The cap off an addidas deoderant can makes a nice enough base for the orb from a B&Q disco lamp (no link as can’t find it online).  I soldered the ends of some CAT5 to the BlinkM, and left the other ends loose to be shoved into the arduino.

As I’ve got an arduino and ethernet shield, I went for the second largest ABS box and even then, I had to break off the screw connectors on one side so that the plugs could stick through the outside.  I soldered the AM receiver and transmitter onto a small piece of stripboard (also from bitsbox), added a couple of wires for aerials (with a knot in each to prevent someone pulling it out the circuit).  So that’s pretty much the finished product, what a shame!  I will add a thermometer to it so it can become a thermostat in another room – eventually this’ll go in the sitting room, so will have the current cost meter producing one temperature reading from the kitchen, this one in the sitting room, and have just ordered another arduino for my bedroom’s ambient light/thermometer/development board.

The java code has been working nicely, turning the heating on and off via the hacked home-easy plug!  I sent a text from my phone to turn the heating on, very proud of actually finding a use for it as I was stuck in traffic but had friends coming round so the heating would have cut out at 5.30 (it heats up til 5.30, then waits for movement) – only to find there was a street power cut that has lasted 3 days (intermittently)!  So, if the power holds up a little longer, I should get a tweet tomorrow telling me how long the central heating was on for, fingers crossed!

So, time to write the web interface, pretty dull

However, with that over… I’m on a quest to automate my home with arduinos, and central heating is something that “needs” automating. Yes, I could buy a Home Easy central heating controller for £75, but I already have three plugs and in all honesty, nothing to do with them (yet). After reading an article at instructables, I decided to do something similar but hopefully a lot easier. The final result I aimed for was to have my usual central heating/hot water programmer running as usual, but have the home easy plug sitting between it and the pump/boiler so I could make it act like a thermostat. Then, by leaving the central heating on 24×7 on the programmer, I can take full control over it via arduinos and an AM transmitter. Naturally you could use any home easy remote to control the heating as well, but that’s not very exciting! As I’m prone to playing, I also want to be able to bypass the home easy device and let the programmer work as usual – just in case the code/hardware fails!

So, step one was get the stuff out of the home easy plug (HE302S, for those that care). I could have done what instructables said and ruin a screwdriver to unscrew the tamper-proof screws, or I could use brute force – the latter one. Just pry it open from the end opposite the screws and yank. Then stick a screwdriver by the two clips at the end opposite the plug and lever the circuit board out – much easier!

After probing the wires above (while the programmer was on – had to extend the wires out the bottom), I saw that the right-most pin only went live when the central heating was turned on. Hot water (second from right) went on when hot water or central heating were on. So, all I’d need to do is interrupt the right-most pin, letting it go live when I want C/H, and dead when I don’t.

Left to right, Neutral, Live, Hot Water Off (is live most of the time), Blank, Hot Water on (live when either hot water or c/h is on) and Central Heating on.

The wires in the pic above with red are the new wires that I added, a permanent neutral, a timer controlled live feed (right-most pin) and the output wire from my device.

The home easy device needs a neutral, which I took from the C/H programmer’s neutral, a live, which came from the C/H programmer’s right-most pin – that way the home easy device only gets power when the programmer is telling the heating to go on, which will be 24×7 once I’m happy. And then the output of the home easy device should go back to the wire that was in the right-most pin on the C/H programmer. But, I want an override switch, so put a two-way light switch in the middle of this. Pictures speak a thousand words, so you should be able to see what’s going on in the picture.

I didn’t have to isolate the relay as mentioned in the instructables article – this solution seemed much easier…

Net result was in less than 30mins, I can use a remote or my arduino software to turn on/off the heating – and if all goes wrong, I can take the home easy device out of the loop

I struggled last night for several hours trying to get reliable two way communications.  The idea is that every time the arduino receives a home easy command from a remote or motion detector, it sends a message to the MPC-L.  Then, with some funky programming, the server will decide what events to fire off.

Unfortunately while I can reliably receive messages, and reliably send messages, I can’t do both – it just hangs.  I’m thinking it’s the nuelectronics ethernet shield, the software certainly isn’t very nice, so as I’ve only been playing with this for a few days, I’m splashing out on an official shield.  As a by-product of this, it is supported by Nicholas O’Leary’s MQTT code.  So, moving away from last night’s PHP start, I’ll write a small java program to receive these, process them, and fire off any events if need be.

The logic for the event firing will end up being more complicated, but initially, I want a bunch of events/desired actions, and each event has a sequence of signals required, each of which have to happen within a changable amount of time.  Only if a path through the sequence is achieved in the right time will the action be fired.

For example, a motion detector in the hall, and a door open/shut detector on my front door.  An event (i.e. turn off all lights) with a sequence of 1. Motion detector fired, 2. Door opened will detect when someone has just left the house, but obviously you only want it to happen if the time between 1 and 2 isn’t too much, otherwise the person could have walked upstairs and someone else came in through the front door!

I got this working in PHP, so will Java-it-up tonight.  Then will code the more complicated (and more useful) central heating logic (i.e. I want the house at 18 degrees at 7PM, it’s now 16 degrees, and takes 45mins to warm up to 18degrees, so turn on centreal heating at 6.15PM).