DFU update error "FW version check failed" on iOS when package contain SD+BL+App and bootloader version is equal than installed

[cavalihno]

HI everyone!

My case:

nRF52832 + toolbox on iOS and Android

I have device pre-programmed using seeger with settings:

--application-version 2 --bootloader-version 2

Next I want to make DFU update using .zip package containing SD+BL+APP with settings:

--application-version 3 --bootloader-version 2

In "BLE Secure DFU Bootloader" document i have read:

Firmware version: If the image contains a bootloader, the image is accepted if the new firmware version is greater than (>) the existing version of the bootloader. If the image contains an application, the image is accepted if the new firmware version is greater than or equal to (>=) the existing version of the bootloader.

So, in my case if aplication version is > than instlled and bootloader version is == than instlled, the update will be only aplication (second part of instalation). In toolbox on Android everything works fine and aplication is installed, but on toolbox on iOS error ocured "FW version check failed".

If in update .zip package I increment bootolader version to +1 than installed, DFU works fine in Androi and iOS in two parts (1:SD+B; 2:APP)

My question is why the Acceptance rules for versions are other in iOS toolbox and Android toolbox (DFU Library).

[Vidar Berg]

Hi,

This is a limitation in the toolbox app on iOS; it aborts DFU if the first init packet is rejected instead of attempting to proceed with the application update. However, as I understand it, it's not a limitation in the DFU library itself, so you can change this behavior if you plan to integrate the library in a custom app. 

[inghowe83]

Hi, How can we change this behavior? We are facing the same error with custom app when using this library. Any example code to change this behavior?

[Vidar Berg]

Hi,

You can split the zip file into two dfu packages, one for sd+bl and one just for the application. Then add the logic in your app to automatically attempt application update if the first packet is rejected due to version mismatch.  

[inghowe83]

Which means our IOS custom app will need to sent 2 dfu package in the following sequence? 

1. sent bl + sd

2. sent app

[Vidar Berg]

Yes, correct. The update procedure will still be the same as when you have a sd+bl+app combined package. I.e., it's two separate updates with two separate init commands. 

[inghowe83]

One question. Will the following operation work in serial without reset

Step:

1. Enter DFU mode

2. sent bl + sd

3. no device reset

4. sent app

5. device reset

[Vidar Berg]

No, not by default, and it may be difficult to change this behavior. Please create a new ticket where you include more information about your requirement if you really need to avoid the reset at step 3.