DrDiettrich:
You send a square wave, not PWM. Eventually sound() may do the trick, depending on the required frequency. Or you program a timer for the right output frequency.
Well a PWM wave with a 50% duty cycle is an ideal square wave.
Thanks for telling me about sound method ,Ill try that.
I think frequency modulation turns out as a rpm output. I would. nevertheless, have to try that! (I'm going to the dyno tomorrow so any heads up and information is appreciated and as always Thanks a lot for being there!)