sw + brightness + fade_amount

 int brightness = 0;

int fade_amount = 5;

int reading;

unsigned long last_debounce_time = 0;

int btn_state;

int last_btn_state ;

void setup()

{

  Serial.begin(9600);

  pinMode(2, INPUT);

  digitalWrite(10,LOW);

}

void loop()

{

 reading=digitalRead(2);

 if(reading != last_btn_state)

 {

  last_debounce_time=millis();

 }

 if((millis()-last_debounce_time)>50)

 {

  if(reading !=btn_state)

  {

    btn_state=reading;

    if(btn_state==LOW) chg_brightness();

  }

  else

  {

    if((millis()-last_debounce_time)>1000)

    {

      if(btn_state==LOW) chg_brightness();

    }

  }

 }

 last_btn_state=reading;

}

void chg_brightness()

{

  brightness = brightness + fade_amount;

  if (brightness > 255)brightness = 255;

  if (brightness < 0)brightness = 0;

  if (brightness == 255 || brightness == 0) fade_amount = -fade_amount;

  analogWrite(10, brightness);

  Serial.println(brightness);

  delay(30);

}