#define F_CPU 8000000UL
#include <avr/io.h>
void T1_PWM(uint16_t dutyCycle);
int main(void) {
	DDRB |= (1<<PB5);
	uint8_t duty=90; 				// duty cycle in percent
	T1_PWM(duty);
}
void T1_PWM(uint16_t dutyCycle)
{
	uint16_t TOP = 31249;			// This corresponds to 31250 Hz
	TCCR1A |= (1 << COM1A1) | (1 << COM1A0) | (1 << WGM11);
	TCCR1B |= (1<<WGM13) |  (1<<WGM12) | (1 << CS12);
	OCR1A = (dutyCycle/100.0)*TOP;		// The ON time is stored in OCR1A
	ICR1 = TOP;					// Set the period to 1 second.
}