Arduino L293D Motor Driver Shield Tutorial

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Overview

In this tutorial, you will learn how to drive DC, stepper and servo motors using an Arduino L293D motor driver shield.

What You Will Learn

• General information about DC motors
• Introduction to L293D motor shield
• Driving DC, Servo & Stepper motors

Motors & Drivers

Motors are an inseparable part of many robotics and electronics projects and have different types you can use depending on their application. Here is some information about different types of the motors:

DC Motors: DC motor is the most common type of engine that can be used for many applications. We can see it in remote control cars, robots, and etc. This motor has a simple structure. It will start rolling by applying proper voltage to its ends and change its direction by switching voltage polarity. DC motors speed is directly controlled by the applied voltage. When The voltage level is less than the maximum tolerable voltage, the speed would decrease.

Stepper Motors: In some projects such as 3D printers, scanners and CNC machines we need to know motor spin steps accurately. In these cases, we use Stepper motors. Stepper motor is an electric motor that divides a full rotation into a number of equal steps. The amount of rotation per step is determined by the motor structure. These motors have a very high accuracy.

Servo Motors: Servo motor is a simple DC motor with a position control service. By using a servo you will be able to control the amount of shafts rotation and move it to a specific position. They usually have a small dimension and are the best choice for robotic arms.

But we can’t connect these motors to microcontrollers or controller board such as Arduino directly in order to control them since they possibly need more current than a microcontroller can drive so we need drivers. The driver is an interface circuit between the motor and controlling unit to facilitate driving. Drives come in many different types. In this instruction, you learn to work on the L293D motor shield.

L293D shield is a driver board based on L293 IC, which can drive 4 DC motors and 2 stepper or Servo motors at the same time.

Each channel of this module has the maximum current of 1.2A and doesn’t work if the voltage is more than 25v or less than 4.5v. So be careful with choosing the proper motor according to its nominal voltage and current. For more features of this shield let’s mention compatibility with Arduini UNO and MEGA, electromagnetic and thermal protection of motor and disconnecting circuit in case of unconventional voltage raise.

How to Use Arduino L293D Motor Driver Shield?

While using this shield 6 analog Pins (which can be used as digital pins too), pin 2 and pin 13 of arduino are free.

In the case of using Servo motor, pins 9, 10, 2 are in use.

In the case of using DC motor, pin11 for #1, pin3 for #2, pin5 for #3, pin6 for #4 and pins 4, 7, 8 and 12 for all of them are in use.

In the case of using Stepper motor, pins 11 and 3 for #1, pins 5 and 6 for #2 and pins 4, 7, 8 and 12 for all of them are in use.

You can use free pins by wired connections.

If you are applying separate power supply to Arduino and shield, make sure you have disconnected the jumper on the shield.

Driving DC Motor

#include <AFMotor.h> 

The Library you need to control the motor:

AF_DCMotor motor(1, MOTOR12_64KHZ)

Defining the DC motor you are using.

The first argument stands for the number of the motors in the shield and the second one stands for the motor speed control frequency. The second argument can be MOTOR12_2KHZ, MOTOR12_8KHZ, MOTOR12_8KHZ, and MOTOR12_8KHZ for motors number 1 and 2, and it can be MOTOR12_8KHZ, MOTOR12_8KHZ, and MOTOR12_8KHZ for motors number 3 and 4. And if it left unchecked, it will be 1KHZ by default.

motor.setSpeed(200);

Defining the motor speed. It can be set from 0 to 255.

void loop() { 
motor.run(FORWARD);       
delay(1000); 
motor.run(BACKWARD);      
delay(1000);  
motor.run(RELEASE);       
delay(1000); 
}

Function motor.run() specifies the motor’s motion status. The status can be FORWARD, BACKWARD, and RELEASE. RELEASE is the same as the brake but it may take some time until the motor’s full stop.

It is recommended to solder a 100nF capacitor to each motor pins to reduce noise.

Driving Servo Motor

Arduino IDE library and examples are suitable for driving a Servo motor.

#include <servo.h> 

The library you need for driving the Servo motor

Servo myservo;

Defining a Servo motor object.

void setup() 
{ 
 myservo.attach(9);   
}

Determine the pin connecting to Servo.(pin 9 for sevo #1 and pin 10 for servo #2)

void loop()  
{  
 myservo.write(val);                   
 delay(15);                            
} 

Determine the amount of motor rotation. Between 0 to 360 or 0 to 180 according to motor type.

Driving Stepper Motor

#include <AFMotor.h> 

Determine the library you need

 AF_Stepper motor(48, 2);

Defining a Stepper motor object. The first argument is the motor step resolution. (for example, if your motor has the precision of 7.5 deg/step, it means the motor step resolution is. The second argument is the number of the Stepper motor connected to the shield.

void setup() { 
 motor.setSpeed(10);   
 motor.onestep(FORWARD, SINGLE);  
 motor.release(); 
 delay(1000); 
} 
void loop() { 
 motor.step(100, FORWARD, SINGLE);  
 motor.step(100, BACKWARD, SINGLE);
 motor.step(100, FORWARD, DOUBLE);  
 motor.step(100, BACKWARD, DOUBLE);
 motor.step(100, FORWARD, INTERLEAVE);  
 motor.step(100, BACKWARD, INTERLEAVE);  
 motor.step(100, FORWARD, MICROSTEP);  
 motor.step(100, BACKWARD, MICROSTEP);  
}

Determine motor speed in rpm.The first argument is the amount of step needed to move, the second one is to determine direction (FORWARD or BACKWARD), and the third argument determines the steps type: SINGLE (Activate a coil), DOUBLE (Activate two coils for more torque), INTERLEAVED (Continuous change in the number of coils from one to two and vice versa to double precision, however, in this case, the speed is halved), and MICROSTEP (Changing the steps is done slowly for more precision. In this case, the torque is lower).By default, when the motor stops moving, it maintains its status.You must use the function motor.release() to release the motor.

Related Projects:

• L293D: Theory, Diagram, Simulation & Pinout
• The Beginner’s Guide To Control Motors by Arduino & L293D

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