void setup() {
  pinMode(9, OUTPUT);
TCCR1B = (TCCR1B & 0xF8) | 1;
Serial.begin(9600);
}


void loop() {
byte duty = analogRead(A0) / 4;
analogWrite(9, duty);
Serial.print(" -> Input value: ");
Serial.print(analogRead(A0));
Serial.print(" -> Output value: ");
Serial.println(9, OUTPUT);
}