#define EICRA_BASEADDR 0x69
#define EIMSK_BASEADDR 0x3D
#define EIFR_BASEADDR  0x3C
#define SREG_BASEADDR  0x5F

#define ISC00   0
#define ISC01   1
#define I       7
#define INT0    0

#define _EICRA  (*(volatile uint8_t *)EICRA_BASEADDR)
#define _EIMSK  (*(volatile uint8_t *)EIMSK_BASEADDR)
#define _EIFR   (*(volatile uint8_t *)EIFR_BASEADDR)
#define _SREG   (*(volatile uint8_t *)SREG_BASEADDR)

void EXTI_Init(void) {
  // Disable global interrupts while configuring
  _SREG &= ~(1 << I);             // Clear I bit in SREG to disable global interrupts

  // Configure INT0 for rising edge trigger
  _EICRA |= (1 << ISC01) | (1 << ISC00);   // Set ISC01 and ISC00 for rising edge
  _EIMSK |= (1 << INT0);                   // Enable INT0 external interrupt
  
  // Set PD2 (INT0) as input and enable internal pull-up if needed
  DDRD &= ~(1 << PD2);              // Set PD2 as input
  PORTD |= (1 << PD2);              // Enable internal pull-up (if button connects to GND)
  
  // Re-enable global interrupts
  _SREG |= (1 << I);                // Set I bit in SREG to enable global interrupts
}

void setup() {
  Serial.begin(9600);
  EXTI_Init();                      // Initialize EXTI once during setup
}

void loop() {
  // Main code can run here
}

// ISR for INT0 interrupt
ISR(INT0_vect) {
  Serial.println("Interrupt occurred on INT0");

  // Clear any pending interrupt flags for INT0 (if necessary)
  _EIFR |= (1 << INTF0);            // Write 1 to clear INT0 flag in EIFR
}