Oh and just in case the question comes up: This is not meant to go commercial and was purely intended to be used for myself to help me cut paper waste and time in the darkroom and still get at least some results per session. With 3 young kids it is generous enough from my significant other to get at least 4 days a month off.. BTW, it also gives me the chance to occupy myself with my new hobby while being away from the darkroom. Most of the stuff was coded on the bus while commuting to work.
Still if someone is interested in that stuff (or even likes to participate), I'd very much like to share what I have so far. Maybe this could also inspire others to come up with a better program (I'm just learning how to code!). In the end you could get at least an f stop timer that way for as low as 35 Euro - that's the price of the relay board.