"Home Automation" with Arduino and 433 MHz - Basics

Besides the 2.4 GHz wireless modules I presented in some older posts, I am working with modules in 433MHz band. In the upcoming posts, I'm going to share my experience with you.


Basics

There were electrically powered shutters installed in my apartment one year ago. These shutters are remote controlled. This calls for "home automation". You could close the shutters automatically when the sun is shining and when you're on holliday the shuttery can be closed and opened randomly to pretend you're at home.

A quick look at the backside of the remote control showed the following:

It couldn't have been better, the control works on the 433MHz band, a so called ISM band. A lot of remote controlled alarms, power outlet and so on work on this band. That's why there are lot of cheap 433MHz transmitters and receivers. Just look for "433 mhz transmitter receiver" on ebay.

The following combination of transmitter and receiver can be bought for about 1 €.

On the left, there is the receiver, on the right, you can see the transmitter. Both modules have three connections (the second and the third pins of the receiver are connected): VCC, GND and data. When you send a HIGH signal to the data pin of the transmitter, it will send a HIGH signal. With the receiver it's vice versa: when it receives a HIGH signal, the data pin is HIGH. So it's pretty easy to transmit a sequence of bits.


The plan

The motor of the shutter has a "standard" EU plug and is pluged into  power outlet. Unfortunately the shutters consume a lot of energy even when they are in standby mode. It would be very unhandy so unplug the shutters everytime you don't need them. It would be much better to use a remote controlled power outlet. As already mentioned, most of these power outlets work on the 433MHz band. So you can kill two birds with one stone: I want to create a system that can control shutters AND power outlet. In practice, it should work like this: if you want to close the shutters, you press a button. At first, the system turns on the power outlet. Then it sends the "close-signal" to the shutters. When the shutters are closed, the power outlet is switched off.