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Noisy Trace Mystery


I have a mystery on my hands. The highlight trace is the step pulse for the stepper motor driver ( DRV8826 ). When I attach the O-Scope probe to the stepper test point ( The via on the trace ) it runs wild!!!! Then when I move my hand it also causes the stepper motor to run eraclicy. Denping where my hand is it runs slowly or very violent steps!! Even with the probe disconnected.

Does anyone have a clue what's causing the weird behavior?

If you're wondering about the large hole, there for fan mounts.

The step pulse is generated by the logic controller (Adafruit Itsy Bitsy 32U4 3V GPIO Pin 5 ).