debounce sw

 boolean led_state = LOW;

boolean btn_state;

void setup()

{

  pinMode(2, INPUT);

  pinMode(13, OUTPUT);

}

void loop()

{

  btn_state = digitalRead(2);

  if (btn_state == LOW)

  {

    led_state=!led_state;

    digitalWrite(13,led_state);

    delay(20);

    while(1)

    {

      if(digitalRead(2)==HIGH)break;

    }

    delay(20);

  }

}