Nuts and Volts - September 2007

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When I first started this series, I knew I wanted

to build a wireless weather station. In no

way could I have imagined how well the overall system would function, nor could I have envisioned its versatility.

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YOUR WORLD

Build a Wireless Weather System: Part 1

In this article, it all

comes together.

The wired 1Wire network has five main disadvantages:

5) If lightning strikes your weather pole, you run the chance of blowing up your computer or display system.

If you have already built a PC or microcontroller-based weather station connected to a 1Wire network, you may be asking yourself why you should go to all the effort and expense of converting it to wireless.

1) Your system is tethered and you have to run a cable to the location where you want to place the display. This can be problematic and time consuming.

2) You are limited to the length of the cable and the number of items you can reliably place on the cable.

3) If you want to add additional sensors to various locations, this can prove almost impossible if you don’t have access to attic or basement areas.

4) With a wired system, you generally only have a single display system.

■ FIGURE 1

With a wireless system, all these problems will be solved. The only cable that needs to be run is for a power source. This is simply two wires and in many cases can be a very short run. You can even power your weather pole with a set of solar cells and a rechargeable battery.

The heart of our wireless system is a Zigbee mesh network. You have probably read about mesh networks, but this is your chance to actually build one and put it to work. Once the network is built, you will be able to add sensors or displays to any location in your home.

In addition, we are going to add extra features like the ability to create as many display systems as we like without having to change the network in any way. For instance, I can add a PC interface to the system by simply

^■^FIGURE ²adding a Zigbee unit to an RS-232 card and I can start collecting data. At the same time, I can build a small LCD display for my desktop. I can add a large LED sign display to the front entrance of my lab