Low cost button/switch to connect to OpenHAB


what would be the most low cost solution to have a button/switch to control events in OpenHAB ?

Let’s say for example when I am planning to use a KNX binary input I would also need a KNX interface at the OpenHAB server. That would mean $$$.

I was looking into RS485 as there is a board for the Raspberry Pi available for $16 only. But what to use on the button side and what protocol to use in the software ?

I would prefer if communication would be possible via some kind of BUS, so that multiple switches could communicate over just a few wires. In case there are cheaper solutions for 2 wires for each switch, that would be fine to.

Does anyone has some good ideas or directions to look into ?

Thanks for any help!


If you have the Pi and it’s in wiring range, connect to its GPIO pins, use openHAB GPIO binding to control them.
To switch loads larger than the 5VDC that the Pi delivers, attach a relay board (2€ on *bay).