const int clockPin = 12;

const int dataPin = 11;

  digitalWrite(latchPin, LOW);

  digitalWrite(latchPin, HIGH);

const int latchPin = 8;

const int clockPin = 11;

const int dataPin = 12;

[@

/*

  Shift Register Example
 for 74HC595 shift register

 This sketch turns reads serial input and uses it to set the pins
 of a 74HC595 shift register.

 Hardware:
 * 74HC595 shift register attached to pins 2, 3, and 4 of the Arduino,
 as detailed below.
 * LEDs attached to each of the outputs of the shift register

 Created 22 May 2009
 Created 23 Mar 2010
 by Tom Igoe

 */

//Pin connected to latch pin (ST_CP) of 74HC595 const int latchPin = 4; //Pin connected to clock pin (SH_CP) of 74HC595 const int clockPin = 3; ////Pin connected to Data in (DS) of 74HC595 const int dataPin = 2;

  pinMode(dataPin, OUTPUT);  

  Serial.begin(9600);
  Serial.println("reset");

  if (Serial.available() > 0) {
    // ASCII '0' through '9' characters are
    // represented by the values 48 through 57.
    // so if the user types a number from 0 through 9 in ASCII, 
    // you can subtract 48 to get the actual value:
    int bitToSet = Serial.read() - 48;

  // write to the shift register with the correct bit set high:
    registerWrite(bitToSet, HIGH);

// This method sends bits to the shift register:

void registerWrite(int whichPin, int whichState) { // the bits you want to send

  byte bitsToSend = 0;

  // turn off the output so the pins don't light up
  // while you're shifting bits:

  // turn on the next highest bit in bitsToSend:
  bitWrite(bitsToSend, whichPin, whichState);

  // shift the bits out:
  shiftOut(dataPin, clockPin, MSBFIRST, bitsToSend);

    // turn on the output so the LEDs can light up:
  digitalWrite(latchPin, LOW);

  pinMode(clockPin, OUTPUT);
  pinMode(dataPin, OUTPUT);

  digitalWrite(latchPin, LOW);

  shiftOut(dataPin, clockPin, MSBFIRST, pin);   

  digitalWrite(latchPin, HIGH);

  digitalWrite(latchPin, LOW);

  shiftOut(dataPin, clockPin, MSBFIRST, pin);   

  digitalWrite(latchPin, HIGH);

  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 0);
  digitalWrite(latchPin, HIGH);

    digitalWrite(latchPin, LOW);
    shiftOut(dataPin, clockPin, MSBFIRST, 255);
    digitalWrite(latchPin, HIGH);

    digitalWrite(latchPin, LOW);
    shiftOut(dataPin, clockPin, MSBFIRST, 0);
    digitalWrite(latchPin, HIGH);

Back to ShiftOut Tutorial

//**************************************************************//
//  Name    : shiftOutCode, One By One                          //
//  Author  : Carlyn Maw, Tom Igoe                           //
//  Date    : 25 Oct, 2006                                      //
//  Version : 1.0                                               //
//  Notes   : Code for using a 74HC595 Shift Register           //
//          : to count from 0 to 255                            //
//****************************************************************

//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;

//holder for infromation you're going to pass to shifting function
byte data = 0; 



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

}

void loop() {

  //function that blinks all the LEDs
  //gets passed the number of blinks and the pause time
  blinkAll(1,500); 

 // light each pin one by one using a function A
  for (int j = 0; j < 8; j++) {
    lightShiftPinA(j);
    delay(1000);
  }

  blinkAll(2,500);  

 // light each pin one by one using a function A
  for (int j = 0; j < 8; j++) {
    lightShiftPinB(j);
    delay(1000);
  } 

}

//This function uses bitwise math to move the pins up
void lightShiftPinA(int p) {
  //defines a local variable
  int pin;

  //this is line uses a bitwise operator
  //shifting a bit left using << is the same
  //as multiplying the decimal number by two. 
  pin = 1<< p;

  //ground latchPin and hold low for as long as you are transmitting
  digitalWrite(latchPin, 0);
  //move 'em out
  shiftOut(dataPin, clockPin, pin);   
  //return the latch pin high to signal chip that it 
  //no longer needs to listen for information
  digitalWrite(latchPin, 1);

}

//This function uses that fact that each bit in a byte
//is 2 times greater than the one before it to
//shift the bits higher
void lightShiftPinB(int p) {
  //defines a local variable
  int pin;

  //start with the pin = 1 so that if 0 is passed to this
  //function pin 0 will light. 
  pin = 1;

  for (int x = 0; x < p; x++) {
    pin = pin * 2; 
  }

  //ground latchPin and hold low for as long as you are transmitting
  digitalWrite(latchPin, 0);
  //move 'em out
  shiftOut(dataPin, clockPin, pin);   
  //return the latch pin high to signal chip that it 
  //no longer needs to listen for information
  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);
}


//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(int n, int d) {
  digitalWrite(latchPin, 0);
  shiftOut(dataPin, clockPin, 0);
  digitalWrite(latchPin, 1);
  delay(200);
  for (int x = 0; x < n; x++) {
    digitalWrite(latchPin, 0);
    shiftOut(dataPin, clockPin, 255);
    digitalWrite(latchPin, 1);
    delay(d);
    digitalWrite(latchPin, 0);
    shiftOut(dataPin, clockPin, 0);
    digitalWrite(latchPin, 1);
    delay(d);
  }
}