How to DFU Nrf52840DK boards over a "serial" topology network?

[Chris Baudia]

Hi!

We'd like to understand the most reliable way for DFU OTA our Nrf52840DK boards over a "serial" topology network?

We are using nRF5 SDK 15.2.0 and our configuration is as follow:

Gateway <--> Node1 <--> Node2 <--> Node3

Nodes are connected in multi-link point to point as follow:

Gateway (peripheral) <---> [Node 1 (central) -- Node 1 (peripheral)] <---> [Node 2 (central) -- Node 2 (peripheral)]

Ideally, the gateway would download the new firmware and pass it over the nodes that will run a background DFU process. Downloading the new firmware from the gateway is under control but how to "automatically" update all the nodes in the network?

Thanks in advance!

-Chris

[Joakim Jakobsen]

Hi.

Apologize for the long delay in response.

Do you still need assistance on this topic?

Br,
Joakim

[Chris Baudia]

Hi Joakim,

Thanks for replying. Yes, we still need some assistance on this. Can you help?

Thanks!

-Chris

[Chris Baudia]

Thanks Joakim, much appreciated.

We are designing a system that will pull information from our server in order to know whether there is a new firmware version ready to be installed. If this is the case, the gateway will download the new firmware and each node will run a background DFU. By "automatic", I meant without any physical intervention on the network (not even using a mobile app).

Our concern is that we need a reliable DFU procedure with rollback feature in case of something goes wrong. We were thinking starting to DFU the last node then notify the upstream node when done etc etc until we reach the gateway.

I was hoping that we could use an existing procedure or library for that.

[Chris Baudia]

Thanks Joakim,

In our case, we are not using a mesh network or star topology. Each nodes are connected in serial and each node is both a central and peripheral device (see my previous diagram). 

We would have to propagate the new firmware all along the network then decide when to DFU each node.

[Joakim Jakobsen]

Hi.

We don't have a "dfu master" code that could run on the nRF52. And DFU in the nRF5 SDK isn't background DFU.

Maybe you could consider Bluetooth Mesh? The DFU solution there should be suitable for your network. It's background DFU, and the nodes can relay the DFU to the entire network.

Br,
Joakim

[Chris Baudia]

Thanks a lot Joakim!

Unfortunately Bluetooth Mesh is not suitable for our purposes, mainly due to higher battery consumption and lower range.

We are contemplating using this example https://infocenter.nordicsemi.com/index.jsp?topic=%2Fsdk_nrf5_v16.0.0%2Fbackground_dfu_application.html as a first step. They mention nrf5 SDK and background DFU API - would this be suitable for our project?

Regards,

-Chris 

[Joakim Jakobsen]

I would not recommend that. That is part of the IoT libraries, which enable IPv6 over Bluetooth low energy.

nRF5 SDK v17.0.0
------------------------
Release Date: June, 2020
Highlights:
- Added support for a new chip: nRF52820
- Added support for a new SoftDevice: S122
 (size-optimized central-only Bluetooth Low Energy SoftDevice)
- Added a driver for the new RF front-end module nRF21540
- Removed IoT components and examples
- Removed Keil 4 support

From v.17.0.0 the IoT components were deprecated due to very little interest.

Br,
Joakim