Selecting a Wireless Sensor Development Platform | RF Designline

Here are a few quotes from this article on wireless design, note the link for zigbee and the tinyos link.

Selecting a Wireless Sensor Development Platform

This article will present the problems a designer will face when implementing a wireless sensor network and the factors that are important in deciding which development platform to select. [...]
One of the more interesting parts of the software layers in a wireless sensor network is the Zigbee software stack. Texas instrument offers a free version of the stack called Z-Stack. Z-Stack is compliant with the Zigbee 2006 specification and several platforms. A link to TI's offering is given here: http://focus.ti.com/docs/toolsw/folders/print/z-stack.html
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In order to build support for TCP/IP, USB mass storage devices or provide parallel execution of software tasks one needs to resort to a RTOS. A good free one for sensor devices is Tiny OS. For more information the reader is encouraged to visit the following web sites: www.tinyos.net, and www.sensinode.com.