BLE DFU fails when transferring softdevice + app

[Youssif]

Hi

We're trying to transfer a zip file OTA that consists of both the softdevice and the app. We are using nrf52840 with SDK 14.2.0 and softdevice v6.0.0-6.alpha, and are following the example found in the Nordic playgroud. So far, we have been successful in transferring an app over without any issue. When we try and transfer a both app and softdevice, the OTA process proceeds normally, the app shows that the image is being transferred and the message "Uploading part 1/2" is displayed. However, as soon as part 1/2 is complete, the message "Disconnecting" appears, followed by "Connecting", but that never succeeds and the firmware upgrade process fails.

We have used the nrfutil utility to generate a zip file containing both the softdevice and the app as follows:-

nrfutil.exe pkg generate --sd-req 0xFFFE --sd-id 0xFFFE --hw-version 52 --application-version 4 --application App.hex --softdevice s140_nrf52840_6.0.0-6.alpha_softdevice.hex --key-file key_file.txt App_plus_sd.zip

Any idea why this is happening and what we need to do to fix this?

[Mttrinh]

Hi,

First off, are you updating from softdevice v6.0.0-6.alpha to softdevice v6.0.0-6.alpha? Or are you updating from another softdevice version?

 

[Youssif]

I'm updating from softdevice v6.0.0-6.alpha to softdevice v6.0.0-6.alpha. 

Would there be a difference if it was a different version of the softdevice?

[Mttrinh]

The difference is if it was a different version, for example softdevice v6.0.0-2.alpha, is that it might be API changes between them that would make the DFU fail. Did you perform DFU using nRF Connect?

[Youssif]

I tried performing the DFU using nRF Connect app for Android. Updating the app by itself passes but adding the softdevice makes it fail.

I thought the DFU is capable of updating softdevices with different version numbers as long as it is a minor version change? I have read this in this tutorial, the claim is found in Appendix 1, item 3: Update softdevice and bootloader.

[Mttrinh]

Youssif said:

I thought the DFU is capable of updating softdevices with different version numbers as long as it is a minor version change?

Yes, but alphas have changes. So basically when working with alpha softdevices nothing is guaranteed until the softdevice is production ready.