ArduinoShiftRegister

// use shift registers(74HC595) to control an insane amount of digital inputs.
// https://www.youtube.com/watch?v=nXl4fb_LbcI
#include <SPI.h>
byte Input, Output, Check=1;
int j;
void setup(){
  pinMode(13, OUTPUT);//clock
  pinMode(11, OUTPUT);//data
  pinMode(4, OUTPUT);//latch
  pinMode(2, INPUT);//Input from buttons


  
  
SPI.setBitOrder(MSBFIRST);
SPI.setDataMode(SPI_MODE0);
SPI.setClockDivider(SPI_CLOCK_DIV2);
SPI.begin();
  SPI.transfer(255);
  SPI.transfer(0);
  digitalWrite(4, HIGH);
  digitalWrite(4, LOW);
  Serial.begin(9600);
 attachInterrupt(0, pin_read, RISING); 
  
}//setup

void loop(){

}//loop


  void pin_read(){

    for(j=0; j<50; j++)
    delayMicroseconds(1000);

    Check=1;
    for(j=0; j<8; j++){
  SPI.transfer(Check);
  SPI.transfer(Output);
  digitalWrite(4, HIGH);
  digitalWrite(4, LOW);
  delayMicroseconds(500);
  if(digitalRead(2)==HIGH){
      if(bitRead(Output, j)==1)
      bitWrite(Output, j, 0);
      else
      bitWrite(Output, j, 1);
  }//dig check
  
  Check = Check<<1;
    }//j
    
  SPI.transfer(255);
  SPI.transfer(Output);
  digitalWrite(4, HIGH);
  digitalWrite(4, LOW);
 
 while(digitalRead(2)==HIGH){}

}//pin_read