Confused by oscilloscope - square wave signal to RPM

Projects Programming
37

So this is in a vehicle? Automotive electrical systems are extremely noisy.

Can you tell us:

  1. Physically where is pin 8 going?
  2. Where do you connect to ground in the vehicle?
  3. are you connected to ground in two places?
  4. Is your hardware a bare Nano connected to the ECM and the Neopixels?
  5. Do you have any filtering either on the 12V or the ECM in?