Duet 2 Wifi: Expansion breakout board heater short
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Hardware setup:
Duet 2 wifi with a Duet Expansion Breakout Board connected. 3 stepper drivers on ports 5,6,7 and heater 6 and 7 populated (see pictures)Issue:
Heater 6 and heater 7 are contaminating each other's signal. When heater 7 (set up as a GPIO pin) is activated, Heater 6's PWM signal also sees a change in voltage (slightly out of phase with H7).We have been running these boards with a modified heater 7 pin. There is a resistor and capacitor in series, jumping the ground and signal pins in order to smooth out noise that we were experiencing. See picture.
After a few months of use, somehow signal from H6 and H7 are getting mixed together. When H6 is active, H7 sees voltage, and vice-versa. We are pretty sure that it is an issue of a contaminated ground signal, but even after the resistor+capacitor is removed, the problem persists.
We would like to prevent these issues from happening in the future.!
