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The base of the central nervous system of buildings

bluetooth next
Figure 1: Bluetooth SIG and DALI have defined a standardized gateway to control D4i luminaires via Bluetooth Mesh.

Author Kerstin Nasser, Corporate Product Manager Wireless de Rutronik

Modern building management systems can make a decisive contribution to improving energy efficiency and comfort, and thus intelligent lighting systems become the basis for a kind of central nervous system. Although Bluetooth often forms the "nerve pathways," other wireless standards offer benefits as well. Smart lighting is one of the most important market sectors for Bluetooth: according to the “2021 Bluetooth Market Update” report by Bluetooth SIG (Special Interest Group), 27 percent of supplied Bluetooth devices are already being used in smart lighting systems. This puts them second behind smart device apps (35 percent), but growing faster.

There are good reasons for this: connected lighting systems with intelligent control can reduce energy costs by 70 to 75 percent. At the same time, they increase comfort levels by allowing, for example, users to change the light color as desired or automatically adapt lighting to natural daylight (human-focused lighting or Human-Centric Lighting – HCL). This concept offers a spectrum of light ranging from deep blue components in the morning, which have an invigorating effect, to more red components in the evening, which have a calming effect.

And, for example, presence detectors can be used. Depending on whether someone is in the room (or not), the light can be turned on or off automatically. An automatic change based on the intensity of lighting or ambient light in a room is also possible.

lighting is everywhere

Lighting is used in virtually every part of a building. This makes it the obvious infrastructure base for new building management approaches, as wireless technology embedded in lighting control devices can also be used for many other applications. The Bluetooth SIG estimates that by 2029, commercial connected lighting will generate $19.100 billion in global revenue.

In collaboration with DALI (Digital Addressable Lighting Interface) Alliance, Bluetooth SIG has defined a Gateway that allows to monitor and control the luminaires with the D4i certified via Bluetooth Mesh. In this way, lighting components from various manufacturers can “understand” each other and interoperate seamlessly.

Beyond lighting, it is possible to implement, for example, functions of asset tracking and location or indoor navigation using smart lighting solutions. Objects to be tracked must be equipped with a beacon. The wireless transceiver in the luminaires receives its data signal as soon as the object comes within range. Subsequently, the position of the object can be derived using the building plan. This is particularly useful in large warehouses or factories, where it significantly reduces search times. Therefore, processes are optimized and costs are reduced. In the hospitals, this tracking capability can help increase speed and quality by quickly locating mobile healthcare teams or hospital beds.

Networked via Bluetooth

Smart lighting systems use Bluetooth Mesh to provide reliable and secure communication. This allows you to benefit from the low power consumption rate and the minimum latency of Bluetooth Low Energy (LE) in those systems where hundreds or thousands of devices of various brands need to communicate with each other. Bluetooth Mesh uses the so-called flooding principle, which guarantees that messages reach their destination. This is possible because all network participants can communicate directly with each other – and if one participant fails, the message is transferred via another path. In addition, mobile phones can be integrated into a BLE network or mesh (meshed) with the corresponding application (Whatsapp), thus making it possible to switch on the luminaires without the need for Gateway no internet connection.

Bluetooth Mesh is supported, for example, by the multiprotocol SoCs of the series nRF52 and nRF53 de Nordic Semiconductor. In combination with the nRF21540, users can enjoy a range extension of sixteen times. The nRF5340 incorporates two Arm Cortex-M33 processors. The application processor is performance-optimized, can be clocked at 64 or 128 MHz, and has 1 MB Flash, 512 KB RAM, floating point unit (FPU), 8 KB bidirectional associative cache, and memory capabilities. DSP instruction. The 64 MHz network processor is optimized for low power and high efficiency (101 CoreMark/mA) and has 256 KB Flash and 64 KB RAM. Apart from Bluetooth LE and Mesh, the nRF5340 also supports NFC, Thread and Zigbee. It offers SPI, QSPI, and Hi-Speed ​​USB and is rated to 105°C (221°F) operating temperature.

Numerous vendors supply modules based on these SoCs from Nordic Semiconductor. Many of them have already integrated antennas and are pre-certified for the main markets (CE, FCC and IC). Thus, they help shorten development time and reduce costs. This applies, for example, to the series ISP de InsightSiP, the modules PAN1780 and PAN1781 de Panasonic, the model MBN52832 de Murata and various modules iVativ and EnOcean.

The Insight SiP ISP family is characterized by its small form factor, which is particularly suitable in lighting applications. The modules are based on various Nordic ICs and can be easily interchanged due to pin compatibility.

The Panasonic PAN1780 module is based on the Nordic nRF52840-IC. Thanks to the integrated Arm Cortex-M4F with 1 MB Flash and 256 kB RAM, it can be used in standalone mode (stand-alone), which helps save cost and space. For its part, PAN1781 is based on the Nordic nRF52820, which has 256 kB of Flash and 32 kB of RAM and supports angle of arrival (AoA) and angle of departure (AoD) of the version 5.1 of the Bluetooth Core Specification, called radiogoniometry (RDF). Therefore, this Bluetooth standard enables even more precise positioning.

The SX-ULPGN-BTZ de Flint is based on the SoC Qualcomm QCA4020. With dual-band 802.11 a/b/g/n Wi-Fi, Bluetooth LE and 802.15.4 (Zigbee and Thread Pro R21) connectivity, it's also ideal for lighting systems and many other applications.

Cypress/Infineon also offers Bluetooth Mesh chips and modules for lighting solutions such as CI CYW20706 or the module CYBT-343026-01, which is based on the CYW20706 IC itself.

multi-sensor
Figure 2. The EnOcean STM 550 multisensor
for home automation systems and
IoT applications are self-powered by accumulating energy.

Other wireless standards

In addition to Bluetooth LE and Bluetooth Mesh, other wireless standards are also common in lighting applications, such as the On Ocean, Thread, Zigbee or Wi-Fi.

Wi-Fi's advantage over Bluetooth lies in its significantly greater range. However, the resulting requirement for more power is also perhaps the biggest disadvantage of this technology. In addition, the integration of luminaires in a Wi-Fi network is somewhat more complex, since you have to enter a password and the service set identifier (SSID – Service Set Identifier) for each luminaire. And a Wi-Fi network can reach its limit when many luminaires are connected.

Zigbee can be used to create a mesh network (mesh) large and robust. If a network participant fails, the information can be resent via an alternate path and is therefore not lost. When configuring the network, a bridge or hub is also required, which in turn is connected to the WLAN router. The bridge or hub sends the command (on/off) to the luminaires via Zigbee. Unlike in Bluetooth Mesh, data transmission is routed as individual devices (coordinator, router, and end devices) are assigned different tasks. This means that a certain route is specified for the data through the network.

Thread works in a similar way to Zigbee: here too the data distribution is routed, for example, via a predefined path. Thread is a protocol mesh based on IPv6. This makes it relatively easy to integrate into large IP networks. This protocol is also supported by Nordic CIs and forms the perfect foundation for Thread-based application layers such as Matter, HomeKit, DALI+, KNX IoT, OCF, etc.

The EnOcean sub-GHz wireless standard (868 MHz according to the RED specification, 902 MHz according to the FCC/IC specification, and 928 MHz according to the ARIB specification) offers high reliability when sending short telegrams. There is little probability of collision within a network, thus enabling a large sensor network. Also, there is no interference with DECT or WLAN. The use of rolling code and 128 AES encryption ensures advanced data security. Inside buildings, the EnOcean wireless standard achieves coverage of up to 30 meters.

The EnOcean company is particularly known for its energy storage technology. It offers maintenance-free wireless sensors based on the EnOcean wireless standard, as well as Bluetooth and Zigbee. The new IoT multisensor STM 550 (Fig 2) provides status information (open/closed) thanks to a magnetic contact and can measure temperature, humidity, acceleration/orientation and lighting. The integrated solar cell produces enough energy for the measurements and the transmission of the result data using, for example, Bluetooth, Zigbee or the EnOcean standard.

Conclusion

Whether Bluetooth, Bluetooth Mesh, EnOcean, WLAN, Thread or Zigbee – all wireless standards have their specific advantages and disadvantages and it is necessary to decide individually which one is most appropriate for each application. However, they share something in common: they form the central nervous system for smart home lighting, and therefore bring improvements in efficiency, convenience, comfort, and extensions to, for example, include a navigation and tracking system.