Logos Electromechanical

 //Pin connected to ST_CP of 74HC595
int latchPin = 7;
//Pin connected to SH_CP of 74HC595
int clockPin = 13;
////Pin connected to DS of 74HC595
int dataPin = 11;

void setup() {
  //set pins to output because they are addressed in the main loop
  pinMode(latchPin, OUTPUT);
  Serial.begin(9600);
}

void loop() {

  if (Serial.available() > 3) {

    //preparamos para enviar datos
    digitalWrite(latchPin, 0); 
    digitalWrite(8, HIGH); // Deactivates master reset ESTO VA FUERA DEL LOOP O NO?

    //contamos los numeros de shift registers conectados 
    for (int i=0 ; i < 4; i++)
    {
      //byte a=(byte) Serial.read() - '0';
      //leimos el contenido del puerto serial
      byte a=(byte) Serial.read();

      //move 'em out
      shiftOut(dataPin, clockPin, a);
      //digitalWrite(latchPin, 1);
      Serial.println(a);
    }

    digitalWrite(latchPin, 1);
  }
}

// the heart of the program
void shiftOut(int myDataPin, int myClockPin, byte myDataOut) {
  // This shifts 8 bits out MSB first, 
  //on the rising edge of the clock,
  //clock idles low

  //internal function setup
  int i=0;
  int pinState;
  pinMode(myClockPin, OUTPUT);
  pinMode(myDataPin, OUTPUT);

  //clear everything out just in case to
  //prepare shift register for bit shifting
  digitalWrite(myDataPin, 0);
  digitalWrite(myClockPin, 0);

  //for each bit in the byte myDataOut�
  //NOTICE THAT WE ARE COUNTING DOWN in our for loop
  //This means that %00000001 or "1" will go through such
  //that it will be pin Q0 that lights. 
  for (i=7; i>=0; i--)  {
    digitalWrite(myClockPin, 0);

    //if the value passed to myDataOut and a bitmask result 
    // true then... so if we are at i=6 and our value is
    // %11010100 it would the code compares it to %01000000 
    // and proceeds to set pinState to 1.
    if ( myDataOut & (1<<i) ) {
      pinState= 1;
    }
    else {  
      pinState= 0;
    }

    //Sets the pin to HIGH or LOW depending on pinState
    digitalWrite(myDataPin, pinState);
    //register shifts bits on upstroke of clock pin  
    digitalWrite(myClockPin, 1);
    //zero the data pin after shift to prevent bleed through
    digitalWrite(myDataPin, 0);
  }

  //stop shifting
  digitalWrite(myClockPin, 0);
}