Hello, I'm playing with a project of making my own security system powered by arduino. I've got most everything running fine if done with wires, but I don't want to have to run a wire to every window in my house so I'm looking at cheap wireless alternatives. Cheap being the keyword here, I could probably make it work using XBee or WiFly, but both of those are kind of expensive to have at each entry point.
I was looking at these on sparkfun:
The question is, is it possible to use the transmitter on the switch side without a controller? In it's simplest form while wired, all I would do is have a reed switch and detect when it's closed vs open. Going wireless, I have to have a way to send this state through the transmitter, and preferably also a way to send when the state changes back to the original state as well. Also going wireless I need a way of identifying what is sending the signal. I'd want to to have each transmitter be able to transmit a unique ID so the main system will know where the alert is coming from. One last thing that I'd ideally like to be able to do is every so often (maybe like a minute to 5 minutes, but it would have to be a fairly accurate and reproducible amount of time) simply transmit an "alive" signal so that the main system knows the unit still has power and has not been tampered with. There would also be IR motion sensors which would have the same basic setup, they would just have an output pin instead of having to read if voltage is making it through or not.
Also, I'm assuming a single receiver would be able to receive signals from multiple transmitters as long as they are all on the same frequency. But I'm guessing I have to worry about signal overlap if two transmitters transmit at the same time. Not really sure if there is anyway to handle that or not without getting into more expensive programming frequency transmitters?
Keep in mind in your answer, that I'm not extremely fluent in electronics. I'm still learning and this project is one of my learning projects (completely within my grasp already if I stuck to wired). So if you recommend anything if you could please explain the function of what you are recommending that would be awesome!
In other aspects of the project (this is just me kind of rambling but I recommend feedback as well), I'm planning on putting a WiFly chip in the main system to connect it to my network in order to enable sending out emails and such if an event occurs. Eventually I'm hoping to get some IP cameras to add to the system to trigger recording and things of that nature as well. Probably will add some external motion activated lights, but that part is easy enough without a controller. I know on that part I can just use a relay attached to the motion sensor to feed power to the lights. I'd have to figure out some way of making the relay stay active for a set amount of time after the motion sensor stops sending a signal down the output pin though. Do they make timed relays? Or perhaps timing chips or something like that?
Thanks for any assistance!