DC motor control using L293D Motor Shield and Arduino

To use the library is fairly simple. Open a sketch and type in the following at the top in order to use the library functions. 

 #include <AFMotor.h>

After including the header file we have to create an object with some alias name. For DC motors we have to use the class AF_DCMotor to create a dc motor object. For example the following line create a DC motor object called motor. 

AF_DCMotor motor(1);

The motor object accepts two parameters which are the number(1, 2, 3 or 4) or the channel of the motor where the motor will be connected to. And the 2nd parameter is the frequency. The frequency setting for channel 1 and 2 are:

MOTOR12_64KHZ

or, MOTOR12_8KHZ

or, MOTOR12_2KHZ

or, MOTOR12_1KHZ

And the frequencies for channel 3 & 4 are: 

MOTOR34_64KHZ

or, MOTOR34_8KHZ

or, MOTOR34_1KHZ

 It is optional to specify the frequency parameter while creating the DC motor object. If we do not specify the frequency then the default frequency is 1KHz.

Once the DC object is created, we can use it's various methods. These methods are explained briefly below.

1. motor.setSpeed(parameter);

This setSpeed() method will set the speed of the DC motor which takes one parameter that ranges from 0(lowest speed) to maximum of 255(highest speed).

eg. motor.setSpeed(127);

2. motor.run(parameter)

This run() method will set the direction of rotation of the motor. It can take the parameters- FORWARD, BACKWARD, RELEASE

eg. motor.run(FORWARD)

Program code

The following program will move the DC motor attached to motor channel 1 of the motor shield either in forward, backward, accelerate, deaccelerate or stop according to command we send to the Arduino via serial port. If we send character 'f' then it will run the motor in forward direction, if we send character 'b' then the motor will run in backward direction, if we send 'a' then it will accelerate, if we send 'd' then the motor will deaccelerate and if we send 's' then the motor will stop spinning.

#include <AFMotor.h>

AF_DCMotor motor(1);

void setup(){
  mstop();
  Serial.begin(9600);
}

void loop(){
  if(Serial.available()){
      char cmd = Serial.read();
      switch(cmd){
        case 'f':
          forward();
          break;

        case 'b':
          backward();
          break;

        case 'a':
          accelerate();
          break;

        case 'd':
          deaccelerate();
          break;

        case 's':
          mstop();
          break;

        default:
          break;
      }
    }
}

void forward(){
  motor.setSpeed(200);
  motor.run(FORWARD);
  }

void backward(){
  motor.setSpeed(200);
  motor.run(BACKWARD);
  }

void accelerate(){
  motor.run(FORWARD); 

    uint8_t i;

    for (i=0; i<255; i++){
    motor.setSpeed(i);  
    delay(10);
    }
}

void deaccelerate(){
  motor.run(FORWARD); 

  uint8_t i;
  for(i=255; i!= 0; i--){
    motor.setSpeed(i);  
    delay(10);
    }
}

void mstop(){
   motor.run(RELEASE);
  } 

In conclusion, controlling a DC motor using an L 293D motor shield and an Arduino is a straightforward and convenient way to control motors in a variety of applications. With just a few simple components and a little programming, we can create sophisticated control systems that use DC motors. Whether you are building a robotic system or automating a process, the L293D motor shield and the Arduino are powerful tools that can help you achieve your goals.

In the above code we have used motor shield library, for writing program for motor shield without library see the tutorial DC motor Control using Arduino USART serial communication.

References:

• https://github.com/adafruit/Adafruit_Motor-Shield-v1