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!