mesh DFU: Is it possible to perform a bootloader and application update within the same mesh DFU transaction?

[Thomas-Brilliant]

I've been doing some development on the nRF Mesh platform for the nRF52832 chipset and I'm relying on the Mesh DFU protocol to update my deployed units. Recently I've been thinking about making some changes to the interface between the mesh bootloader and the application. When I update my units that are already deployed, I would like to update both the bootloader and the application together because this removes any danger of different versions of bootloaders and applications interacting together in incompatible ways.

In the Mesh DFU protocol documentation (infocenter.nordicsemi.com/.../md_doc_libraries_dfu_dfu_protocol.html) I noticed that it says each portion needs to be updated separately:

As part of each transfer mode, the Mesh DFU protocol is using three different transfer types (packages):

• SoftDevice
• bootloader
• application

Each of these three firmware pieces must be transferred separately, and each has its own identifier. Each has also its own area in the memory map.

 

Is there a way for me to update multiple pieces together (e.g. application and bootloader get updated together)? If so, how do I go about achieving it?

[Joakim Jakobsen]

Hi. 

From what I understand there is currently no way to transfer these at the same time. 

I can forward this question to our Mesh developers and ask if they have any suggestions on how this could be implemented, if possible. 

Best regards, 
Joakim Jakobsen

[Joakim Jakobsen]

Hi again. 

Is there a way for me to update multiple pieces together

 I'm afraid this won't be possible. This is due to a limitation both in the Mesh DFU protocol and in the Bootloader. 

Best regards, 
Joakim Jakobsen

[Thomas-Brilliant]

Hey Joakim,

Thanks for the update! In that case, when softdevice updates are issued to deployed devices, how do you maintain compatibility between the new softdevice and the old application?

Thanks,
- Thomas

[Joakim Jakobsen]

Hi.

If you are updating the SD to a versjon that doesn't support the existing application you need to expect some downtime. If the application doesn't support the SD, the application will be invalidated when the BL/SD is transferred and flashed.

However, this usually only applies to major ID versjon changes of the SD. If you are updating the SD from one minor ID to another minor ID, the application should support the new SD.
If you only update the Application, you also need to expect a little bit of downtime when the application is transferred and gets flashed on the device. This would not be in the same range as the downtime updating the BL/SD.

Let me know if you need any more specific information.

Regards,
Joakim Jakobsen.