What kind of circuit would I have to devise in order to read a certain amount of voltage (let's say 0.5V) from my RITTO Twinbus Door Bell system with my RPi?
In detail what I want to achieve: there is a Diode flashing when somebody rings the bell and there is also a 4-legged button soldered on the board I can press to open the door. I want to control these with my RPi. I am capable of soldering and understanding physics but I have gotten a bit rusty on the details.
The alternative would be a 500 Eur+ propietery system, which I want avoid to invest in.