void setup() {
  pinMode(1, INPUT_PULLUP); // set push button pin as input
  pinMode(0, OUTPUT);      // set LED pin as output
  digitalWrite(0, LOW);    // switch off LED pin

  Serial.begin(9600);       // initialize UART with baud rate of 9600 bps
}

void loop() {
 
  if (digitalRead(1) == HIGH) {
    Serial.write('0');    // send the char '0' to serial if button is not pressed.
    // digitalWrite(0, HIGH); // switch LED On
  }

  else {
    Serial.write('1');                           // send the char '1' to serial if button is pressed.
    // digitalWrite(0, LOW);  // switch LED Off
  }

}