Raspberry Flavoured Home Automation - Part 1 - Conception

Introduction
The other day my boss sent me a link to a neat little daughter board now available for your Raspberry Pi. It's called a Razberry and it allows your Pi to connect to to the Z-Wave range of home automation devices.



At first I was intrigued and a little excited by the idea. Home automation and the internet of things has interested me for a long time now but when I went off to look at what I could do with Z-Wave devices I was stopped in my tracks by the prices. Although it looks great on paper the Z-Wave range is more than a little on the expensive side.

Feeling a little deflated I resigned myself to the fact that it's still an expensive luxury that I couldn't afford. But then I thought to myself...

"Well if someone made a Z-Wave to Raspberry Pi board. Then maybe someone else has done something similar with another protocol."

So I did a little searching for Raspberry Pi home automation and found myself looking at www.domoticz.com it was not only compatible with the Pi but actually was downloadable as a Pi image. Promising so far but how will it talk to the home automation hardware?

What happened next sealed the deal for me. I noticed that this software supported (among others) a little device called a RFXCOM 433Mhz USB Transciever. And as luck would have it. I just so happened to have one of these lying around. I'd been given it as a birthday present from my lovely wife some time ago and I used it to experiment with controlling some Bye Bye Standby Plugs from my Arduino.


RFXCOM 433Mhz USB Transciever

The RFXCOM 433Mhz USB Transciever is a small device that you can plug into a USB port. It allows you to send and recieve 433Mhz radio signals to a massive list of supported devices. Although some may feel it is a little pricey (Around £80) lets look at the alternative.

Wireless home automation devices come in many flavours each type of device uses a certain type of communication protocol (think of it as the language the devices use to talk to each other) of which there are almost as many as there are manufacturers. For example the Bye Bye Standby range of products use a protocol called Domia Lite. Another popular protocol is the Lightwave RF protocol. Devices that use Lightwave RF do not understand a device that is using Domia Lite and vice versa. This is mostly the same across the whole home automation market and means generally you need to pick a protocol to use and stick with it. The problem with that is how much you limit your choices. If somewhere down the line you want to add heating control into your setup and find that nobody is making thermostats that use your chosen protocol then you have a big problem. The RFXCOM devices open up these options and allow you to mix and match protocols so long as all the devices in your setup operate on the same frequency (433Mhz in my case).

Nearly all the protocols offer a device that can form a bridge between your RF controlled devices and your home IP network (and by extension the internet). Take Lightwave RF for example. If you are using Lightwave you can buy a device called the Lightwave RF WiFi Link. This box allows you to control your devices from either your home network, the internet or even your phone. Now it's not really fair to compare the RFXCOM directly with something like the WiFi Link as the WiFi Link offers much more than just a communication device. It has a built in web server running it's own software and is generally a lot cleverer than the RFXCOM devices alone. However if you pair the RFXCOM with something like a Raspberry Pi then we have gone a long way towards leveling the playing field.

The WiFi Link costs around £65 and the RFXCOM costs about £80 plus about £25 for the Pi so it's just over £100 vs £65. Is that extra expense worth it? Well I haven't performed a full cost analysis but I think so. You may have spent £35-£40 more but I think you will soon make that money back when you start to shop around for your switches and sensors. For example this Lightwave RF single gang light switch is around £24 which is o.k. if you live in a bedsit but otherwise fitting out a decent sized house is going to get real expensive real quick. With the flexibility offered by our RPi / RFXCOM solution however we can shop around and discover something like this HomeEasy light switch selling for about £10 which to me is a much more reasonable proposition. If you have say 6 switches to automate in your house you have already just saved yourself £90.

Where Was I? Ahh yes...

So I was looking at some full featured software that was open source and more importantly free. I already had the hardware needed to run it (Namely a spare Raspberry Pi and the RFXCOM module). Hmm total bill of materials for giving this a go? £0.00!

I'd be mad not to!

As soon as the kids were in bed I dug out the RFXCOM module and loaded up the windows version of Domoticz. It installed without any bother or complicated configuration and within moments I was looking at the nice simple web interface. I jammed a USB lead into the RFXCOM and told Domoticz which port the device was on. It recognized it immediately now I just needed something to control.

I mentioned above the Bye Bye standby plugs I have used in the past, well I still have one connected in the loft to control the light up there so I grabbed the 4 channel remote for it and started hitting buttons.

Nothing Happened

I hit the buttons again

Still nothing happened. I had thought this was all going far too smoothly. So I clicked around in the web console checking settings to see if I'd missed something. But then I clicked back on the devices tab and there was my 4 channel remote. I had missed something. I'd failed to refresh the page! (Face Palm)

I gave my buttons names on the devices tab and added them to the favorites screen. Next I went to the hallway and gazed up in hope as I clicked the "Loft Lights On" button. When the dark space above my head suddenly illuminated I was more than a little surprised. (I'm a bit of a techno-pessimist).

For the next couple of minutes I stood there with my laptop playing with it.

"Light goes on!... Light goes off!..."
"Light goes on!... Light goes off!..."
"Light goes on!... Light goes... "

"Hang on a minute. This is a web based application. I wonder if it will work on my mobile phone? "

"Let me see 192.168.1...."

"Light goes on!... Light goes off!..."

"THAT IS SO COOL!" (Well for certain values of cool)

That is how this particular home automation project got started. In the next post I will talk about where I see this project heading.