#define F_CPU 16000000UL
#include <avr/io.h>
#include <util/delay.h>

void setup() {
  // Set Pin 11 (OC1A/PB5 on ATmega2560) as an OUTPUT
  pinMode(11, OUTPUT);

  // 1. Reset Timer 1 Control Registers
  TCCR1A = 0;
  TCCR1B = 0;

  // 2. Set Waveform Generation Mode: Fast PWM (Mode 14)
  // WGM13=1, WGM12=1, WGM11=1, WGM10=0
  TCCR1A |= (1 << WGM11);
  TCCR1B |= (1 << WGM13) | (1 << WGM12);

  // 3. Set Compare Output Mode for Channel A: Non-inverted PWM
  // Clears OC1A on compare match, sets at BOTTOM
  TCCR1A |= (1 << COM1A1);

  // 4. Set the TOP value in ICR1 for frequency control
  // Formula: Frequency = Clock / (Prescaler * (1 + TOP))
  // Example for ~2 kHz at 16MHz clock with a prescaler of 64:
  // 16,000,000 / (64 * 12500) = ~20 Hz
  ICR1 = 12499; 
  TCCR1B |= (1 << CS11) | (1 << CS10);

  // 5. Set the Duty Cycle using OCR1A
  // Value from 0 to ICR1. (e.g., 50% duty cycle)

for (uint16_t i = 12490; i > 0; i -= 5) {
    OCR1A = i; 
    _delay_ms(1);
  }

  // 6. Set Clock Select: Prescaler = 64
 
 
}

void loop() {
 
}