L293D Motor Driver

Article thumbnail


Controlling a motor from an Arduino using the L293D H-bridge

Driving a Motor with Arduino

A good way to control a motor is to use an H-bridge. This is a type of circuit that allows you to reverse the current flow of the motor, therefore giving you direction control.

An H-bridge contains four switches and a motor at the center, forming an H-like shape. Turning any two of the switches on reverses the motor's current, which can change its direction.

H-bridge direction control H-bridge direction control

The L293D has two of these H-bridges inside it, allowing you to control up to two DC motors or one stepper motor.

L293D Pinout

Pin Number Pin Name
1 Enable 1
2 Input 1
3 Output 1
6 Output 2
7 Input 2
8 VCC2
9 Enable 2
10 Input 3
11 Output 3
12 GND
14 Output 4
15 Input 4
6 VCC1

The pins with names containing the same numbers form a single channel in the L293D that can control one motor.

Each pin type has a specific function:

Controlling L293D

The Enable pins turn their motors on/off. A HIGH state enables the motor; a LOW state disables it. You can also send PWM signals to control motor speed. A duty cycle of 0% stops the motor; a duty cycle of 100% runs the motor at full speed.

The input pin pairs of the H-bridge control the direction of their motor. If input A is high and input B is low, the motor spins one direction. If input A is low and input B is high, the motor spins in the opposite direction. If the inputs' states are the same, the motor stops.

H-Bridge Control Summary
Input Motor Direction/Speed
Enable In A In B Stopped Direction 1 Direction 2 Varied Speed
0 X X
1 1 1
1 1 0
1 0 1
1 0 0


L293D schematic


// Define pin constants
#define EN  5
#define IN1 4
#define IN2 3

boolean isReversed = false;

void setup() {
  // Configure pins as output
  pinMode(EN,  OUTPUT);
  pinMode(IN1, OUTPUT);
  pinMode(IN2, OUTPUT);

void loop() {
  for (int i = 0; i < 256; i++) {
    // Increment the speed from 0 to 255
    setMotorSpeed(i, isReversed);

  delay(3000); // Run at full speed for 3 seconds

  for (int i = 255; i > 0; i--) {
    // Decrement the speed from 255 to 0
    setMotorSpeed(i, isReversed);

  // Stop the motor and wait a little bit
  isReversed = !isReversed; // Reverse the motor

// Motor control functions

void setMotorSpeed(int speed, boolean reverse) {
  // Set the speed of the motor.
  analogWrite(EN, speed);
  digitalWrite(IN1, reverse);
  digitalWrite(IN2, !reverse);

void stopMotor() {
  // Stop the motor.
  analogWrite(EN, 0);
  digitalWrite(IN1, LOW);
  digitalWrite(IN2, LOW);