void setup(){
  Serial.begin(9600); //开始串口通信
  pinMode(2, INPUT_PULLUP);
  pinMode(13, OUTPUT);
}

void loop(){
  int sensorval=digitalRead(2); //将开关状态数值读取到变量中
  Serial.println(sensorval); //输出开关状态数值

  if(sensorval=HIGH){
    digitalWrite(13, LOW);
  } else {
    digitalWrite(13, HIGH);
  }
}