Motor speed control with PWM in Arduino - Mini Project: Build & Apply

Motor speed control with PWM

📖 Scenario: You have a small DC motor connected to an Arduino. You want to control its speed smoothly using PWM (Pulse Width Modulation). This is like adjusting the brightness of a lamp by changing how long it stays on and off quickly.

🎯 Goal: Build a simple Arduino program that sets up the motor pin, defines a speed value, uses PWM to control the motor speed, and prints the speed to the Serial Monitor.

📋 What You'll Learn

Use pin 9 for the motor control output

Create a variable called motorPin and set it to 9

Create a variable called speed and set it to 128 (half speed)

Use analogWrite() to send the speed value to the motor pin

Print the speed value to the Serial Monitor using Serial.println()

💡 Why This Matters

🌍 Real World

Controlling motor speed with PWM is common in robotics, fans, and toys where smooth speed control is needed.

💼 Career

Understanding PWM and motor control is important for embedded systems engineers and anyone working with hardware and electronics.

1

Set up the motor pin

Create an integer variable called motorPin and set it to 9. Then, in the setup() function, set motorPin as an output using pinMode(). Also, start the serial communication at 9600 baud with Serial.begin(9600).

Arduino

int motorPin = 9;

void setup() {
  // Set motorPin as output
  // Start serial communication at 9600 baud
  // Your code here
}

void loop() {
  // Your code here
}

Hint

Use pinMode(motorPin, OUTPUT); inside setup() to prepare the pin for output. Use Serial.begin(9600); to start serial communication.

2

Define the motor speed

Create an integer variable called speed and set it to 128 (which is about half speed). Add this variable above the setup() function.

Arduino

int motorPin = 9;
int speed = 128;  // Set motor speed to half

void setup() {
  pinMode(motorPin, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  // Your code here
}

Hint

Declare int speed = 128; before setup() so it can be used anywhere in the program.

3

Control the motor speed with PWM

Inside the loop() function, use analogWrite() to send the speed value to motorPin. This will control the motor speed using PWM.

Arduino

int motorPin = 9;
int speed = 128;

void setup() {
  pinMode(motorPin, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  // Send PWM signal to motorPin with speed value
  // Your code here
}

Hint

Use analogWrite(motorPin, speed); inside loop() to control motor speed.

4

Print the motor speed to Serial Monitor

Still inside the loop() function, add a line to print the speed value to the Serial Monitor using Serial.println(speed);. This helps you see the speed value on your computer.

Arduino

int motorPin = 9;
int speed = 128;

void setup() {
  pinMode(motorPin, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  analogWrite(motorPin, speed);
  // Print speed value to Serial Monitor
  // Your code here
}

Hint

Use Serial.println(speed); to print the speed value so you can see it on your computer screen.