Since CSR launched CSRmesh™ a year ago, I have met with people from the world over who are all interested in learning more about it. As more and more developers look to bring easy to use and attractive IoT and smart home products to market, it means more and more questions about the solution head my way. I thought it would be useful to list the queries I hear most often about CSRmesh and answer them here in this post. If the responses here don’t answer some of the questions you have about CSRmesh, don’t hesitate to post in the comments, refer to the wiki or post in the CSR Support forum – one of the team will get back to you. We’ll also post a version of these FAQs on the CSRmesh development kit product page and keep it regularly updated.
- Has mesh been standardized by the Bluetooth SIG?
Not yet, but the Bluetooth SIG is working towards standardization. On February 24th 2015, the SIG issued a press release announcing the formation of the Bluetooth® Smart Mesh Working Group, which is dedicated towards building the architecture that will make mesh networking a standard capability on Bluetooth Smart technology. CSR’s own Head of Global Standards, Robin Heydon, is chairing the Working Group and leading the charge. CSR cannot comment on when standardized mesh will land, but according to the SIG release, the Working Group expects to have the specification ready for prototype testing later in 2015, and the SIG will look to officially adopt profiles in 2016.
- What Bluetooth solutions does CSRmesh run on?
CSRmesh is a protocol that was built with the aim to run on Bluetooth 4.0 and later. Bluetooth Smart is the only prerequisite necessary for CSRmesh to work, and you can run it on our existing generation of Bluetooth 4.0 devices. See our CSR101X product family here – http://www.csr.com/products/csr101x-product-family.
- I would have thought Bluetooth Smart isn’t the most appropriate technology for meshing – aren’t there issues with range and power consumption?
CSRmesh by its very nature addresses these two issues. Bluetooth Smart was designed to be the lowest power radio on the market, and mesh networks were conceived to resolve the issue of range. Some have raised the point that there is a need to be wary of the power consumption of routing nodes, which will be listening and receiving most of the time. However, there is no routing in this mesh and therefore no setup time, no concept of router, coordinator or end device, no extra memory or processing overhead. All nodes are a simple low cost Bluetooth Smart SoC.
CSR recently announced CSRmesh Home Automation which will be available in Q2 2015. This will include sensor and actuator models that specifically address power consumption, response time and latency. Sensors will only wake up when they have data to send. The actuators wake up more frequently to be responsive but they can still sleep a long time. CSRmesh is a flood mesh, and in such a mesh there are more nodes around that are capable of repeating messages, therefore there is a higher chance that messages will get through to receiving nodes. The more nodes you have, the more you can turn the scan rate down.
CSRmesh is much more than just range extension. The intelligence in the network is distributed across all its members. Your lightbulb can proxy for heating sensor values so they can remain asleep most of the time. Your nodes can help you find your misplaced car keys by BLE RSSI. Your porch light comes on when you approach your front door at night by proximity – no other sensors are required. As an example Wireless Cables have developed the AirCable solution using CSRmesh. Their CEO, Juergen Kienhoefer, claims that with a very low ad rate and only about 10ms listen time, the battery impact is pretty low. His measurements are 35uAs for an ad package and about 150uAs for the mesh listener. Based on these measurements, an ad rate of 10 seconds would mean your standard battery could run for months or years.
- How secure is CSRmesh?
I’ve covered the security aspects of CSRmesh in a separate blog post which you can read here.
- Is it easy to integrate CSRmesh with wall control panels and remote controllers?
Yes – CSR partners like Avi-on are doing just that with their home automation solutions for solutions like wireless light switches.
TV remote controls are turning towards using Bluetooth Smart. Although cheaper, IR remotes are no longer useful for Smart TVs. Bluetooth Smart is a great replacement technology because it doesn’t need line of sight, it handles accelerometer and gyros for mouse pointer and motion for gaming and can even support just waving the remote to issue a direct command or even a CSRmesh command. All of this runs on same low cost SOC which also includes CSRmesh.
- How does CSRmesh cope with multiple smartphones/remote controls operating simultaneously? Shouldn’t it be the gateway’s responsibility to handle these complex aspects?
There is no problem with supporting multiple controllers in CSRmesh. The TV remote, light switches and multiple smartphones all have unique addresses on the mesh. CSR even has ways to share the controlling device database to other controllers in a multi controller mesh without a gateway, although this can probably be best done in the cloud. Routing and IPv6 stack running on Bluetooth Smart is an unnecessary and heavy burden, which is why this isn’t enabled in CSRmesh. The whole idea being that the mesh works locally without the need for a gateway or internet connection (which has security benefits too), with no single point of failure if the Internet goes down. When you do need to control, configure and monitor remotely, then for the IP terminates at the gateway and CSRmesh takes over with its own lightweight addressing scheme more suited to Bluetooth Smart devices. Being a broadcast mesh (with flood control and acknowledgements) there is no routing to be done either, no setup time latency and no tables to maintain.
- Is it possible to implement voice communications over mesh?
Bluetooth Smart can support voice commands. The SoCs that make up the CSR101X product family use hardware to process the lower levels of the Bluetooth radio stack. This means that the radio can switch on and off quicker than if it was done via software. There is also more link budget available (on average – 64kb/s) for accurate voice interpretation. Bluetooth Smart is not designed to support voice communications and audio streaming – the bandwidth is just not high enough. However it is high enough to support short voice commands. See our CSR µEnergy® Remote Control Development kit for more information.
- Is CSRmesh hampered by a lot of interference on the 2.4Ghz frequency?
CSRmesh is designed to coexist with Wi-Fi. It only takes a millisecond to send information on the mesh and this is sent on three separate channels (Channels 37, 38 and 39) which are out of range of the most common Wi-Fi router channels. We use all three channels so if one is blocked, there is a good chance the other two will get through. This step is repeated three times, so in effect each message is relayed nine times. This means there is very little chance that a concurrent Wi-Fi network will interfere with the workings of CSRmesh. This is unlike Zigbee and RF4CE networks which have a track record of being trodden on by Wi-Fi interference. The coexistence of Bluetooth and Wi-Fi has been proven by the long history of Bluetooth/Wi-Fi combo chips in smartphones.
- How simple is it to set up a CSRmesh network?
It is incredibly simple. The key point here is that CSRmesh does not need a hub or access point to keep running. All you need to start is one CSRmesh Bluetooth Smart light bulb or switch or smart plug and a smartphone. Download the associated app and away you go – you can start talking to the devices immediately. Then simply add as many more as you wish and you can use the app to group them together as you wish – you will automatically be creating a mesh network for them to relay messages through. Talk to them individually, as a group or all together. There are no expensive hubs to buy or configure and no complex setup. The only time you need a hub is if you want to monitor or control your home when you are away from it, so with CSRmesh Home Automation in Q2 2015 we will be providing low cost Bluetooth Smart to Wi-Fi, IP bridge and gateway solutions for that purpose.
- Is the power consumption low enough for batteries to be practical?
If a device is acting as an active mesh member, then it needs to spend some of its time listening for messages to relay. A device such as a light switch can be a passive mesh member, i.e. it only ever sends a command (when someone presses it) into the mesh and never listens for messages. In this case it is an originator device, not a recipient or a relay device and can live happily off a coin cell battery for several years, but it cannot relay messages for other nodes. For power connected lights, battery life would pose no problem.
In the Home Automation release of CSRmesh developers will have the added capability to tune the scan rate of the node so that it is partially sleepy and can therefore benefit from extended battery life. This feature takes advantage of the flood mesh nature of CSRmesh. By how much you can reduce the scan rate wholly depends upon a couple of things: (i) how many nodes you have around you to relay the message and (ii) how hard (long) the originator tries to send the message. We will issue some guidelines and applications support around this at the time of release.
- What is the maximum network size CSRmesh can support?
The maximum theoretical size that CSRmesh can support is determined by the 16-bit device ID and 16-bit group ID. Therefore up to 64,000 devices can be supported and 64,000 groups per network key.