Designing for ZigBee - Understand the standards before developing wireless products
In a rapidly advancing world that appears to rely more and more on technology, it is evident that wireless technology is becoming one of the most essential of them all. Wireless devices are now found everywhere, from mobile phones to the headsets used to connect them. They are also found in automotive remote keyfobs, antitheft devices, home alarm systems, and the growing number of wireless modems in homes that provide access to the ubiquitous internet. These are only a few of the products which many have come to take for granted in the 21st century.
With wireless capabilities being incorporated into an increasing number of different types of products, there has been a concurrent growth in the different types of wireless technologies available, each of which may be better suited for different applications.
ZigBee is one of those wireless technologies that have emerged to cater to specific needs. It is a low cost, low power, mesh networking technology that offers dramatically increased battery life and has been developed to support applications in a number of industries including:
- Home Automation (HA).
- ZigBee Smart Energy (SE).
- Telecommunication Applications (TA).
- Personal, Home, and Hospital Care (PHHC).
- Commercial Building Automation (CBA).
Essentially, ZigBee is radio device operating in the Industrial, Scientific and Medical (ISM) unlicensed bands (868 MHz, 915 MHz and 2.4 GHz) and is comprised of a radio section based upon the IEEE 802.15.4 specification, with the ZigBee part sitting on top. The mesh network functionality is a type of networking where each node in the network may act as an independent router and allows many different devices to communicate with each other by passing messages through adjacent devices, unlike traditional wireless networks that tend to operate on a one-toone tree structure.
To complement ZigBee, the RF4CE (Radio Frequency for Consumer Electronics)
ZigBee is the device of choice among many product designers because other wireless technologies such as Bluetooth and WiFi are power hungry. This means that they don’t run for very long on batteries, making them ill suited for many applications, such as sensors in places where it isn’t easy to route mains power.
Z-Wave is an example of a technology that competes with ZigBee. But one of the restricting issues with Z-Wave (as with other technologies) is that it is really only supported by one silicon (chipset) manufacturer. This means that OEMs are restricted in their options. ZigBee has six of the top 10 silicon manufacturers in the world supporting ZigBee devices. This is a key benefit, and also offers some technical advantages (eg. higher levels of security, etc).
Devices that fall into the mentioned applications still possess their primary function, but are given an expanded versatility with the integration of ZigBee wireless connectivity. Each application has its own profile which, oversimplified, is a set of instructions that allows each of the ZigBee devices to communicate effectively.
So how do all of these devices work? How do they work together and what typical user scenarios might we encounter? The list is potentially endless. However, one can consider the example of a ZigBee enabled household where applications could include the following:
- A person on their way home could use a cell phone to call home and set the lighting levels and heating temperature to a desired level before arriving home.
- The home may have a water leak detection system that alerts the homeowner via text message if a leak is detected.
- Smart meters providing real time information on the amount of electricity, gas, or water being consumed.
- A homeowner using the same remote control to control their media system (TV, audio, DVD, etc), their lighting, and security system.
- Intelligent domestic products such as ZigBee-enabled clothes washers or dishwashers could be set to operate at times (throughout the night) when energy is at its cheapest.
- An assisted living system monitoring an elderly user and contacting the emergency services should the need arise.
These are all clearly innovative and intelligent applications, with other possibilities being endless, but in order for the consumer to easily identify and understand which of these products is ZigBee enabled and which will work with their existing systems, the product must be endorsed with the ZigBee logo.
The manufacturer can maximize the marketing exposure of its product by ensuring that the end product carries the ZigBee logo, which demonstrates that it is controlled by ZigBee technology. However, before the manufacturer may release its product to the market carrying the ZigBee logo, the product has to undergo a level of certification and regulation testing to demonstrate that it is fit for the purpose.
Certification and regulation are two different procedures. Certification is a process defined by the ZigBee Alliance, wherein the ZigBee device is tested to ensure that it is operating according to the defined protocol for that application. For example, the home automation device will be tested to the HA specification, the smart meter to the smart energy (SE) specification. Regulation is satisfying the legal requirements of the territory in which the product is to be marketed, and depending upon the type of product, the regulatory requirements may vary considerably.
It is very important that when designers undertake the design of a new product, they must consider the standards to which the end product must comply. It is not uncommon for a product to be designed with excellent functionality, but does not satisfy the legal regulatory requirements, such as safety, radio, or EMC. This necessary knowledge is accumulated over many years, but a designer can establish a relationship with a test house or consultancy that can provide the necessary support, such as pre-testing throughout the design cycle. Getting this mix right is very important as time from concept to market varies considerably depending on the product.
This is particularly important with ZigBee products due to the complex nature of...(Read whole article)
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