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

void loop() {
  // put your main code here, to run repeatedly:
  // 设置 13 号引脚 数字量输出 高电平 => led 亮
  digitalWrite(13, HIGH);
  delay(1000);      // 等待/延迟 1s = 1000ms

  digitalWrite(13, LOW);
  delay(1000);
}