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

int main(void) {
	DDRB |= 1 << PINB1; // Set pin 9 on arduino to output

	/* 1. Set Fast PWM mode 14: set WGM11, WGM12, WGM13 to 1 */
	/* 3. Set pre-scaler of 8 */
	/* 4. Set Fast PWM non-inverting mode */
	TCCR1A |= (1 << WGM11) | (1 << COM1A1);
	TCCR1B |= (1 << WGM12) | (1 << WGM13) | (1 << CS11);

	/* 2. Set ICR1 register: PWM period */
	ICR1 = 39999;

	/* Offset for correction */
	int offset = 800;

	/* 5. Set duty cycle */
	while(1) {
		OCR1A = 3999 + offset;
		_delay_ms(5000);
		OCR1A = 1999 - offset;
		_delay_ms(5000);
	}

	return 0;
}