On this tutorial, we will show you how to use the L293D DC motor controller with the Arduino. The L293D is a H Bridge type IC and can control DC motors up to 36V. For detailed specs, check the datasheet.

Let's take a look at the L293D pinout:

As shown in the picture above, it's possible to drive 2 motors with a single L293D, however the power supply has to be strong enough to provide enough current. Here we will demonstrate with just one motor. The following table shows how to make the motor turn clockwise and anti-clockwise:

For example, if the pins 1 and 7 are in HIGH state, and the pin 2 in the LOW, the motor will rotate clockwise. On the other hand, if the pins 1 and 2 are in HIGH, and the pin 7 in the LOW, the motor will turn to the other way.

With a push button, a 10Kohm resistor, a DC motor, a 9V battery, an Arduino and the L293D, let's make this circuit:

On this circuit, the 9V battery supply the energy to the DC motor. Be careful, check you motor datasheet before connect it to the circuit!

After that, open your Arduino IDE and upload this code:

int switchPin = 2; // switch input
int motor1Pin1 = 3; // pin 2 on L293D
int motor1Pin2 = 4; // pin 7 on L293D
int enablePin = 9; // pin 1 on L293D

void setup() {
    // set the switch as an input:
    pinMode(switchPin, INPUT);

    // set all the other pins you're using as outputs:
    pinMode(motor1Pin1, OUTPUT);
    pinMode(motor1Pin2, OUTPUT);
    pinMode(enablePin, OUTPUT);

    // set enablePin high so that motor can turn on:
    digitalWrite(enablePin, HIGH);
}

void loop() {
    // if the switch is high, motor will turn on one direction:
    if (digitalRead(switchPin) == HIGH) {
        digitalWrite(motor1Pin1, LOW); // set pin 2 on L293D low
        digitalWrite(motor1Pin2, HIGH); // set pin 7 on L293D high
    }
    // if the switch is low, motor will turn in the opposite direction:
    else {
        digitalWrite(motor1Pin1, HIGH); // set pin 2 on L293D high
        digitalWrite(motor1Pin2, LOW); // set pin 7 on L293D low
    }
}

Turn on your circuit and the motor will rotate to one direction. Press the button and the motor will rotate to the other side.

That it! Feel free to comment and post your thoughts. The Garage Lab is and open space to share knowledge and talk about electronics, open hardware, arduino and DIY stuff and hacking.

References:

http://luckylarry.co.uk/arduino-projects/control-a-dc-motor-with-ar...

http://arduino.cc/playground/Main/InterfacingWithHardware

http://www.datasheetcatalog.org/datasheet/stmicroelectronics/1330.pdf