How Do I Wire a Four-Wire (Potentiometer Feedback) Actuator?
Feedback actuators like the PA-14P add a built-in potentiometer, enabling precise position sensing with a microcontroller. This article explains the four-wire connection and how to calibrate the signal.
The Four Wires Explained
| Wire | Colour (typical) | Function | Connect To |
|---|---|---|---|
| Motor + | Red | Motor power positive | H-bridge output A+ |
| Motor – | Black | Motor power negative | H-bridge output A– |
| Pot Vcc | Green | Potentiometer supply (5 V) | Arduino 5 V pin |
| Pot Signal | White | Variable voltage 0–5 V | Arduino analog pin (e.g. A0) |
| Pot GND | Yellow | Potentiometer ground | Arduino GND |
Never connect pot wires to motor power The potentiometer runs on 5 V signal-level current. Connecting it to 12 V motor power will destroy the sensor. Keep motor and feedback wiring circuits completely separate.
Calibrating the Position Signal
The internal potentiometer does not rotate through its full range — the actual ADC readings at full retract and full extend will be some subset of 0–1023. You must calibrate before relying on position data.
1. Drive to full retract
Power the motor to fully retract the actuator. Note the
analogRead(A0) value — save this as POT_MIN.2. Drive to full extend
Power the motor to fully extend the actuator. Note the
analogRead(A0) value — save this as POT_MAX.3. Map to position
Use Arduino's
map() function: int pos_mm = map(analogRead(A0), POT_MIN, POT_MAX, 0, stroke_mm); where stroke_mm is your actuator's stroke length in mm.4. Add noise filter (optional)
Place a 0.1 µF ceramic capacitor between the signal wire and GND at the Arduino pin to suppress electrical noise from the motor.
PA Blog Reference
How an Arduino or Raspberry Pi Communicates with the PA-04-HS — detailed code examples for feedback actuator control including PA's own potentiometer guidance.