//---  Reads the state of a switch, lights LED and sends serial data accordingly
//
//  -- Wire an LED from Digital Pin 7 thru a 330 ohm resistor to ground
//  -- Wire a switch between Digital Pin 5 and ground
//----------------------------------------------------------------------------------

int buttonState = 0;        // create variable for storing "state" of the button
int ledPin = 7;             // create variable for LED pin number
int buttonPin = 5;          // create variable for button pin number

void setup() {                       
  Serial.begin(9600);                // start serial port at 9600 bps:
  pinMode(ledPin, OUTPUT);           // initialize the digital pin as an output (for LED.)
  pinMode(buttonPin, INPUT_PULLUP);  // initialize the digital pin as an input (for switch.)

}
void loop()  {                  
  buttonState = digitalRead(buttonPin); // "Read" the voltage present on the pin (check switch.)
  
 // If the pin wired to the button is low, the switch is closed
  if (buttonState == LOW) {     
    digitalWrite(ledPin, HIGH);             // turn LED on: 
    Serial.println(0);                      // Send ASCII message to serial (USB)
  } 
   // Otherwise, assume the switch is open.
  else {
    digitalWrite(ledPin, LOW);                // turn LED off:
    Serial.println(1);                        // Send ASCII message to serial (USB)
  }
  delay(25);
}