Fading Light Switch

// Fade an LED in and out when button pressed
// Copyright 2010 by progmanos
// Code license: GPL v.3 or later
#define LED 9 // the pin for the LED
#define BUTTON 7 // the input pin where the
                 // pushbutton is connected
int i = 0;    // We'll use this to count up and down
int val = 0;  // val will be used to store the state
              // of the input pin
int old_val = 0;  // this variable stores the previous
                  // value "val"
int state = 0;  // 0 = LED off and 1 = LED on

void setup() {
  pinMode(LED, OUTPUT);  // tell Arduino LED is an output
  pinMode(BUTTON, INPUT); // and BUTTON is an input
}

void loop() {
  val = digitalRead(BUTTON);  // read input value and store it

  // check if there was a transition
  if ((val == HIGH) && (old_val == LOW)) {
    state = 1 - state;
    delay(10);
    for (i=0; i < 255; i++) { // loop from 0 to 254 (fade in)
      analogWrite(LED, i); // set the LED brightness
      delay(10);  // Wait 10ms because analogWrite
                  // is instantaneous and we would
                  // not see any change
    }
    delay(10);
  }
  else if ((val == HIGH) && (old_val == HIGH)) {
    delay(10);
    for (i = 253; i >= 0; i--) { // loop from 255 to 1 (fade out)
      analogWrite(LED, i); // set the LED brightness
      delay(10);           // Wait 10ms
    }
  }
  else if (state == 0) {
    digitalWrite(LED, LOW);
  }

  old_val = val;  // val is now old, let's store it

}