/*
  AudioDiWhy Wokwi #questions — 12/23 at 6:21 PM
  An update, after screwing around with this more,
  I am finding all variables that I put in the sketch reset,
  not just volatile one.  It seems like the sketch is crashing
  the sim and then it starts again.

  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"

*****Depends on Bounce being unckecked*****
*/

#include <TinyDebug.h>
// not needed in wokwi
#include <avr/io.h>
#include <avr/interrupt.h>

#define INT0_VECTOR INT0_vect

const int BTN_PIN = PB2;
const int LED_PIN = PB0;

volatile int value = 0;
int oldValue = 0;

void setup()
{
  Debug.begin();
  pinMode(BTN_PIN, INPUT_PULLUP);
  pinMode(LED_PIN, OUTPUT);
  cli();                // Disable interrupts during setup
  GIMSK = 0b01000000;   // 9.3.2 GIMSK – General Interrupt Mask Register
  //GIFR  = 0b01000000; // 9.3.3 GIFR – General Interrupt Flag Register
  //PCMSK = 0b00000000; // 9.3.4 PCMSK – Pin Change Mask Register
  MCUCR = 0b00000010;   // Table 9-2. Interrupt 0 Sense Control, falling
  sei();                // enables interrupts
  Debug.println("Ready\n");
}

void loop()
{
  if (value != oldValue)  {
    oldValue = value;
    Debug.println(value);
    digitalWrite(LED_PIN, value % 2);
  }
}

ISR(INT0_VECTOR)
{
  value++;             // Increment volatile variable
}