//  Name    : shiftIn Example 2.2                               //
//  Author  : Carlyn Maw                                        //
//  Date    : 25 Jan, 2007                                      //
//  Version : 1.0                                               //
//  Notes   : Code for using a CD4021B Shift Register       //
//          :                                                   //

//define where your pins are
int latchPin = 8;
int dataPin = 9;
int clockPin = 7;

//Define variables to hold the data
//for each shift register.
//starting with non-zero numbers can help
byte switchVar1 = 72;  //01001000
byte switchVar2 = 159; //10011111

//define an array that corresponds to values for each
//of the first shift register's pins
char note2sing[] = {
  'C', 'd', 'e', 'f', 'g', 'a', 'b', 'c'};

//define an array that has a place for the values of
//pins 1-7 (not 0) of the second shift register's
//pins. Not 0 because that will be used as a flag value
byte settingVal[] = {
  0, 0, 0, 0, 0, 0, 0};  

//a flag varible used to track whether the program
//is in a setting update mode or not
byte settingSwitch = 0;  

void setup() {
  //start serial

  //define pin modes
  pinMode(latchPin, OUTPUT);
  pinMode(clockPin, OUTPUT);
  pinMode(dataPin, INPUT);


void loop() {

  //Pulse the latch pin:
  //set it to 1 to collect parallel data
  //set it to 1 to collect parallel data, wait
  //set it to 0 to transmit data serially  

  //while the shift register is in serial mode
  //collect each shift register into a byte
  //the register attached to the chip comes in first
  switchVar1 = shiftIn(dataPin, clockPin);
  switchVar2 = shiftIn(dataPin, clockPin);

  //Print out the results.
  //leading 0's at the top of the byte
  //(7, 6, 5, etc) will be dropped before
  //the first pin that has a high input
  Serial.println(switchVar1, BIN);
  Serial.println(switchVar2, BIN);

  //This for-loop steps through the byte
  //bit by bit which holds the shift register data
  //and if it was high (1) then it prints
  //the corresponding location in the array
  for (int n=0; n<=7; n++)
    //so, when n is 3, it compares the bits
    //in switchVar1 and the binary number 00001000
    //which will only return true if there is a
    //1 in that bit (ie that pin) from the shift
    if (switchVar1 & (1 << n) ){
      //print the value of the array location

//This is a away to examine the whole
//byte at once and create combinations
//of settings.

//By passing the switchVar1 variable to
//a "switch" statement and comparing it against
//a set nemerical value (written in binary)
//you can create special cases

  switch (switchVar1) {
  case B00101010:
    Serial.println("D minor");
  case B00010101:
    Serial.println("C major");
  case B01010100:
    Serial.println("E minor");
  case B00101001:
    Serial.println("F major");
  case B01010010:
    Serial.println("G major");
  case B00100101:
    Serial.println("A minor");
  case B01001010:
    Serial.println("B diminished");
    // if nothing else matches, do the default
    Serial.println("Play It, Joe");

// This is a more complicated behavior

//If the switch attached to pin 7 is High
  if (switchVar2 & (1 << 7) ){
    //print"Check, Check" to let us know the settings are being updated"
    Serial.println("Check, Check");
    //set a flag variable to let the progam know the settings are being updated
    settingSwitch = 1;

    //While the switch attached to seven is high,
    //take the bottom 7 bits and load them into
    //an array for easy access later.
    for (int v=6; v>=0; v--)
      if (switchVar2 & (1 << v) ){
        settingVal[v] = 1;
      else {
        settingVal[v] = 0;
  //if the switch is low
  else {
    //and if it was high the very last time it came through
    //this if statement (indicated by the settingSwitch variable still
    //set to "1")
    if (settingSwitch) {
      //turn off the settingSwitch variable

      //Print out the current settings

      for (int s=0; s<=6; s++)

      //Print out the setting names
      //this is being done as a case statement because
      //there weren't built in string arrays yet
      //in Arduino as of Feb. 2007
        switch (s) {
        case 0:
        case 1:
          Serial.print("Octave Shift");
        case 2:
        case 3:
        case 4:
        case 5:
        case 6:
          // if nothing else matches, do the default
          Serial.println("Not Defined");

        //Print Status
        if (settingVal[s]) {
          Serial.print(" On");
        else {
          Serial.print(" Off") ;      

         //white space


//white space
//delay so all these print satements can keep up.


//------------------------------------------------end main loop

////// ----------------------------------------shiftIn function
///// just needs the location of the data pin and the clock pin
///// it returns a byte with each bit in the byte corresponding
///// to a pin on the shift register. leftBit 7 = Pin 7 / Bit 0= Pin 0
byte shiftIn(int myDataPin, int myClockPin) {
  int i;
  int temp = 0;
  int pinState;
  byte myDataIn = 0;

  pinMode(myClockPin, OUTPUT);
  pinMode(myDataPin, INPUT);
//we will be holding the clock pin high 8 times (0,..,7) at the
//end of each time through the for loop

//at the begining of each loop when we set the clock low, it will
//be doing the necessary low to high drop to cause the shift
//register's DataPin to change state based on the value
//of the next bit in its serial information flow.
//The register transmits the information about the pins from pin 7 to pin 0
//so that is why our function counts down
  for (i=7; i>=0; i--)
    digitalWrite(myClockPin, 0);
    temp = digitalRead(myDataPin);
    if (temp) {
      pinState = 1;
      //set the bit to 0 no matter what
      myDataIn = myDataIn | (1 << i);
    else {
      //turn it off -- only necessary for debuging
     //print statement since myDataIn starts as 0
      pinState = 0;

    //Debuging print statements
    //Serial.print("     ");
    //Serial.println (dataIn, BIN);

    digitalWrite(myClockPin, 1);

  //debuging print statements whitespace
  //Serial.println(myDataIn, BIN);
  return myDataIn;