// Requires headers for AVR defines and ISR function
#include <avr/io.h>
#include <avr/interrupt.h>


// Define pins for switch the LED, plus the chosen interrupt for reacting to
#define INTERRUPT_PIN PCINT3  // This is PB3 per the schematic
#define INT_PIN PB3           // Interrupt pin of choice: PB3 (same as PCINT3) - Pin 2
#define OUT_PIN PB1           // PB1 - Pin 6

bool FIRE_FLAG;
int delaySet =2000; // delay time

/*
 * Alias for the ISR: "PCINT_VECTOR" (Note: There is only one PCINT ISR. 
 * PCINT0 in the name for the ISR was confusing to me at first, 
 * hence the Alias, but it's how the datasheet refers to it)
 */
#define PCINT_VECTOR PCINT0_vect      // This step is not necessary - it's a naming thing for clarity

// FYI: Variables used within ISR must be declared Volatile.
// static volatile byte LEDState; 


// The setup function runs only once when the ALU boots
void setup() {

    // Code here is the key piece of configuring and enabling the interrupt 

    cli();                            // Disable interrupts during setup
 
    PCMSK |= (3 << INTERRUPT_PIN);    // Enable interrupt handler (ISR) for our chosen interrupt pin (PCINT1/PB1/pin 6)

    GIMSK |= (1 << PCIE);             // Enable PCINT interrupt in the general interrupt mask

    pinMode(INT_PIN, INPUT);          // Set our interrupt pin as input

    sei();                            //last line of setup - enable interrupts after setup

    digitalWrite(OUT_PIN, HIGH);
    delay(1000);
    digitalWrite(OUT_PIN, LOW);
    delay(1000);

}


void loop() {
  // put your main code here, to run repeatedly:

  if (FIRE_FLAG == true){
    digitalWrite(OUT_PIN, HIGH);
    delay(delaySet);
    digitalWrite(OUT_PIN, LOW);
    delay(2000);
    FIRE_FLAG = false;
    }
  
}

ISR(PCINT_VECTOR)
{
  FIRE_FLAG = true;
}