/*

=== Could not get this to work, maybe it's a problem with
Wokwi and Timer1. Try breadboarding this...

Controlled by:
* TCCR1 (Timer/Counter1 Control Register)
* GTCCR (General Timer/Counter Control Register)
* OCR1A, OCR1C (Compare registers)
* TCNT1 (Timer/Counter1)
* TIMSK (Interrupt mask)
* TIFR (Interrupt flags)
*/


#define F_CPU 8000000UL
#include <avr/io.h>
#include <avr/interrupt.h>

#define LED_PIN PB1

void timer1_init(void) {
  TCCR1 = 0; // Normal mode

  // Prescaler = clk/64 → CS12=1, CS11=1, CS10=1 (binary 0b111)
  TCCR1 |= (1 << CS12) | (1 << CS11) | (1 << CS10);

  // Enable Timer1 overflow interrupt
  TIMSK |= (1 << TOIE1);

  // Clear counter
  TCNT1 = 0;
}

ISR(TIMER1_OVF_vect) {
  PORTB ^= (1 << LED_PIN); // Toggle LED on every overflow
}

int main(void) {
  DDRB |= (1 << LED_PIN);   // Set LED pin as output
  PORTB &= ~(1 << LED_PIN); // Ensure LED starts low

  timer1_init(); // Start Timer1
  sei();         // Enable global interrupts

  while (1) {
    // Nothing here — just wait for interrupt
  }
}