/*
 LightSwitchPullup
 Turn an LED on and off.
 Internal pullup version.
 */

int pushButtonPin = 2;  // connect the push button to digital pin 2
int ledPin = 13;        // connect the LED to pin 13
int buttonState;        // stores current button state 

void setup() {
  pinMode(pushButtonPin, INPUT);      // make the pushbutton's pin an input
  digitalWrite(pushButtonPin, HIGH);  // turn on internal pullup resistors
  pinMode(ledPin, OUTPUT);            // make LED's pin an output
}

void loop() {
  buttonState = digitalRead(pushButtonPin);  // read the input pin

  // set LED state accordingly
  // becasue we are using pullup resistors, the logic is inverted;
  // in other words, pressed produces LOW, un-pressed produces HIGH.
  if (buttonState == LOW)        // if the button is pushed
    digitalWrite(ledPin, HIGH);  // turn the LED on
  else                           // otherwise
    digitalWrite(ledPin, LOW);   // turn the LED off
}