Industrial
House and garden go wireless
Richard Ward, semiconductor marketing manager, Rutronik talks about how wireless technologies can be used around the home and garden
T Smart gardening
his summer’s heat wave has been challenging for gardeners. Nevertheless, artificial irrigation should be kept to a minimum as water resources are scarce. If you have a large garden and have bought a smart moisture sensor with a smartphone connection in recent years, you will probably have noticed that the range is severely limited. For a window box, these gadgets work well, but in park-like gardens, you have to build a proprietary sub-GHz sensor network and translate the data into a standard network somewhere near the house using a gateway – be it Wi-Fi or Ethernet. The technical complexity of such a sensor network deters hobby gardeners for fear of installation and failure. However, since the first Bluetooth 5- enabled smartphones came on the market, it became much easier to make such an application. Bluetooth Low Energy previously relied exclusively on a 1Mbps data transfer rate. That's quite a lot compared to 250Kbps on ZigBee or typical 10Kbps on sub-GHz alternatives. The recipe was: "Just wake up and send quickly, then sleep".
Since Bluetooth 5, three more transmission modes have been added. Two of them serve a wider range and are therefore well suited for smart garden projects. Two or eight bits are encoded to transmit a payload, giving a transfer rate of 500Kbps or 125Kbps. As part of a diploma thesis, Rutronik was able to confirm the free-field reach with a range of up to one kilometre. Reliable and practical, the wireless sensors work up to about 500 metres. A preliminary development kit with a nRF52840 pre- series chip from Nordic Semiconductor was used. Refinements on the production-ready SoC and firmware, as well as the use of a better antenna (the kit has only one printed antenna), should extend the range further. Thus, it is now possible to run a moisture sensor with a small button cell for many months (or indefinitely with a solar cell) and send data directly to a Bluetooth 5-enabled smartphone, tablet or laptop. Leaving home is not an issue either. The nRF52840 can be extended with an nRF91 meaning that, in addition to the short-distance radio technologies Bluetooth 5, ZigBee 3.0, Thread, ANT and Gazell, energy-saving mobile cellular technologies NB-IoT and LTE-M and optional GPS are also available. Thus, the sensors in the garden can be reached and read directly from anywhere in the world. The same technologies can also be used to control the irrigation and shading.
Smart home
Even those with no garden can benefit from the innovations in Bluetooth 5. The third new transmission mode allows a doubling of the previous Bluetooth low- energy data transmission rate. In conjunction with the Data Packet Length Extension, this means that simple video streams can now be transmitted. The energy consumption is lower and the required hardware considerably cheaper than previous Wi-Fi implementations. These advances, together with improved battery life, are likely to accelerate the
22 September 2018 Components in Electronics
adoption of smart gadgets, such video doorbells and robot vacuum cleaners with cameras, as purchase price or cabling requirements become less of an issue. NB-IoT and LTE-M are also expected to
affect the smart home. Electricity, gas and water meters are constantly monitored by utility companies, consumers and property managers. If these low power cellular technologies were adopted in the home it would reduce the need for technicians to read meters by radio from the street and avoid the necessity of using private networks, such as Wi-Fi. This would also pave the way for an emerging integrated smart grid that could be used to actively manage smart appliance use, maximising energy efficiency. It remains unclear whether the new mobile technologies, in combination with new framework contracts of the providers, will prevail. Consequently, it would be wise to prepare a Plan B or, better still, a Plan C with multi-protocol solutions.
Plan B and C and D for unexpected developments The electronics world is in a major upheaval. Sigma's Z-Wave protocol appears vulnerable as Sigma was acquired by a company that itself sits on the board of directors of the THREAD alliance and was previously known for Bluetooth ICs. The Z-Wave, EnOcean and BidCos protocols all operate in the sub-GHz frequency range, which means these technologies will probably never find their way into smartphones. They will require a separate protocol/frequency converter –
often referred to as a smart home hub,
gateway or access point. The long-range modes of Bluetooth 5, which can now also be transmitted through multiple walls or long gardens with power-saving 2.4 GHz technologies, are currently proving to be capable of replacing other transmission technologies. The nRF52840 from Nordic
Semiconductor is one solution that could address the uncertainties of future wireless protocol adoption. The chip supports Bluetooth 5, ZigBee 3.0, Thread, ANT, NFC, USB and proprietary wireless protocols such as Gazell, WDP and Shock Burst. The RS9116 from Redpine Signals is also an all-round wireless SoC. It also supports Bluetooth 5, ZigBee 3.0 and Thread. In addition, it supports classic Bluetooth (EDR) and Wi-Fi. Both devices offer the option to perform a subsequent update "over the air" thanks to flash memory technology. Thus, both the radio protocols and the customer-specific application programs can be updated and adapted at any time later in the field. Rutronik’s Wireless Competence
Centre, established in 2005 to handle the requirements of IoT (before the term was even coined), regularly provides advice on topics including certifications, protocols, profiles, alliances, high-frequency behaviour, sizing of antenna, matching networks and security aspects. The team of product specialists and application engineers can draw from a portfolio of 40 radio technology suppliers to develop the best solutions whichever wireless technology is selected.
www.rutronik.com www.cieonline.co.uk
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