There are many of these types of projects I've found on the net, but I haven't yet found one that will do exactly what I want. You see, many of the projects out there use simple SSR (solid state relays) to turn on/off a central boiler. This obviously isn't going to work for me since we have a wall-mounted aircon.
So I want a device that has a built-in thermometer and an IR transmitter so I can adjust incrementally the temperature.
I got some inspiration from the following sources:
Controlling a heat pump with Raspberry Pi and USB IR Toy
This guy is using a Raspberry Pi and a IR transmitter to control a heat pump. He uses a Google Calendar for the scheduling and operation. However, it doesn't have a thermometer (and I am not interested in using Google Calendar, but email). But, the essential component, the IR Toy (module with infrared receiver AND transmitter) built in, controlled over USB. And he got it working on a Raspberry Pi.
Raspberry Pi Thermostat
This guy uses a DS18B20-compliant single wire thermometer sensor to communicate temperature readings to the Raspberry Pi. But, he uses SSRs to control the actual airconditioning units.
I did some shopping last night. I found this great website, Seeed Studio which is actually a Shenzhen-based "open hardware facilitation company", and they have all kinds of great toys that they build in house, including the IR module. So, I bought the following:
USB Infrared Toy v2
The product is described as "Assembled USB infrared remote control receiver/transmitter v2 designed by DangerousPrototypes.com. Use a remote control with your computer, view infrared signals on a logic analyzer, capture and replay remote control buttons, and play TV POWER codes."(The emphasis is mine - the ability to capture IR signals will be essential so I will be able to theoretically operate any IR unit.)
One Wire Temperature Sensor
Here's a good resource from the University of Cambridge on how to interface with a thermometer with a Raspberry Pi: http://www.cl.cam.ac.uk/freshers/raspberrypi/tutorials/temperature/. And later on, in case I want to integrate an analog light sensor (for controlling temperature differently during the day from the night): http://www.raspberrypi-spy.co.uk/2012/08/reading-analogue-sensors-with-one-gpio-pin/ - but this is a phase 2 I guess.
So now, the wait game begins. I'll need to wait for it to be shipped. And no doubt it will arrive at my office early in the week so I'll probably need to wait a few days before I can really get started. I suppose I can get a head start on the code...
Photo Credits: http://www.seeedstudio.com