/*

  ######################################################################
  ||                                                                  ||
  ||        Title: Dual One-by-One on (2) 595 Shift Registers         ||
  ||                           Name: GC1CEO                           ||
  ||                         Date: 09/18/2024                         ||
  ||                                                                  ||
  ||                          Adapted from:                           ||
  ||                  shiftOutCode, Dual One By One                   ||
  ||                    By: Carlyn Maw, Tom Igoe                      ||
  ||                        Date: 25 Oct, 2006                        ||
  ||                                                                  ||
  ||                           Description:                           ||
  ||                                                                  ||
  ||Individual LEDs are lit one by one in opposing directions and back||
  ||  followed by a blinking animation and the cycle repeats itself.  ||
  ||                                                                  ||
  ######################################################################

*/

//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;
////Pin connected to inverted MR / SRCLR (Master Reset / Serial Register Clear) of 74HC595
int resetPin = 10;
////Pin connected to inverted OE (Output Enable) of 74HC595
int oePin = 9;
// delay between each number (in ms)
int delayTime = 200;
//holder for information 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);
  pinMode(clockPin, OUTPUT);
  pinMode(dataPin, OUTPUT);
  pinMode(resetPin, OUTPUT);
  pinMode(oePin, OUTPUT);

  // Set reset to HIGH (to not reset) and oe to LOW to enable output
  digitalWrite(resetPin, HIGH);
  digitalWrite(oePin, LOW);
}
void loop() {
  //function that blinks all the LEDs
  //gets passed the number of blinks and the pause time
  blinkAll_2Bytes(1, 500);
  // light each pin one by one using a function A
  for (int j = 0; j < 8; j++) {
    //ground latchPin and hold low for as long as you are transmitting
    digitalWrite(latchPin, 0);
    //red LEDs
    lightShiftPinA(7 - j);
    //green LEDs
    lightShiftPinA(j);
    //return the latch pin high to signal chip that it
    //no longer needs to listen for information
    digitalWrite(latchPin, 1);
    delay(delayTime);
  }
  // light each pin one by one using a function A
  for (int j = 0; j < 8; j++) {
    //ground latchPin and hold low for as long as you are transmitting
    digitalWrite(latchPin, 0);
    //red LEDs
    lightShiftPinB(j);
    //green LEDs
    lightShiftPinB(7 - j);
    //return the latch pin high to signal chip that it
    //no longer needs to listen for information
    digitalWrite(latchPin, 1);
    delay(delayTime);
  }
}
//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;
  //move 'em out
  shiftOut(dataPin, clockPin, pin);
}
//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;
  }
  //move 'em out
  shiftOut(dataPin, clockPin, pin);
}
// 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&#xFFFD;
  //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 both registers 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);
  }
}