nRF5340 + nRF7002 multi-image HTTPS FOTA

RE: nRF5340 + nRF7002 multi-image HTTPS FOTA

Håkon Alseth — Mon, 16 Jun 2025 17:27:51 GMT

Hi,

[quote user="blisowski"]Since the FOTA Download library hasn't been tested with multi-image updates, is there anything that might be problematic in this regard?[/quote]

This is hard to pin-point, as the library is not fully tested in this way, but there should not be much issues as long as you filter out correctly based on the image number. In general, I would recommend testing generic DFU/OTA functions extensively to verify that all image types boot successfully.

One library that one of the devs made me aware of is this:

You could have a look at the dfu multi-image library, enabled via CONFIG_DFU_MULTI_IMAGE, which should address the scenario that you're looking at:

https://docs.nordicsemi.com/bundle/ncs-latest/page/nrf/libraries/dfu/dfu_multi_image.html

Zigbee used this in v2.9.x: https://github.com/nrfconnect/sdk-nrf/blob/v2.9-branch/subsys/zigbee/lib/zigbee_fota/src/dfu_multi_target.c

And Matter uses this library as well for OTA image handling.

Kind regards,

Håkon

RE: nRF5340 + nRF7002 multi-image HTTPS FOTA

blisowski — Fri, 13 Jun 2025 15:24:41 GMT

Correct, and I modified the fota_download function to accept an image number as an argument.

Since the FOTA Download library hasn't been tested with multi-image updates, is there anything that might be problematic in this regard? If I download all 3 images before restarting, I can see MCUboot swapping all three images before starting the main application. Am I safe to assume that this is working as a simultaneous multi-image update?

RE: nRF5340 + nRF7002 multi-image HTTPS FOTA

Håkon Alseth — Fri, 13 Jun 2025 14:12:00 GMT

Hi,

I suspect it is these two calls that are hard-coded to '0' on the img_num that is problematic?

https://github.com/nrfconnect/sdk-nrf/blob/v3.0.2/subsys/net/lib/fota_download/src/fota_download.c#L183

https://github.com/nrfconnect/sdk-nrf/blob/v3.0.2/subsys/net/lib/fota_download/src/fota_download.c#L219

The historical reason is that this library was originally made for the nRF91-series devices, and unfortunately; we have not expanded on the library in terms of the image number, to match chips such as the nRF5340. I will report this internally as a feature request.

Kind regards,

Håkon