#include <AccelStepper.h>

#define HALFSTEP 8       // To know about HalfStep Stepper Motor plzz check the above mentioned link

// Motor pin definitions
#define motorPin1  8     // IN1 on the ULN2003 driver 1
#define motorPin2  9     // IN2 on the ULN2003 driver 1
#define motorPin3  10    // IN3 on the ULN2003 driver 1
#define motorPin4  11    // IN4 on the ULN2003 driver 1
boolean dir = true;    // To check whether its moving clockwise or anti-clockwise
                       //If true then clockwise ....else anti-clockwise 
// Initialize construtor with pin sequence IN1-IN3-IN2-IN4 for using the AccelStepper with 28BYJ-48
AccelStepper stepper1(HALFSTEP, motorPin1, motorPin3, motorPin2, motorPin4);

void setup() {
  stepper1.setMaxSpeed(1000);    // 1000 coz....greater than 1000 is unreliable .....as told on the info page
  stepper1.setAcceleration(1000);
  stepper1.setSpeed(1000);
  stepper1.moveTo(4096); // 4096 steps for 1 rotation in 28BYJ-48 – 5V Stepper Motor
}//--(end setup )---

void loop() {

  //Change direction when the stepper reaches the target position
  if (stepper1.distanceToGo() == 0)
  {
    if(dir == true)
    {
      dir = !dir;             // This line inverts the value of 'dir' and stores on count itself
      stepper1.move(-4096);   //Negative sign signifies anti-clockwise direction
    }
   if(dir == false)           //Does just the opposite of the above
    {
      dir = !dir;
      stepper1.move(4096);
    }
  }
  
      stepper1.run();        // run the stepper to the destined position
      //NOTE:- Whenever the run() is called the stepper is moved only 1 step to the direction assigned....so its important to call it every instance....more checking and looping before the run()is called... slows down the actual speed set initially 
}