int ledPin = 0;
int brightness = 0;
int fadeAmount = 5;
void setup() {
  // put your setup code here, to run once:
  pinMode(ledPin, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
    analogWrite(ledPin,brightness);
    brightness+=fadeAmount;
  if(brightness==0 || brightness==255){
      fadeAmount=-fadeAmount;
    }
  delay(30);
}