void setup() {
  // put your setup code here, to run once:
  pinMode(13, OUTPUT); //设置13引脚为输出模式
}

void loop() {
  // put your main code here, to run repeatedly:
  digitalWrite(13, HIGH); //设置13引脚为高电平
  delay(1000); //延时1秒

  digitalWrite(13, LOW); //设置13引脚为低电平
  delay(1000); //延时1秒
}