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12 eTech - ISSUE 6 eTech - ISSUE 6 13

Think globally, act locally

While electromagnetic radiation in the form of radio waves

has been exploited for over a century, without the incredible success of mobile phones its real commercial potential may yet remain unrealised. While cellular technology provided a focus for R&D as well as a return on that investment, it has encouraged and enabled the development of an ever widening array of wireless technologies. Though the basic principles remain unchanged, the various regulations and protocols that are applied to them continue to define the world around us.

Perhaps unsurprisingly, wireless technologies that operate in the unlicensed part of the spectrum have seen the greatest amount of interest and as those frequencies become increasingly congested so too does the need for encoding techniques and protocols that are able to cope with the ‘noise’ from other devices.This, along with the need for reliable interoperability, has led to the evolution of industry standards, governed by independent bodies which attempt to accommodate both the commercial and technical requirements of developers and consumers alike.

One such standard is IEEE 802.15.4, often referred to by its ‘brand name’ of ZigBee. It sits

alongside other standards from the same group (802.15) which defines wireless personal area networks (WPAN), and is itself a subset of the more overarching group, 802, which defines local area networking in general and is not restricted to wireless technologies.

While the standard defines the physical (PHY) and media access (MAC) layers, it is the set of protocols developed to exploit the underlying network architecture that is actually known as ZigBee. Although the ‘brand’ name and the standard are often synonymous, early adopters were prone to using the PHY/MAC technology with proprietary protocols, rather than ZigBee itself, largely due to manufacturers wishing to protect their market share from competitors with compatible solutions.

However, while this may have initially stymied the adoption of ZigBee in some applications areas, it has not impeded the development and adoption of IEEE 802.15.4 compliant solutions. Today there are a number of chipsets and even single-chip solutions available on the market. RS stocks a number of compliant solutions from manufacturers including Texas Instruments, Freescale, Microchip and Atmel.

The right profile The real power of the

802.15.4 standard is its ability to create networks using multiple

nodes within the immediate area, and to use this network to exchange relatively small amounts of data in a power-efficient way. This contrasts with other WPAN technologies, such as WiFi and Bluetooth where, although capable of creating ad hoc networks or peer-to-peer connections, their higher bandwidth and more demanding power requirements will likely preclude them from encroaching on the burgeoning application areas where ZigBee is now being applied.

A significant boost to ZigBee’s appeal – and prerequisite for interoperability and certification – is the development and application of profiles. These effectively define the application area for a ZigBee device and today there exist a number of profiles which cover health care, home automation, smart metering and most recently remote control.

The profile for remote control, which was created after the ZigBee Alliance agreed to cooperate with the RF4CE Consortium, is now beginning to see widespread deployment in consumer electronics. It effectively replaces

the older IR style remote control with an RF device, which doesn’t rely on a clear line-of-sight to operate. More significantly, the integration of ZigBee into consumer devices will not only allow a single remote to control multiple devices, but also enable those devices to communicate directly, to share information about the use and distribution of multimedia, and even shut down equipment automatically when it isn’t being used.

Atmel recently announced that its ATmega128RFA1 single-chip wireless microcontroller has been certified by the ZigBee Alliance to the ZigBee Remote Control standard, which was developed for the

ZigBee RF4CE specification. It means device manufacturers can now integrate Atmel’s solution secure in the knowledge that it will be compatible and interoperable with other devices that have been certified to the same standard.

Low power, short range wireless communication is expected to support greener living through the secure exchange of data using intelligent sensors to control our immediate environment which, in turn, could help the global environment too.

find the latest Zigbee ranges at rswww.com/electronics

“ low power, short range wireless communication is expected to support greener living...”

Wireless Personal area Networks: Zigbee or IEEE 802.15.4? Certification, Standards and alliances.