloader & the application (Firmware updates — nRF Connect SDK 2.2.99 documentation (nordicsemi.com) is not clear enough for that).

Any ideas / link to tutorials / examples for above feature? Did not find working examples...

Many thanks in advance & Best Regards

Gera64

[Gera64]

Addendum: I'm using "Build" - Button from inside of Visual Studio Code, no external calls to west & co.

Configuration just over prj.conf and CMakeLists.txt of LBS project.

[Raoul]

Hi Gerardo,

In case you didn't know, NCS is set up to automatically generate signed images when you enable MCUboot: https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/mcuboot/readme-ncs.html

In this list of generated files, "app_signed.hex" and "app_update.bin" are the signed images meant for DFU. They can be found in your build folder.

So even though the SMP Server sample readme says so, there is no need to sign manually (Sorry for the confusion there, this sample and its readme are pulled in from the Zephyr repository).

If you do want to sign things manually, you can use the following command (replace the path to your NCS location):

west sign -t imgtool -- --key C:\ncs\v2.1.0\bootloader\mcuboot\root-rsa-2048.pem --header-size 32 --pad-header

"--header-size 32 --pad-header" explicitly aligns and sets the size of the header that imgtool prepends to the hex file. This seems to be necessary.

If you want further examples of bootloader use in NCS, you might be interested in my colleague's Github repo, with "minimal" samples and detailed readmes: samples_for_nrf_connect_sdk/bootloader_samples/

I hope this clarifies things.

Best regards,

Raoul

[Gera64]

Hi Raoul,
many thanks for your response, I'll check out the link you gave me.

As far as I know, the "app_singned.hex & app_update.bin both use the "default" signing with default zephyr/nordic debug key.
How should I configure the VS-Code environment (prj.conf & co) in order to use my own production key?

Best Regards

Gerardo

[Raoul]

Hi Gerardo,

Please check out this page from the my colleague's GitHub repo: https://github.com/hellesvik-nordic/samples_for_nrf_connect_sdk/blob/2c7865423b3af585947f72cd44787ae77c296336/bootloader_samples/keys_and_signatures/README.md

And the following section from the NCS documentation: https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/ug_fw_update.html#using-development-keys

They will have more information on using production keys. Note that this is not related to the VS Code extension, but rather the nRF Connect SDK (meaning these features would work even from the command line, without VS Code).

Best regards,

Raoul

[Gera64]

Now it works.
Solution was to create a file named "mcuboot.conf" inside of the folder "child_image".

In this file add the line CONFIG_BOOT_SIGNATURE_KEY_FILE="<path_to_key_file>/priv.pem". The clue is that the path_to_key_file must be absolute, including drive letter...
Do not use the "standard" proj.conf for that line, as stated in the documentation, since the line will be ignored for signing of mcuboot...

Best Regards

Gerardo