[Bill Porter] is helping a friend out by designing a simple security system for her home. It relies on Xbee modules to alert a base station when doors are opened, or a pressure mat is stepped on.
The door sensors are quite simple, and you’re probably already familiar with them. One part mounts to the door and has a magnet in it, the mating part mounts to the jamb and has a reed switch that closes a contact when the magnet is in place. The floor mat uses two sheets of conductive material separated by bits of foam. When it is stepped on a circuit is completed and can be sensed by the Xbee as a button press.
These sensors report back to an Arduino base station that has a buzzer and three 8×8 LED modules to scroll a message saying which sensor was tripped. [Bill] does a good job of showing what goes into configuring an Xbee network if you’ve never worked with the hardware before.
You’ll find his demo video after the break.
[youtube=http://www.youtube.com/watch?v=D-Cw5Dm40gE&w=470]
Whenever I see these xbee networks, I can’t help wondering if there’s a cheaper possibility for digital wireless communication, because at $25 a pop, the cost of a larger project can get out of hand quickly.
I have no experiences with them, but cheap bluetooth modules would work, range won’t be great though.
I’ve also seen some china radio’s from Sparkfun and Ebay.
If you want to combine it with an Arduino you could look up Jeenodes, they’re Arduino clones that come with a radio module on the board.
They are also slightly cheaper than a normal Arduino, so in total they’re a lot cheaper than a Arduino + Xbee.
That’s perfect, thanks for the link!
The xbee-price is insane. I use 433MHz china radio’s; a receiver + transmitter for E2,75. Not top quality, but ok for hacking.
Well sure there is. Sparkfun carries some simpler systems for $5-10 each. The XBee module is a pretty “smart” device that can handle a lot of functionality as well as having fairly robust error detection capabilities.
It’s all a matter of what works for you, and (at least in my case) what technology you want to get your arms around for further projects.
You can buy a real house alarm and install it for far far less than a xbee sensor at each entry point. Get a real wireless one for that.
Xbee is not the way to go.
If you sign up with a “big name” alarm and monitoring company they will charge around $100 per extra sensor.
Someone needs to get creative with that annunciator tone … ;-)
The problem with bluetooth is, that i don’t know any device, where a “mesh” mode is possible. Without that you have only 1:1 connections –> bad idea
They way he is using the X-Bees is cool. The X-Bee is actually a really smart device all on it’s own and and for a lot of tasks do not need an MCU. I guess one could hack a cheap radio along with say a DTMF chip to do much the same thing but this does offer some expansion options. Maybe something like a temperature sensor. Or a low battery warning.
Actually we are considering using an analog pin on the Xbee to monitor battery voltage. When a station’s battery goes low, it will say it on the screen.
Actually this got me thinking about a weather station. You could use the XBee to measure wind speed, Direction, temperature, pressure and humidity all without any MCU. Not to mention keep an eye on the battery as well. I would be tempted to put a solar pannel on it just because.
Back to the Bluetooth thing, a little Question:
Does anyone know a module with integrated PAN Profile controlled over for example SPI or something like that? If there would be something like that, that would be a very nice toy.