//https://docs.wokwi.com/parts/wokwi-attiny85   simulate ATTINY85 on wokwi
//https://wokwi.com/projects/317140124437578305  get interrupts working
// https://wokwi.com/projects/318885209198035539  debounce function.
// https://thewanderingengineer.com/2014/08/11/pin-change-interrupts-on-attiny85/ datasheet attiny85 ints.
//https://electronics.stackexchange.com/questions/264434/attiny85-interrupt-confusion "only PB2 on attiny85 can be used to trap edge changes"
#include <TinyDebug.h>
//#include <avr/io.h>
//#include <avr/interrupt.h>


#define clockin PB2    //use digital I/O pin PB1 (pin 6 of IC) for input
#define INT0_VECTOR INT0_vect 
#define LED PB0

volatile byte x = 0;
byte oldx = 0;

const int debounceDelay = 10; // milliseconds to wait until button input stable *



void setup() {
    pinMode(clockin, INPUT_PULLUP);   // Set our interrupt pin as input with a pullup   
    pinMode(LED, OUTPUT);  //PB0 is GPIO output
    
     

    cli();                            // Disable interrupts during setup
 
    PCMSK = 0b00000100;  //enable PB2/PCINT2 as our interrupt pin.

    GIMSK = 0b01000000;  // enable ext pin interrupts; enable pin changes to be treated as interrupts.
    
    MCUCR = 0b00000010; // int rising fall only. In wiwok unclick "bounce" 

  
    sei();      
    Debug.begin();  
  //Debug.println("you are beginning the sketch");
 
 
}

void loop() {
 
 //display value and light LED
 if (x != oldx)   {
    oldx = x;
    Debug.println(x);
    digitalWrite(LED, x % 2);
    if (x == 4) {
    x = 0;
    }
  }
}

ISR(INT0_VECTOR) {
             
      x++;
 
}