/*
  Blink
  Turns an LED on for one second, then off for one second, repeatedly.
*/

// define variables here
// variables should be defined before setup()

// You must include void setup() and void loop() in every Arduino sketch, or the program won't compile!

// the setup function runs once when you press reset or power the board
// setup()函数只运行一次，用来启动Arduino控制器，将运行中不改变的数值和属性固化到芯片中
void setup() {
  // initialize digital pin LED_BUILTIN as an output.
  
  // pinMode(pin,mode):将指定的引脚配置为输入或输出
  //     - pin:所需要设置的引脚号
  //     - mode:INPUT/OUTPUT（pinMode也可以是INPUT_PULLUP，使用引脚内置的上拉电阻）
  pinMode(LED_BUILTIN, OUTPUT);
}

// loop()函数循环执行，直到按下reset键或者移除电源
void loop() {

  // digitalWrite(pin,HIGH/LOW):数字引脚输出，HIGH表示高电平（5v）,LOW表示低电平（0v）
  // delay(num):暂停执行程序num毫秒  
  digitalWrite(LED_BUILTIN, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(1000);                       // wait for a second
  digitalWrite(LED_BUILTIN, LOW);    // turn the LED off by making the voltage LOW
  delay(1000);                       // wait for a second
}

// define variables before setup()

void setup(){
    //将运行中不变的数值和属性固化到芯片中
}

void loop(){
   //需要循环执行的代码  
}

pinMode(LED_BUILTIN, OUTPUT);

digitalWrite(LED_BUILTIN, HIGH);

delay(1000);