//example PWM sketch
//globals
int ledPin = 9;

void setup(){
  pinMode(ledPin, OUTPUT);
  digitalWrite(ledPin, LOW);
}//end of setup

void loop(){
  //increasing the LED brightness
  for(int bright=0; bright<=255; bright=(bright+5)){
    analogWrite(ledPin, bright);
    delay(20);
    }//end of increasing bightness
    
  //decreasing the LED brightness
  for(int dim=255; dim>=0; dim=(dim-5)){
    analogWrite(ledPin, dim);
    delay(20);
    }//end of decreasing brightness
}//end of loop