6.5.1 Introduction

A DC motor is an actuator that converts electrical energy into rotational mechanical energy.

It is commonly used where continuous rotation is required.

6.5.2 Types

Examples include:

• Brushed DC motor
• Gear motor
• High-speed DC motor
• Coreless DC motor

6.5.3 Working Principle

When current flows through the motor windings, a magnetic field is produced. Interaction between magnetic fields produces rotational motion.

The direction of rotation can be changed by changing the polarity of the motor supply.

6.5.4 DC Motor Driver

An Arduino pin should not normally be used to power a DC motor directly.

A motor driver or suitable transistor/MOSFET circuit should be used.

Common motor drivers include:

• L298N
• L293D
• TB6612FNG

A motor driver allows the Arduino to control:

• Motor direction
• Motor speed
• Motor start/stop

6.5.5 Connecting a DC Motor to Arduino

Example using a motor driver:

Driver	Arduino
IN1	D7
IN2	D8
ENA/PWM	D9
GND	GND
Motor output	DC Motor
Motor supply	External supply

6.5.6 Speed Control Using PWM

PWM can be used to control motor speed.

Arduino Uno PWM values normally range from:

0 to 255

• 0 = motor stopped
• 255 = maximum commanded PWM duty cycle

6.5.7 Direction Control

Example:

IN1 = HIGH

IN2 = LOW

→ Forward

 

IN1 = LOW

IN2 = HIGH

→ Reverse

IN1 = LOW

IN2 = LOW

→ Stop

The exact behavior depends on the motor driver.

6.5.8 Arduino Programming and Code

int IN1 = 7;

int IN2 = 8;

int ENA = 9;

void setup() {

  pinMode(IN1, OUTPUT);

  pinMode(IN2, OUTPUT);

  pinMode(ENA, OUTPUT);

}

void loop() {

  // Forward

  digitalWrite(IN1, HIGH);

  digitalWrite(IN2, LOW);

  analogWrite(ENA, 200);

 

  delay(3000);

 

  // Stop

  digitalWrite(IN1, LOW);

  digitalWrite(IN2, LOW);

  analogWrite(ENA, 0);

 

  delay(1000);

 

  // Reverse

  digitalWrite(IN1, LOW);

  digitalWrite(IN2, HIGH);

  analogWrite(ENA, 150);

 

  delay(3000);

 

  // Stop

  digitalWrite(IN1, LOW);

  digitalWrite(IN2, LOW);

  analogWrite(ENA, 0);

 

  delay(1000);

}

6.5.9 Code Description

IN1 and IN2 control the direction of the motor.

ENA controls motor speed using PWM.

digitalWrite() determines the direction.

analogWrite() controls the PWM duty cycle.

6.5.10 Applications

DC motors are used in:

• Robots
• Conveyor systems
• Fans
• Pumps
• Automated machines
• Toy vehicles
• Electric vehicles
• Industrial equipment