Replacing an IR remote with arduino

Hello all,

I'm thinking of a project where I basically make a thermostat that turns the air conditioner on/off by sending it the same IR signal that its remote does. I was about to ask how I would go about figuring out what "message" the remote sends so I can replicate it with an arduino, but then I realized it's probably just as simple as reading it with an IR sensor and printing out the value? Or is it more complicated? I have never worked with IR before so I don't know if it has any intricacies that I'm overlooking?

Actually considering the limitations of IR (requires line of sight, which a wireless thermostat won't be guaranteed to have), I'm considering perhaps using RF (or maybe even Bluetooth? WiFi?) instead, and putting an extra thingy next to the air conditioner that receives the RF signal and send the IR signal.

Anyone done a project similar to this before? Any other creative suggestions would be welcome!

See the IRremote library examples, how to dump the codes sent by your remote control. An IR sensor is required for that part of the project, of course.

For sending the same codes you need an IR LED, and a current limiting resistor, and the IRremote library, of course.

IR light is reflected by most surfaces, line of sight is not required. You can place the Arduino and IR diode in the same room, add a RF receiver module to receive the commands, and send the according codes by IR to your air conditioner.

Be warned that many air conditioners use a IR code that is MUCH longer than usual. You may find that the IRremote library needs to have a buffer size increased to be able to receive the full code.

DrDiettrich:
See the IRremote library examples, how to dump the codes sent by your remote control. An IR sensor is required for that part of the project, of course.

For sending the same codes you need an IR LED, and a current limiting resistor, and the IRremote library, of course.

IR light is reflected by most surfaces, line of sight is not required. You can place the Arduino and IR diode in the same room, add a RF receiver module to receive the commands, and send the according codes by IR to your air conditioner.

Well, while IR does reflect from surfaces, it usually takes a few tries at different angles to get the remote to work from the room nextdoor, so it's not very reliable in this case, since I won't know whether it received the message or not, and sending it multiple times would toggle the ACU on and off.

I think either way I might need to incorporate a way to make the arduino detect whether the ACU is running or not, with the "interface" device that I put next to it. (I could possibly hack into its power light, or maybe use a sound sensor?)

johnwasser:
Be warned that many air conditioners use a IR code that is MUCH longer than usual. You may find that the IRremote library needs to have a buffer size increased to be able to receive the full code.

Hmm interesting, it's a really old model, so I guess I'll have to see how long the codes are.

Several ways exist for measuring the ACU on/off state. Then you can transmit that information back to the operator.