DfuModule (Abstract)

The DfuModule allows all nodes participating in a mesh to be updated over the mesh. Using a MeshGateway makes it possible to update the whole infrastructure from the cloud. It is even possible to update a heterogenous mesh with different devices that need different firmware.

Not only does the DfuModule allow to replace BlueRange Mesh, the SoftDevice and the Bootloader, it can also be used to update 3rd party controllers connected via UART, SPI, I2C, etc.

In order to update BlueRange Mesh, the DfuModule works in conjunction with a proprietary bootloader. The mesh stays fully functional while an update is received and all services on the mesh can still run during update distribution. Once all nodes have received the update, it is installed by all nodes in less than a few seconds and the infrastructure reboots.

When updating a 3rd party component, the update is distributed by the standard implementation to all relevant nodes. Afterwards, a custom update protocol needs to be implemented between the BlueRange Mesh controller and the 3rd party controller.

If a node finds out that is has to drop a DFU chunk (e.g. because the flash is currently busy) it is allowed, but not enforced to send out a DFU_CHUNK_DROPPED message. This message is sent to the DFU sender to immediately inform him about the dropped chunk so that the sender is able to immediately put that chunk back into the queue of chunks to send.

When a node receives the DFUAllChunksTransmitted message it replies with a list of up to MAX_REPORTED_MISSING_CHUNKS chunks that are missing on that node. Instead of iterating the list of all chunks from the start, each node iterates it at some random index inside the array of all chunks and checks for missing chunks starting with this random chunk. This procedure speeds up DFU because every node in the mesh is able to report different missing chunks with less clashes between nodes. This way the sender of the DFU (e.g. a Bluerange Gateway) is able to fill its chunk sending queue more efficiently.

An implementation of the mesh update using the M-Way MeshGateway is provided to customer. A version that runs on mobile operating systems is available as well.