Maybe I am way over my head here, but here it is:
I am trying to regulate a spindle RPM. The tachymeter part is now working flawlessly.
Now I am on the PID part, to control and regulate that speed. I am using the PID library on my Arduino Due. It "looks" like it works, but it does not.....
What I mean is that, if I measure with a multimeter the output directly from the Due, I can see the voltage increase steadily from a few millivolts up to 2.75/2.8 Volts, as it should.
BUT, if I measure after going through the logic level converter (as the spindle speed controler is for 5 volts), the voltage min is +- 1.3 volts (instead of a few millivolts), and max is 1.565 volts.
It's clearly not working as I thought it would. What am I missing here?