Read this to find out about:
- The ways in which Bluetooth mesh networking is superior to earlier wireless networking technologies used in lighting control systems
- How to embed Bluetooth mesh networking capability in a luminaire using off-the-shelf components or modules
- Hardware and software kits and tools available now to accelerate the design and deployment of Bluetooth mesh lighting control systems
By François Mirand
EMEA Technical Director at Future LightingSolutions, a division of Future Electronics
If the optimistic claims of commentators on the lighting industry are to be believed, the long hoped-for dream has become reality: there is, it is said, a networking technology for implementing sophisticated wireless lighting control which is affordable, interoperable, easy to deploy, scalable, flexible and future-proof. This technology is Bluetooth® mesh networking, a capability provided by a recent version of the Bluetooth specifications.
It is fair to say that various component suppliers and solution providers to the lighting industry have made bold claims in the past for other wireless technologies such as ZigBee® and the EnOcean radio standard.
So how much faith should we have that this new Bluetooth technology is going to be any more widely adopted in lighting control than those earlier wireless platforms, and will last any longer?
A Universal Technology for Connecting Wireless Nodes
In fact, the new Bluetooth mesh technology is fundamentally different from any wireless networking system deployed in lighting control, and these differences have a profound effect on its value to lighting suppliers and users. Bluetooth mesh networking offers these benefits:
- A universal, supplier-independent industry standard. Any manufacturer can develop standards-compliant hardware. Any qualified Bluetooth mesh device will interoperate with any other qualified device in a mesh network.
- Bluetooth wireless capability is built into every one of the billions of mobile phones and laptop computers in use today. So the devices that people carry with them every day are already able to connect to, and operate, any Bluetooth-based wireless lighting controls.
- Inherently reliable and secure: a mesh network provides multiple pathways for the transmission of messages. Unlike in a conventional network topology based on a central controller or gateway, a single failed node cannot disable the entire network. Strong security features are built into the protocol stack.
- Inherently scalable: the footprint of a conventional network based around a central controller is limited by the transmission range of the controller. The footprint of a Bluetooth mesh network, in which each node acts as a repeater or bridge to the next nearest node, may be continually extended by adding new nodes in range of any existing node. The maximum span between any two nodes is typically up to 25m inside a building. And building operators are not tied to the use of fixtures and devices from a single supplier and any qualified Bluetooth mesh device from any manufacturer may be added to an existing network.
- Easy to deploy: the nodes in a Bluetooth mesh network may be discovered and configured on-site according to a predesigned scheme by any Bluetooth-enabled smartphone or laptop computer.
- Future-proof: Bluetooth is a rigorously developed open standard which maintains backwards compatibility to protect the longevity of users’ investments in network devices.
Scalable, flexible, reliable, future-proof: these attributes of Bluetooth mesh technology are the characteristics that the lighting industry has been demanding, and which earlier wireless networking technologies were unable to provide as fully as a Bluetooth mesh.
But is it possible to gain the benefits of implementing this technology in production lighting equipment designs today?
The Elements of A Wireless Lighting Control System
A Bluetooth mesh-based wireless lighting control network consists ofhardware, software, control and configuration components, as shown inFigure 1.
Fig. 1: The components of a Bluetooth mesh wireless lighting control system
The hardware is the end nodes, as no central controller or gateway is required in a Bluetooth mesh network: each luminaire, sensor and actuator (such as a dimmer switch) has its own Bluetooth System-on-Chip (SoC), a device which incorporates a 2.4GHz Bluetooth Low Energy radio and a microcontroller which can run the Bluetooth mesh protocol stack as well as the application firmware. In a luminaire, the Bluetooth radio may be embedded in just one of its components. For instance, in a luminaire which integrates a presence detection sensor, an LED driver and an LED light engine, the Bluetooth radio may be in any one of them, and Bluetooth control signals received by this component may be passed on to the other components of the luminaire via their wired connections.
Today, this Bluetooth capability may be provided by a Murata sensor module such as the LBCC2ZZ1 series. This small sensor, which may be screwed into a luminaire’s housing, combines occupancy and daylight sensors with a 0 to 10V or two-wire DALI control output and a Bluetooth radio. The device runs a Silvair qualified Bluetooth mesh protocol stack and is therefore fully interoperable with any other qualified Bluetooth mesh node.
Bluetooth capability in a luminaire may alternatively be provided by the CNB30/40/50 series LED drivers under development at ERP Power, which will also provide a modular Bluetooth mesh capability. Or the luminaire manufacturer can add Bluetooth capability to an LED controller featuring a u-blox (formerly Rigado) BMD-300 or BMD-301 module. Because the u-blox product is a complete radio module, its integration into a light controller does not require any RF expertise on the part of the system developer, nor complex RF design and certification.
For fixture controllers and occupancy, daylight and motion sensor nodes, qualified Bluetooth mesh products are also available from suppliers such as Magnum Innovations or McWong, and soon from top tier lighting components suppliers.
So qualified Bluetooth mesh nodes provide wireless communications capability. The format and management of the messages that they carry is determined by protocol firmware.
The specifications of all official Bluetooth networking technologies, including Bluetooth mesh, are determined by the Bluetooth Special Interest Group (SIG) (www.bluetooth.com). The SIG is made up of representatives of member companies from across many industries. A standard-setting process which calls for collaboration between multiple independent entities inevitably takes time. While the Bluetooth mesh specifications were under development, various companies released proprietary Bluetooth mesh firmware: of these, Casambi is the best-known brand.
While suppliers of proprietary Bluetooth mesh protocols have the flexibility to enhance the features of their product as quickly as needed, without taking the time to gain approval from third parties, their products have one serious drawback: limited interoperability. A Casambi mesh network only works with devices which run the proprietary Casambi mesh firmware, which is a much smaller pool of products than the wider market of qualified Bluetooth mesh products.
Fortunately, the wait for the industry-standard Bluetooth mesh specification is over. What is more, certified Bluetooth mesh firmware is available from suppliers including Polish-Californian company Silvair, a participant in the Bluetooth SIG’s mesh networking standard-setting committee.
The Bluetooth mesh firmware supplied by Silvair is configured for use in wireless lighting control networks. This means that, as well as supporting the core mesh networking function, it also provides lighting-control ‘models’, in Bluetooth-speak. Bluetooth models are sets of messages which can be used in particular kinds of applications. Examples include Light On/Off messages, Occupancy State messages and Transition Time messages.
Silvair also provides a complete suite of tools for setting up a lighting installation. These include:
- A production software programming tool for loading the firmware on an OEM’s Bluetooth radio SoC
- A suite of commissioning tools and an app, to configure a network off-site, and then on-site to discover and commission connected devices using a smartphone or laptop computer
- Cloud software for remote user monitoring and control of an installation via a browser. (Remote monitoring requires the addition of a Bluetooth internet gateway or access point, which has no impact on the network configuration, but only exists to provide an interface to the outside world.)
So the protocol firmware enables the end nodes (luminaires, sensors and actuators) to communicate with each other, to interface with the other elements of the lighting system such as LED drivers, and to form a mesh network.
How is the Network Actually Formed in Practice?
This aspect of system implementation has in the past given installers the most headaches. When commissioning a DALI network, for instance, the wired network elements require a logical address scheme. A single error in either the wiring or the programming of the addresses will cause the control system to fail. The same applies to almost all wired and wireless network technologies that use any form of addressing.
Bluetooth mesh technology eliminates this problem. This is because it is an information-centric network. Nodes do not address each other: rather, the network follows a publisher-subscriber model (see Figure 2). A node can publish information: for example, a user control panel might publish a button press event in a specific zone. In real life, this might occur when a user wants to increase the brightness of the lighting in a conference room. Nodes which subscribe to this category of information will then act on the message content. For instance, an ERP Power Bluetooth LED driver in a luminaire in this conference room will increase the current to the LED light engine that it supplies.
Fig. 2: A Bluetooth mesh network operates on a publisher/subscribermodel. (Image credit: www.bluetooth.com)
This publish/subscribe networking principle radically changes the commissioning process. To configure a node, the installer simply needs to specify the types of network messages to which it is subscribed. Should the network around it change, or a faulty node be replaced, or asensor or actuator be added, the existing nodes need no re-configuration. And all qualified Bluetooth mesh components from any vendor can beconfigured and commissioned using the same, vendor-agnostic tool, such as the Silvair Commissioning app.
Commissioning tools also enable online monitoring of a pre-planned lighting scheme, to provide for error-free installation by multiplecontractors on a single site.
Fig. 3: The Bluetooth mesh Demo Kit from Future Lighting Solutions gives OEMs a model for the implementation of wireless control technology. (Image credit: Future Electronics)
The Lighting Control Technology of the Future, Available Today
As described above, various qualified Bluetooth mesh-capable hardware devices are available to buy now via a distributor such as Future Lighting Solutions. Silvair’s Bluetooth mesh production-ready protocol firmware is also available, together with a fullfeatured commissioning tool.
Lighting equipment manufacturers and systems suppliers are able now to implement fully-fledged projects for wireless lighting control over a Bluetooth mesh network. In many cases, system development will be accelerated by the use of a reference design platform such as the Bluetooth mesh Demo Kit from Future Lighting Solutions, as shown in Figure 3, which is backed by technical support from the company’s expert applications engineers.
So while earlier wireless lighting control technologies might have faltered for various reasons, the prospect for industry-wide adoption of Bluetooth mesh networking technology looks promising.