I've been researching home security systems. Honeywell, GE, DSC, Napco - all seem expensive and behind the times.
I want private monitoring of my doors and windows, partitioned to floors of my home and the garage. I figure I could even do without the wall-mounted control panel because I will always have my phone with me to arm or disarm and check status.
I can get a raspberry pi for $25 (at worst) to run the system and standard sensors which aren't so expensive.
The main problem for me then is interfacing with the sensors (wired). I'm new to hardware so I think I should stick to an off-the-shelf USB device rather than try to build it, if possible. I found at least one promising device but it's $100 for few ports and I don't even know that it will meet all the requirements alone.
I thought maybe a salvaged usb/midi keyboard would be a fairly generic solution in which I could brute-replace the keys with sensors. But at $45+ for 25 key device, that's still kinda pricey and complicated. Benefits are that all "keys" can be pressed at once, unlike on a qwerty keyboard and that switching from 25 "zones" to 61 "zones" and up is as simple as upgrading the salvaged keyboard to a longer model.
- The door/window sensors are magnetic and I don't know if the new wire distances and power requirements can be driven by a keyboard's hardware without amps for each one.
- I only need binary input on each channel. Circuit closed or open?
- For power considerations, I don't need to power all devices constantly, but rather scan them individually several times a second.
- Ok, motion detectors and glass break sensors might be nice, if they work the same as the magnet sensors. They need to be powered all the time. Nice-to-have.
- Since this is a security application, anything that can be done to avoid or mitigate sabotage by overloading the hub device from a sensor site seems smart.
Recommendations on how to get this done in a cheap device that is fluent with a standard computer interface? Or is it very very easy to create a custom USB device that can perform this task?