How to connect "io-homecontrol" skylights to a Raspberry Pi?

Question

Scenario

I want to control my remote controllable skylights with my Raspberry Pi. The windows were installed a few years back and come already with the remote capable io-homecontrol technology, which comes with remotes that can each control one window. Going forward into 2017 I want to interface those devices with a more central system. My goal is to control it via Raspberry Pi.

Unfortunately io-homecontrol is a multi-vendor system that's poorly documented for outsiders. I've found an old blog that details how to make it work by physically connecting the GPIO of the Raspberry Pi to the dissected remote of the skylight. I would very much prefer to forgo so many relays and cracked open remotes.

Question

How do I control io-homecontrol devices via Raspberry Pi without physically attaching the PCB of the remote to it?

Answer 1

You must have an RF interface to communicate with your skylights and unless you are an official partner I doubt that you can obtain all necessary information to build one specially for the Pi.

Also it does not seem to be an ordinary wireless communication technology.

Two-way radio communication complying with the EN 300-220 standard

The io-homecontrol® protocol handles two-way radio communication at frequencies from 868 MHz to 870 MHz. It complies with the EN 300-220 standard for low-power radio applications.

So you either hook up the remote control to the Raspberry. (IMO those relays are quite overkill, some simple transistor can be used to do the switching instead, so the additional hardware would not be so large.)

Or you can buy a TaHoma® box for centralised control and management of the house from a smartphone, tablet or computer connected to the internet. As I understand, it is basically a gateway for io-homecontrol. You only have to connect the Raspberry Pi to the internet to be able to control your lights indirectly.

It is more expensive but you do not have to hack a remote control.

Answer 2

You can buy an 868 MHz radio telemetry transceiver module for some $$, although you would be making an assumption about the on-air protocol being the 'simple' FM (frequency shift keying). To confirm this, you might first want to use an RTL-SDR style USB radio receiver to capture the transmit data. So far so good.

A more significant problem may be the '128-bit' encryption. Assuming that a simple record-replay attack doesn't work, more effort might be required to generate a suitably coded message to get a response. By analysing the transmit data you should be able to at least determine if this is a problem.

Answer 3

Take a look into the Velux KLF200 gateway which can be handled by your PI i.e. with openHAB as interfacing software.