#define PWM_PIN     (PB5)          // Use the OCR1A pin
#define PRESCALER   (64)           // Define prescaler value as 64
#define FREQ_HZ     (1000UL)       // Define the frequency as 1000 Hz
#define TOP_VALUE   (F_CPU/(FREQ_HZ * PRESCALER))

void initTimer1() {
    TCCR1A = TCCR1B = 0;
    TCNT1 = 0x000;
    // Set TOP value for the PWM period
    ICR1 = (uint16_t)(TOP_VALUE - 1);
    // Set OCR1A value for 25% duty cycle
    OCR1A = (uint16_t)(TOP_VALUE / 4);
    // Configure Timer1 in Fast PWM mode (mode 14) with prescaler of 64
    // Set non-inverted output on OC1A
    // Use Fast PWM mode and set prescaler to 64
    TCCR1A |= (1 << COM1A1) | (1 << WGM11);
    TCCR1B |= (1 << WGM13) | (1 << WGM12) | (1 << CS11) | (1 << CS10);
}

void setup() {
    DDRB |= (1 << PWM_PIN);
    initTimer1(); // Initialize Timer1
}

void loop() {
}