Arduino: How to Control Dual DC Motors with L293D IC Motor Driver

In this tutorial, we will learn how to control two DC motors using the L293D Dual H-Bridge Motor Driver and an Arduino Uno. The L293D IC allows you to drive two motors independently in both forward and reverse directions — ideal for small robot car projects or any application requiring precise motor control.

Hardware Required

• Arduino Uno board
• L293D Dual H-Bridge Motor Driver IC
• 2 DC Motors
• Breadboard
• Jumper wires
• External battery pack (for motor power, e.g., 4.5V–9V)

About the L293D Motor Driver

The L293D is a dual-channel H-bridge motor driver IC that can control up to two DC motors or one stepper motor. It can deliver up to 600 mA per channel (maximum 1.2 A peak).

Each side of the chip controls one motor:

• Left side pins → Motor A
• Right side pins → Motor B

The IC has two separate power pins:

• Pin 8 (Vmotor): Motor power supply (up to 36V)
• Pin 16 (Vcc): Logic power supply (typically 5V)

Both grounds (Arduino and battery) must be connected together for proper operation.

Circuit

1. Motor Power: The motors are powered by an external battery pack connected to pin 8 (Vmotor) on the L293D. This ensures the Arduino does not have to supply motor current directly.
2. Logic Power: The 5V pin of the Arduino powers the L293D logic via pin 16 (Vcc).
3. Control Pins:
   • Arduino pins 2 and 3 control the left motor’s direction (forward/reverse).
   • Arduino pins 4 and 5 control the right motor’s direction.
4. Outputs: The outputs from the L293D (pins 3, 6, 11, and 14) connect directly to the two motors.
5. Common Ground: The battery pack’s ground and the Arduino’s ground are connected together to complete the circuit.

This configuration allows full forward and backward control for both DC motors.

Code

// Define motor control pins
const int leftForward = 2;
const int leftBackward = 3;
const int rightForward = 4;
const int rightBackward = 5;

void setup() {
  // Set all motor pins as outputs
  pinMode(leftForward, OUTPUT);
  pinMode(leftBackward, OUTPUT);
  pinMode(rightForward, OUTPUT);
  pinMode(rightBackward, OUTPUT);
}

void loop() {
  // Move both motors forward
  digitalWrite(leftForward, HIGH);
  digitalWrite(leftBackward, LOW);
  digitalWrite(rightForward, HIGH);
  digitalWrite(rightBackward, LOW);
  
  delay(2000); // Run forward for 2 seconds
  
  // Move both motors backward
  digitalWrite(leftForward, LOW);
  digitalWrite(leftBackward, HIGH);
  digitalWrite(rightForward, LOW);
  digitalWrite(rightBackward, HIGH);
  
  delay(2000); // Run backward for 2 seconds
  
  // Stop both motors
  digitalWrite(leftForward, LOW);
  digitalWrite(leftBackward, LOW);
  digitalWrite(rightForward, LOW);
  digitalWrite(rightBackward, LOW);
  
  delay(1000); // Pause before repeating
}

How It Works

1. The Arduino sends HIGH or LOW signals to the L293D input pins.
2. The L293D translates these signals into motor movement:
   • HIGH/LOW → Motor rotates forward
   • LOW/HIGH → Motor rotates backward
   • LOW/LOW → Motor stops
3. The external battery pack provides sufficient current for the motors, while the Arduino only controls the logic signals.

Important Notes

• Do not power motors directly from the Arduino 5V pin. Use an external power supply (batteries or adapter).
• Always connect all grounds (GNDs) together — Arduino, battery, and L293D.
• If motors draw more than 600 mA, use a stronger motor driver like L298N or a MOSFET-based H-bridge.

This setup is perfect for building a basic two-wheel robot car, where one motor controls each wheel. You can expand the project by adding sensors, Bluetooth, or infrared modules to automate the robot’s movements.