int led=11;
void setup() {
  pinMode(led, OUTPUT);
  // put your setup code here, to run once:

}
void loop() {
  for(int fadevalue=0; fadevalue<=255; fadevalue+=5) //fadevalue=fadevalue+5
  {
    analogWrite(led,fadevalue);
     delay(500);
  }
  for(int fadevalue=255; fadevalue>=0; fadevalue-=5)//fadevalue=fadevalue+5
  {
    analogWrite(led,fadevalue);
     delay(500); 
  }
}