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/*
  Shift Register Example
  Turning on the outputs of a 74HC595 using an array

 Hardware:
 * 74HC595 shift register
 * LEDs attached to each of the outputs of the shift register

 */

//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;

//holders for infromation you're going to pass to shifting function
byte data;
byte dataArray[10];

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

  //Arduino doesn't seem to have a way to write binary straight into the code
  //so these values are in HEX.  Decimal would have been fine, too.
  dataArray[0] = 0xFF; //11111111
  dataArray[1] = 0xFE; //11111110
  dataArray[2] = 0xFC; //11111100
  dataArray[3] = 0xF8; //11111000
  dataArray[4] = 0xF0; //11110000
  dataArray[5] = 0xE0; //11100000
  dataArray[6] = 0xC0; //11000000
  dataArray[7] = 0x80; //10000000
  dataArray[8] = 0x00; //00000000
  dataArray[9] = 0xE0; //11100000

  //function that blinks all the LEDs
  //gets passed the number of blinks and the pause time
  blinkAll_2Bytes(2,500);
}

void loop() {

  for (int j = 0; j < 10; j++) {
    //load the light sequence you want from array
    data = dataArray[j];
    //ground latchPin and hold low for as long as you are transmitting
    digitalWrite(latchPin, 0);
    //move 'em out
    shiftOut(dataPin, clockPin, data);
    //return the latch pin high to signal chip that it
    //no longer needs to listen for information
    digitalWrite(latchPin, 1);
    delay(300);
  }
}



// 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´┐Ż
  //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);
}


//blinks the whole register based on the number of times you want to
//blink "n" and the pause between them "d"
//starts with a moment of darkness to make sure the first blink
//has its full visual effect.
void blinkAll_2Bytes(int n, int d) {
  digitalWrite(latchPin, 0);
  shiftOut(dataPin, clockPin, 0);
  shiftOut(dataPin, clockPin, 0);
  digitalWrite(latchPin, 1);
  delay(200);
  for (int x = 0; x < n; x++) {
    digitalWrite(latchPin, 0);
    shiftOut(dataPin, clockPin, 255);
    shiftOut(dataPin, clockPin, 255);
    digitalWrite(latchPin, 1);
    delay(d);
    digitalWrite(latchPin, 0);
    shiftOut(dataPin, clockPin, 0);
    shiftOut(dataPin, clockPin, 0);
    digitalWrite(latchPin, 1);
    delay(d);
  }
}

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