//Pin connected to ST_CP of 74HC595
int latchPin = 8;
//Pin connected to SH_CP of 74HC595
int clockPin = 12;
////Pin connected to DS of 74HC595
int dataPin = 11;
// variable tipo char para obtener que slide se esta usando en el proccesing
char res;
//variables donde se guardan el valor que indica cada slide
int encendido=128, apagado=128;
const int MAXLED = 8;
// arreglo de 8 LEDs, desde el pin 2 hasta el pin 9
int led[MAXLED] = {1,2,4,8,16,32,64,128};


void setup() {
  //set pins to output so you can control the shift register
  pinMode(latchPin, OUTPUT);
  pinMode(clockPin, OUTPUT);
  pinMode(dataPin, OUTPUT);
   for (int i=0; i<MAXLED; i++)
   pinMode(led[i], OUTPUT);
   Serial.begin(9600);
}

void loop() {
  // count from 0 to 255 and display the number
  // on the LEDs

 for (int i=0; i<MAXLED; i++) {
    leerDatos();
   // take the latchPin low so
    // the LEDs don't change while you're sending in bits:
    digitalWrite(latchPin, LOW);
    delay(apagado);


    // shift out the bits:
    shiftOut(dataPin, clockPin, MSBFIRST,led[i]);

    //take the latch pin high so the LEDs will light up:
    digitalWrite(latchPin, HIGH);
    // pause before next value:
    delay(encendido);
 }

 for (int i=MAXLED-2; i>0; i--) {
   leerDatos();
    // take the latchPin low so
    // the LEDs don't change while you're sending in bits:
    digitalWrite(latchPin, LOW);
    delay(apagado);
    // shift out the bits:
    shiftOut(dataPin, clockPin, MSBFIRST,led[i]);

    //take the latch pin high so the LEDs will light up:
    digitalWrite(latchPin, HIGH);
    // pause before next value:
    delay(encendido);
 }

}

 void leerDatos(){
  if (Serial.available()>0) {
    res=Serial.read();
    if (res=='e') {
      encendido = Serial.read();
    }
    else if (res=='a') {
      apagado = Serial.read();
    }

  }
}