#include <Stepper.h>
const int stepsPerRevolution = 76;
Stepper myStepper (stepsPerRevolution, 8,9,10,11); 

const int pot = A0;
const int button = 2;
int speed = 50;

bool start_position=LOW; 
bool current_position=LOW;
bool rotate = true;

void setup () 
{ 
  Serial.begin (9600);
  pinMode(button, INPUT);
}

void loop () 
{
  debounce();
  if(current_position != start_position)
  {
    speed = map(analogRead(pot),0,1023,10,1000);
    myStepper.setSpeed (speed);

    if(rotate)
    {
      Serial.println ( "Move right"); 
      myStepper.step (stepsPerRevolution); 
      delay(1000);
      rotate = false;
    }
    else 
    {
      Serial.println ( "Move left"); 
      myStepper.step (-stepsPerRevolution);
      delay(1000);
      rotate = true;
    }
  }
  start_position = current_position;  
}

void debounce()
{
  current_position = digitalRead(button);
  if (current_position != start_position)
  {
    delay(5);
    current_position = digitalRead(button);
  }
}