Codigo ejemplo:
 int Pin0 = 8;
 int Pin1 = 9;
 int Pin2 = 10;
 int Pin3 = 11;
 int _step = 0; 
 int pases=0;
 boolean dir = false;// change the direction of the motor
 void setup() 
 { 
  pinMode(Pin0, OUTPUT);  
  pinMode(Pin1, OUTPUT);  
  pinMode(Pin2, OUTPUT);  
  pinMode(Pin3, OUTPUT);  
  Serial.begin(9600);
 } 
   void loop() 
 { 
   for(pases=0;pases<4075;pases++){
     pas();
     delay(1);  // change this delay to control the speed of your
stepper, delay to 100 you can see the signal LEDs blinking.
   }
   delay(500);
 }
 void pas()
 {
   switch(_step){ 
    case 0: 
      digitalWrite(Pin0, LOW);  
      digitalWrite(Pin1, LOW); 
      digitalWrite(Pin2, LOW); 
      digitalWrite(Pin3, HIGH); 
    break;  
    case 1: 
      digitalWrite(Pin0, LOW);  
      digitalWrite(Pin1, LOW); 
      digitalWrite(Pin2, HIGH); 
      digitalWrite(Pin3, HIGH); 
    break;  
    case 2: 
      digitalWrite(Pin0, LOW);  
      digitalWrite(Pin1, LOW); 
      digitalWrite(Pin2, HIGH); 
      digitalWrite(Pin3, LOW); 
    break;  
    case 3: 
      digitalWrite(Pin0, LOW);  
      digitalWrite(Pin1, HIGH); 
      digitalWrite(Pin2, HIGH); 
      digitalWrite(Pin3, LOW); 
    break;  
    case 4: 
      digitalWrite(Pin0, LOW);  
      digitalWrite(Pin1, HIGH); 
      digitalWrite(Pin2, LOW); 
      digitalWrite(Pin3, LOW); 
    break;  
    case 5: 
      digitalWrite(Pin0, HIGH);  
      digitalWrite(Pin1, HIGH); 
      digitalWrite(Pin2, LOW); 
      digitalWrite(Pin3, LOW); 
    break;  
      case 6: 
      digitalWrite(Pin0, HIGH);  
      digitalWrite(Pin1, LOW); 
      digitalWrite(Pin2, LOW); 
      digitalWrite(Pin3, LOW); 
    break;  
    case 7: 
      digitalWrite(Pin0, HIGH);  
      digitalWrite(Pin1, LOW); 
      digitalWrite(Pin2, LOW); 
      digitalWrite(Pin3, HIGH); 
    break;  
    default: 
      digitalWrite(Pin0, LOW);  
      digitalWrite(Pin1, LOW); 
      digitalWrite(Pin2, LOW); 
      digitalWrite(Pin3, LOW); 
    break;  
  } 
  if(dir){     _step++; ;  }else{     _step--;   } 
  if(_step>7){     _step=0;   } 
  if(_step<0){     _step=7;   } 
 }



