The reason why I was thinking to the 0-10V interface was I found it easy to understand/implement. In fact, although i read something about DSI and DALI, I don't have a clue on how to use them with the RPi. Do you know if it's possible?
Although it seems you already answered HERE
You are correct, I didn't remember that post when I made this one. The DALI protocols
require the units be specifically programmed and I'm not sure how this has to be done.
I'm pretty sure that a Raspberry pi could
be programmed to interface with them but I don't think that anyone has done so yet. (and that scale of programming is well beyond my skills).
unfortunately all DALI ballasts currently on the market only have their addresses settable and viewable with special equipment
DALI is open protocol, so the details are available for anyone to make DALI devices.
DSI similarly has a level of programming required to communicate with the controllers but is a proprietary system of Tridonic, although I know that many lighting control systems manufacturers make Lighting Control Modules that will interface with DSI (so they aren't keeping it exclusively for themselves. They may require a licence fee to allow use of the protocol.
Possibly switchDIMM would be the easiest, just get a mains AC FET and time the on and off signals to control the light level.
this is a fairly good overview of the various lighting control protocols.
Building Management Systems Engineer.