void setup(){
  pinMode(5, OUTPUT);
  Serial.begin(9600);
}
void loop(){
  for(int i=0;i<=255;i++){
    analogWrite(5,i);
    Serial.println(i);
    delay(10);
  }
  for(int i=255;i>=0;i--){
    analogWrite(5,i);
    Serial.println(i);
    delay(10);
  }
}