Automating my home

What is a computer worth if it is not connected to the real world? When I got my first computer in elementary school (the famous Commodore 64), I took some optocouplers and triacs and created a light show. I even used the Analog Joystick Input to sync the lights to the music.

That was so great! I thought of all the things I could do with my Commodore. Controlling robots, cars ... But the coolest of all, was automating my house (which was, of course, far from reality in that time). Now, more than two decades later, it is finally time to do something about it.

In the past two years, I have evaluated quite a few options, when it comes to the home automation protocols:

• X10
• Zigbee
• ZWave
• "simple" 802.15.4
• KNX/EIB
• Central wiring
• 6LowPan
• WiFi

The first question I had to answer, was whether to buy the whole system off the shelf or to build it on my own. The price tag of the built systems and my interest in electronics helped me to go for the DIY aproach. I didn't want to rush, I took my time studying all available options. I thought about cost, complexity, simplicity, extensibility, adaptability ...

The Protocol

After quite a lot of consideration, I decided to use WiFi for communication. I've looked at Zigbee for a long time, but it is far too complex, even for vendors. 6LowPan has low power consumption and mesh network, but power was not such a big issue for me and I could deal with the range by adding extra WiFi routers.

The Concept

I don't want to put too much logic onto devices. That complicates their code and communication protocols. That is what Zigbee does and that is the main reason I didn't like it. So the system should have a centralized server for complex operations like Scene management and User interface. 

The devices should be simple, but still able to operate independently from the central server. I decided not to split the command (like button) from the actuator (ex. lights, blinds, ...). They are connected to the same board and don't need a server to operate. The devices respond to simple REST commands with a status XML file.

I will post more details of the system as it gets built. I will publish the schematics, PCB and source code (some kind of open source licence). Feel free to comment and to use my work if you find it useful.