fade LED

int led = 9;         // the PWM pin the LED is attached to

int brightness = 0;  // how bright the LED is

int fadeAmount = 5;  // how many points to fade the LED by

// the setup routine runs once when you press reset:

void setup() {

  // declare pin 9 to be an output:

  pinMode(led, OUTPUT);

}

// the loop routine runs over and over again forever:

void loop() {

  // set the brightness of pin 9:

  analogWrite(led, brightness);

  // change the brightness for next time through the loop:

  brightness = brightness + fadeAmount;

  // reverse the direction of the fading at the ends of the fade:

  if (brightness <= 0 || brightness >= 255) {

    fadeAmount = -fadeAmount;

  }

  // wait for 30 milliseconds to see the dimming effect

  delay(30);

}