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Also, because of the ZigBee Alliance, a lot of expertise is available in the form of
consulting companies, training companies, or custom engineering services, saving time
for you or your development staff. Developer time can be the single largest expense
in a project, and reducing that time can save significant costs. San Juan Software, the
company I work for, offers ZigBee services. So does LS Research, Develco, Software
Technology Group, and others.
The ZigBee Alliance, which is the alliance of companies who developed and support
ZigBee as a standard, has also defined what are called Application Profiles. These
profiles describe how ZigBee devices interact, specifically between products of certain
types and within certain markets. For example, the Home Automation profile describes
how switches can control lights, how a temperature sensor sends its data to a thermostat
and how that thermostat controls a heating or cooling unit (heater or air conditioner).
A well-defined standard saves effort and money when developing products that need to
interoperate with other vendors.
Development costs are explored in more detail in Chapter 2, “ Deciding on ZigBee. ”
Multiple silicon and stack vendors, ZigBee modules and many available
resources all contribute to low development costs for ZigBee devices.
1.1.3 ZigBee Is Low-Power
What does the ZigBee Alliance mean when it says ZigBee is low-power? The simple
answer is that devices in a ZigBee network can operate for years on a pair of AA
batteries. Depending on the application, these devices can last the entire shelf life of the
batteries, which means if you placed the batteries on a shelf at room temperature with
nothing connected to them, they would run out of juice just as quickly as they would if
they were participating in a ZigBee network, about five years later. No, that doesn’t mean
ZigBee radios do not consume power, it just means that if managed correctly, devices can
last a long time.
Compare this to the time you get on your laptop battery: hours at best. Now, granted, your
laptop is powering a bright screen in addition to WiFi™. Compare this to the life of your cell
phone battery between recharging, especially one with Bluetooth™ enabled: days at best.
The real secret to low power consumption in ZigBee, in addition to radios and
microcontrollers that can sleep, is low duty cycle. A node on a ZigBee network does
not need to keep in constant contact with the network to remain on the network. In fact,
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