//================================================================================ //
// Interruptions Arduino MEGA ATMEGA 2560
//================================================================================ //

#define F_CPU 16000000 UL

#include <avr/io.h>
#include <util/delay.h>

//============== Macro definitions for working with bits ======================== // 
#define set_bit(y, bit)(y |= (1 << bit))    // sets the x bit of the variable Y to 1
#define clear_bit(y, bit)(y &= ~(1 << bit)) // sets bit x of variable Y to 0
#define toggle_bit(y, bit)(y ^= (1 << bit)) // changes the logical state of bit x of variable Y
#define test_bit(y, bit)(y & (1 << bit))    // returns 0 or 1 depending on the bit reading
//================================================================================ //

// ISR(INT0_vect);
int main(void){
  Serial.begin(9600);
  clear_bit(DDRD, PD0); // set pin button as input
  set_bit(PORTD, PD0); // define button pin as HIGT for enable pull up resistor

  set_bit(DDRH, PH3); // set PH3 as input for led
  clear_bit(PORTH, PH3);  // turn of LED for default

  sei(); // habilita interrupções globais, ativando o bit I do SREG
  // set_bit(EICRA, ISC01); // enable request interruption for the falling edge
  // set_bit(EICRA, ISC11);
  set_bit(EIMSK, INT0); // enable int0 for external interruptions

  while(1){
    // Serial.print(test_bit(PIND, PD0));
  }

  Serial.end();

  return 0;
}

ISR(INT0_vect) {
  _delay_ms(100);
  if(test_bit(PIND, PD0)){
    Serial.print("@");
  }else{
    Serial.print("-");
  }
}