int ledPin = 9;
int buttonPin = 2;
int potPin = A0;
int readValue;
int writeValue;

int buttonState;             // the current reading from the input pin
int lastButtonState = HIGH;   // the previous reading from the input pin

// the following variables are unsigned longs because the time, measured in
// milliseconds, will quickly become a bigger number than can be stored in an int.
unsigned long lastDebounceTime = 0;  // the last time the output pin was toggled
unsigned long debounceDelay = 50;    // the debounce time; increase if the output flickers

int ButtonPress = 0;

void setup() {
  Serial.begin(9600);
  pinMode(ledPin, OUTPUT);
  pinMode(buttonPin, INPUT_PULLUP);
  pinMode(potPin, INPUT);
}

void loop() {
  // read the state of the switch into a local variable:
  int reading = digitalRead(buttonPin);

  // check to see if you just pressed the button
  // (i.e. the input went from LOW to HIGH), and you've waited long enough
  // since the last press to ignore any noise:

  // If the switch changed, due to noise or pressing:
  if (reading != lastButtonState) {
    // reset the debouncing timer
    lastDebounceTime = millis();
  }

  if ((millis() - lastDebounceTime) > debounceDelay) {
    // whatever the reading is at, it's been there for longer than the debounce
    // delay, so take it as the actual current state:

    // if the button state has changed:
    if (reading != buttonState) {
      buttonState = reading;

      // only toggle the LED if the new button state is HIGH
      if (buttonState == LOW) {
        if (ButtonPress == 1)
          ButtonPress = 0;
        else
           ButtonPress = 1;
      }
    }
  }

  lastButtonState = reading;

  Serial.println(ButtonPress);

  if (ButtonPress == 1)
  {
    readValue = analogRead(potPin);
    writeValue = (255./1023.) * readValue;
    analogWrite(ledPin, writeValue);
  }
  else
    analogWrite(ledPin, 0);
}