I'm working on a system based on a NodeMCU/ESP8266 WiFi controller, which controls two separate motor units, each consisting of a 12V motor and solenoid actuator. For practical reasons, I need to physically separate the controller box from the motor/actuator boxes by around 6 feet.
Here's a diagram with a single motor unit, capacitors and diodes omitted for clarity. In reality, there will be 2 motor units in parallel with independent control signals:
What's the standard way to wire this to reduce signal degradation due to EMI?
- Combine all conductors (control/GND/12V/3V3) in the same cable. Requires twice as much cable and thicker gauge for all conductors because of high current requirements on 12V/GND, significantly increasing cable cost.
- Separate GND/12V/3V3 conductors from control signals. Control is routed without ground, i.e. no shielding, therefore susceptible to EMI. We cannot also include ground with control, since that would form ground loops.
- Include ground with the control signals, wire 12V/3V3 separately without ground. It feels wrong to wire the positive rails without ground, but not sure why.
Please let me know if there are any other issues with the circuit, e.g. sharing ground between MCU and inductive loads.
Thanks for your help!