// ==========================================================
// Push button using the built in 20k pullup resistor
// Debounce is just a simple 1/2 second delay
// ----------------------------------------------------------
// For more information about pins, pull up resistors, etc.
// https://www.arduino.cc/en/Tutorial/Foundations/DigitalPins
// ==========================================================

// ----------------------------------------------------------
// ---- global
// ----------------------------------------------------------

const int baudrate  = 19200;
const int buttonPin = 2;
const int ledPin    = 7; 
bool      ledState  = false;

// ----------------------------------------------------------
// ---- setup
// ----------------------------------------------------------

void setup()
{
  pinMode(buttonPin,INPUT_PULLUP);
  pinMode(ledPin,OUTPUT);
  digitalWrite(ledPin,LOW);
  Serial.begin(baudrate);
}

// ----------------------------------------------------------
// ---- loop
// ----------------------------------------------------------

void loop()
{
  if(digitalRead(buttonPin) == LOW)
  {
    Serial.println("LOW");
    Serial.flush();

    if (ledState)
    {
      digitalWrite(ledPin,LOW);
      ledState = false;
    }
    else
    {
      digitalWrite(ledPin,HIGH);
      ledState = true;
    }

    delay(500);
  }
}