CSR set to release Mesh-radio-for-Bluetooth development kit
CSRMesh uses the company’s µEnergy product family, and is a protocol running over Bluetooth Smart. It permits up to 65000 nodes in a single network, and multiple co-existing networks, and CSR intends that it be used in applications such as home automation; it has already been applied to lighting, and will be extended to other functions in the near future.
Asked what Bluetooth can bring to mesh networked systems, CSR’s Rick Walker – senior product marketing manager – says that above all else; it’s the smartphone. Virtually every recent smartphone, he notes, comes ready-equipped with Bluetooth Smart. Any phone can therefore host an app to directly interface with a network of devices, either controlling or collecting data. You do not need any form of gateway or additional hardware between the phone and the network.
CSRMesh is – in contrast to other network technologies that form specific routes through the network – a flood mesh protocol. That is, any device receiving a message either identifies that the message is for itself, or it re-broadcasts the message. CSRmesh does not use full IP addressing but adopts a light weight data structure which enables much lower power and lower processing burden for simple devices.
How does Bluetooth, in the shape of battery-powered nodes, implement a flood-mesh and still contain power such that long battery life is possible? It is, Walker says, all about minimising the time that each node spends “listening” – that is, with its receiver powered up and waiting for a message. In a typical home-automation context originating or repeating a message will be relatively infrequent event and therefore, less significant for battery drain; and CSR says that its µEnergy range already achieves this with low current drain while active. The Mesh protocol needs to maximise the probability of intercepting a transmitted message while minimising wake-to-sleep Rx ratios.
CSR’s Walker says that its developers have demonstrated that messages can be sent from one end of a multinode network, and acknowledgement returned, with reliability and with low latency. There are features of the network you can exploit, he notes; some nodes will (by reason of their function) have access to mains power, and can therefore afford to be “awake” for longer; and also, you can set up parameters such as number of repetitions, or message validity duration. That is, loosely speaking, a node may say, “I have seen and repeated this message x times, and will ignore it if it appears again,” or, “this message is y msec old and therefore out of date, so it should not be re-broadcast.
The CSRmesh Development Kit will include a set of tools for evaluation and software development – software will be downloadable – and will comprise development boards, the CSR xIDE software development environment, USB programmer and interface cables, example CSRmesh applications for the development board, and – to Rick Walker’s main point about the power of the Smartphone – example host applications and source code for Android (at launch) and Apple iOS (in development).
Development boards will host a CSR1010 IC with 64k EEPROM; PCB antenna, RGB LED, two user pushbuttons and one user slide switch, a power switch and an SPI programming connector. Pads are provided to connect external devices.
At the time of writing, CSR’s website is promising availability of the Kit for “the end of July.”
CSR; www.csr.com/products/csrmesh-development-kit
Steve Hegenderfer, Director of Developer Programs at the Bluetooth SIG, adds, “Bluetooth Smart… offers incredibly low power, simple and secure wireless connectivity and … [is] already an existing standard in the smartphones, tablets and PCs of billions of consumers.
“Device interoperability just isn’t an issue. It has an effective range of up to 100 metres and Bluetooth 4.1, introduced in December last year, added a means to create a dedicated channel which laid the foundations for IPv6 connectivity. Bluetooth Smart mesh is already possible and we’re working to make it a reality under the Bluetooth standard. If you want to speak to a few things, you can use a niche technology, if you want to speak to a few billion things in an ultra-power efficient way, then Bluetooth Smart is the way.
“Smart Home has been stuck as the next big thing for 60 years. In order to take it mainstream, you need a mainstream wireless technology.”
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