msp430 usando el botón como interruptor

Estoy intentando hacer esto ( enlace ) sin usar ninguna parte externa porque pude usar el botón ejemplo del mismo sitio con este código: enlace ) con mi msp430g2553 usando Energia pero no funciona, ¿alguna ayuda?

const int buttonPin = PUSH2;     // the number of the pushbutton pin
const int ledPin =  GREEN_LED;   // the number of the LED pin

int state = HIGH;      // the current state of the output pin
int reading;           // the current reading from the input pin
int previous = LOW;    // the previous reading from the input pin

// the follow variables are long's because the time, measured in miliseconds,
// will quickly become a bigger number than can be stored in an int.
long time = 0;         // the last time the output pin was toggled
long debounce = 200;   // the debounce time, increase if the output flickers

void setup(){
pinMode(buttonPin, INPUT);
pinMode(ledPin, OUTPUT);}

void loop(){
reading = digitalRead(ledPin);

// if the input just went from LOW and HIGH and we've waited long enough
// to ignore any noise on the circuit, toggle the output pin and remember
// the time
if (reading == HIGH && previous == LOW && millis() - time > debounce) {
if (state == HIGH){
  state = LOW;
}
else
  state = HIGH;
  time = millis();    }

digitalWrite(ledPin, state);
previous = reading;}