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Motor Driver (L293D)

A dual H-bridge motor driver IC capable of driving two DC motors bidirectionally or one bipolar stepper motor.

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L293D IC

The L293D is an integrated circuit motor driver that can be used for simultaneous, bidirectional control of two DC motors. It contains two built-in H-bridges and internal flyback diodes to protect your microcontroller.

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Overview

Microcontrollers like the Arduino cannot output enough current to drive motors directly. The L293D acts as an amplifier: it takes low-current control signals from the Arduino and uses them to switch a higher-current power supply dedicated to the motors.

Pin Reference

(Note: Pin numbering starts top-left at the notch and goes down, then up the right side).

Pin	Type	Description
EN1,2	digital	Enable pin for Motor 1. High = ON, Low = OFF. (PWM for speed control).
IN1	digital	Input 1 for Motor 1 direction control.
OUT1	digital	Output 1. Connect to motor 1 terminal A.
GND1/2	power	Ground. Connect to Arduino GND and battery GND.
OUT2	digital	Output 2. Connect to motor 1 terminal B.
IN2	digital	Input 2 for Motor 1 direction control.
VCC2	power	Motor Power (Vs). Connect to battery positive (up to 36V).
VCC1	power	Logic Power (Vss). Connect to Arduino 5V.
IN4	digital	Input 4 for Motor 2 direction control.
OUT4	digital	Output 4. Connect to motor 2 terminal B.
GND3/4	power	Ground. Connect to Arduino GND and battery GND.
OUT3	digital	Output 3. Connect to motor 2 terminal A.
IN3	digital	Input 3 for Motor 2 direction control.
EN3,4	digital	Enable pin for Motor 2. (PWM for speed control).

Configurable Attributes

This component has no standard configurable attributes.

Working Principle (H-Bridge)

An H-Bridge allows voltage to be applied across a load in either direction.

• If IN1 is HIGH and IN2 is LOW, the motor spins Forward.
• If IN1 is LOW and IN2 is HIGH, the motor spins Backward.
• If both are LOW, the motor stops.
• Applying a PWM signal to EN1,2 pulses the power rapidly, changing the motor's average speed.

Wiring Diagram (Single Motor)

This diagram shows how to wire a single DC motor to the L293D.

Example Arduino Code

This code drives a single motor forward, then backward, then stops.

const int enA = 9;
const int in1 = 8;
const int in2 = 7;

void setup() {
  pinMode(enA, OUTPUT);
  pinMode(in1, OUTPUT);
  pinMode(in2, OUTPUT);
}

void loop() {
  // Full speed forward
  digitalWrite(in1, HIGH);
  digitalWrite(in2, LOW);
  analogWrite(enA, 255); 
  delay(2000);
  
  // Full speed backward
  digitalWrite(in1, LOW);
  digitalWrite(in2, HIGH);
  analogWrite(enA, 255);
  delay(2000);
  
  // Stop
  digitalWrite(in1, LOW);
  digitalWrite(in2, LOW);
  delay(2000);
}

Simulation Notes

• The L293D perfectly simulates H-bridge logic. If you wire the VCC2 pin incorrectly, the motors will not spin.
• The motors in the simulation will display their RPM, allowing you to visually verify speed control via PWM.

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