February
2005, Issue 175
Zeroing
in on ZigBee (Part 1)
Introduction
to the Standard
Will
the ZigBee standard successfully emerge from the world
of technical committees and marketing hype? If so,
will it be accessible enough for you to use in simple
low-cost projects? In this two-part series of articles,
Pete investigates these questions and more.
by
Pete Cross
In
order to be useful, a radio communication standard must
be obtainable, affordable, and understandable. It must
be able to be interfaced with no more than a few microcontroller
I/O lines and be supported by inexpensive development
tools. 802.11x is too expensive and complicated. UWB
isn’t there yet. Single-frequency solutions are affordable,
but they’re hardly reliable in the face of rapid changes
in attenuation, multipath fading, and in-channel interference.
Proprietary frequency-agile solutions are available,
but this “valued added” approach has been developed
by companies hoping to recoup their investments by making
you pay for far more than the hardware. Because no one
vendor offers a device in every application domain,
proprietary solutions have incompatibility built right
in.
What
you need is an open standard in which the chip makers
generate revenue by selling a sophisticated yet easy-to-use
chip. The companies will charge for the foundry costs
and not the IP in some clever but closed protocol whose
details remain hidden and inflexible. Furthermore, the
companies won’t charge for the IP because the smarts
are already open in the form of the IEEE 802.15.4 standard
(the communication layers operating in the lower layers
of ZigBee). The IP is equally available to any IC developer
wishing to make a competing product. This leaves the
chip makers’ to strive to deliver the best standard
implementation in silicon at the best price.
