As I just created a test-setup using the Ramps board and the IR sensor the area of the schematics on my first post is the only thing connected to my arduino. TMC2130 is on X position of my test (Ramps 1.3) setup.
On my example sketch (in the video and code above) I used digitalRead.
The sensor is choosen properly and approved by my customer (which machined all the aluminium and acrylic parts and 3d printed the holder for the sensor).
The video shows that detection in general works well (everytime the hole is in the right position the display turns on and off properly) - as long as I'm not using a serial connection. When using the serial monitor everything starts going crazy - that's why I just build the test-setup using the old ramps board...
Before I designed the hardware, I tested the sensor on my laboratory PSU. It works fine - as long as I'm not using the serial monitor....which makes developing really, really difficult (I wanted the ramps test setup to be able to analyze in realtime using the serial monitor - but the behavior it the same as on the final PCB...).
@anon35827816: thanks for your reply. So I'm going to build an impedance converter today.
Luckily the cable used hast 2 free veins!
Before I changet the value to 10 Megs, I tested using 33K which didn't work at all...
So using 10Megs shows alternating values as the impedance of the AtMega2560 ADC has a too low impedance?
As soon as I add the OP amp, how would you guys start coding the detection?
I've been looking for tutorials...but still don't know where to start from.