Potentiometer for DC Motor Speed Control

Arduino DC Motor Speed Control Using Potentiometer

Arduino DC Motor Speed Control Using Potentiometer is a simple motor-control setup using an Arduino, motor driver and potentiometer.

The potentiometer is connected to the Arduino's A0 analog input. The Arduino reads the potentiometer value and maps it to a 0–255 PWM range.

The PWM value is applied to the motor driver's enable pin to control the motor speed.

Potentiometer → Arduino A0 → PWM → Motor Driver → DC Motor

Connections

Device	Pin	Arduino	Function
Potentiometer	VCC	5V	Power
Potentiometer	GND	GND	Ground
Potentiometer	Wiper / Output	A0	Analog input
Motor Driver	A1	D5	Motor direction control
Motor Driver	A2	D6	Motor direction control
Motor Driver	Enable A	D9	Motor PWM speed control

Arduino motor speed control using potentiometer

Potentiometer

The potentiometer provides an analog voltage to the Arduino A0 pin.

The Arduino reads the potentiometer using its analog-to-digital converter (ADC).

The analog reading ranges from:

0 to 1023

The program maps this value to the PWM range:

0 to 255

The mapping used by the program is:

speed = map(potVal, 0, 1023, 0, 255)

Motor Direction

The motor direction is fixed using the following control signals:

A1 = HIGH
A2 = LOW

The motor therefore rotates in one direction.

The potentiometer controls the motor speed and does not change the motor direction.

PWM Speed Control

The Arduino generates a PWM signal on D9.

The PWM value is calculated from the potentiometer reading:

PWM = 0 to 255

The calculated PWM value is applied to the motor driver's Enable A pin.

Working

The Arduino continuously performs the following operations:

1. Reads the potentiometer value from A0.
2. Stores the analog reading in potVal.
3. Maps the value from 0–1023 to 0–255.
4. Sets the motor direction using A1 = HIGH and A2 = LOW.
5. Applies the PWM value to Enable A.
6. Displays the potentiometer value and PWM value on the Serial Monitor.
7. Waits for 200 ms before repeating the process.

The overall operation is:

Potentiometer → Analog Reading → PWM Mapping → Motor Speed

Serial Monitor

The Serial Monitor is set to 9600 baud.

The program displays the potentiometer value and corresponding PWM speed value.

Example:

Potentiometer Value: 0  |  Motor Speed (PWM): 0
Potentiometer Value: 512  |  Motor Speed (PWM): 127
Potentiometer Value: 1023  |  Motor Speed (PWM): 255

Arduino Code

// © 2026, Cognifront. Member of The IoT Kits Family.

// Controlling DC Motor with potentiometer and display output on serial monitor

// Define analog input pin connected to the potentiometer
const int Pot = A0;

// Define motor control pins
const int motorA1 = 5;   // Motor driver input A1 (direction control)
const int motorA2 = 6;   // Motor driver input A2 (direction control)
const int enableA = 9;   // Motor driver enable pin (PWM speed control)

void setup() {
  // Start Serial communication for debugging and monitoring
  Serial.begin(9600);

  // Configure potentiometer pin as input (optional for analogRead)
  pinMode(Pot, INPUT);

  // Configure motor control pins as outputs
  pinMode(motorA1, OUTPUT);
  pinMode(motorA2, OUTPUT);
  pinMode(enableA, OUTPUT);
}

void loop() {
  // Read potentiometer value (range 0–1023 from ADC)
  int potVal = analogRead(Pot);           
  
  // Map potentiometer range to motor speed range (0–255 for PWM)
  int speed = map(potVal, 0, 1023, 0, 255);  

  // Set motor direction: A1 HIGH, A2 LOW → rotate in one direction
  digitalWrite(motorA1, HIGH);
  digitalWrite(motorA2, LOW);

  // Control motor speed using PWM signal on enable pin
  analogWrite(enableA, speed);     

  // Display potentiometer value and motor speed on Serial Monitor
  Serial.print("Potentiometer Value: ");
  Serial.print(potVal);
  Serial.print("  |  Motor Speed (PWM): ");
  Serial.println(speed);

  // Small delay for readability in Serial Monitor
  delay(200);          
}

Observation

The Serial Monitor is set to 9600 baud.

As the potentiometer is rotated, the Potentiometer Value changes according to the position of the potentiometer.

The corresponding Motor Speed (PWM) value changes between 0 and 255.

The motor rotates in the direction specified by:

A1 = HIGH
A2 = LOW

Result

The Arduino successfully reads the potentiometer value, maps it to a PWM value, and controls the speed of the DC motor through the motor driver's enable pin.

The motor direction remains fixed while the potentiometer controls the motor speed.