void setup()
{   
  pinMode(1, OUTPUT);  
   
}
void loop() { 
  for(int i=0; i<=255; i+=5) { 
    analogWrite(1,i);
    delay(30);
    digitalWrite(0,0);
    }
    for(int i=255; i>=0; i-=5) { 
    analogWrite(1,i);
    delay(30);
    digitalWrite(0,0);
    }
  }