Arduino. Fading an LED in and out to produce a glow effect via the PWM pins.

glow.ino

/* Fading an LED in and out to produce a glow effect 
   via the PWM pins.
*/

int timer = 10;
int pin = 3;
int val = 0;

void setup(){
  pinMode(pin, OUTPUT);
}

void loop(){
  while (val <= 220) {
    analogWrite(pin, val);
    val++;
    delay(timer);
  }
  while (val >= 30) {
    analogWrite(pin, val);
    val--;
    delay(timer);
  }
}