1. //初始化硬件相关配置
    2. void setup() 
    3. {
    4.   //设置板子D2为输出模型，可以输出电压
    5.   pinMode(D2, OUTPUT);
    6. }
    8. //
    9. void loop() 
    10. {
    11.   digitalWrite(D2, HIGH);   // Turn the LED on (HIGH is the voltage level)
    12.   delay(1000);              // Wait for a second
    13.   digitalWrite(D2, LOW);    // Turn the LED off by making the voltage LOW
    14.   delay(1000);              // Wait for a second
    15. }