Simple Arduino Button Logger

// digital pin 2 has a pushbutton attached to it. Give it a name:
int pushButton = 2;

// the setup routine runs once when you press reset:
void setup() {
  // initialize serial communication at 9600 bits per second:
  Serial.begin(9600);
  // make the pushbutton's pin an input:
  pinMode(pushButton, INPUT);
}

int lastButtonState = 0;
unsigned long lastTime = millis();
unsigned long startTime = lastTime;

// the loop routine runs over and over again forever:
void loop() {
  // read the input pin:
  int buttonState = digitalRead(pushButton);
  unsigned long time = millis();
  unsigned long diff = time - lastTime;
  if (buttonState != lastButtonState && diff > 200) {
    // print out the state of the button:
    if (buttonState == 1) {
      Serial.println((time - startTime) / 1000.0);
    }
    lastButtonState = buttonState;
    delay(50);        // delay in between reads for stability
  }
}