/*
  74HC595 Arduino Shift Register example for Wokwi
  Copyright (C) 2021, Uri Shaked
  
  explanation  to control 8 leds we require 9 conections one is comman cathod and another 8 anode but here 
  ic 74hc595 uses three pins from micro controller  and alternatly glow red and green led .this is called multiplexing or charliplexing
  ic is known as shift rtagister. 
  you can add one more ic to connect 8 more leds but pin 2,3,4 be connected to parrallel
 
 https://lastminuteengineers.com/74hc595-shift-register-arduino-tutorial/#:~:text=The%20first%20one%20is%20called%20the
 
  License: MIT.
*/

const int dataPin = 2;   /* DS */
const int clockPin = 3;  /* SHCP */
const int latchPin = 4;  /* STCP */

void setup() {
  pinMode(dataPin, OUTPUT);
  pinMode(clockPin, OUTPUT);
  pinMode(latchPin, OUTPUT);
}

int pattern = 0b10101010;
void loop() {
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, LSBFIRST, pattern);
  digitalWrite(latchPin, HIGH);
  delay(2000);
  pattern = ~pattern; // Invert the pattern
}