PRJ - Blink

2024-05-29

From: Blink | Arduino Documentation

电路连接

13 引脚连接（驱动） LED。串接限流电阻。

为了方便，该 LED 是集成在板上的。所以此实验实际不需要外接电路。

Code

LED_BUILTIN 是什么？ 是 13 吗？ 13 是外置的，还是板上 LED?

/*
  Blink

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

  Most Arduinos have an on-board LED you can control. On the UNO, MEGA and ZERO
  it is attached to digital pin 13, on MKR1000 on pin 6. LED_BUILTIN is set to
  the correct LED pin independent of which board is used.
  If you want to know what pin the on-board LED is connected to on your Arduino
  model, check the Technical Specs of your board at:
  https://www.arduino.cc/en/Main/Products


  https://www.arduino.cc/en/Tutorial/BuiltInExamples/Blink
*/

// the setup function runs once when you press reset or power the board
void setup() {
  // initialize digital pin LED_BUILTIN as an output.
  pinMode(LED_BUILTIN, OUTPUT);

  Serial.begin(9600);
}

// the loop function runs over and over again forever
void loop() {
  digitalWrite(LED_BUILTIN, HIGH);      // turn the LED on (HIGH is the voltage level)
//  delay(1000);                        // wait for a second
  delay(200);
  digitalWrite(LED_BUILTIN, LOW);       // turn the LED off by making the voltage LOW
  //  delay(1000);                      // wait for a second
  Serial.println(LED_BUILTIN);          // 1
  delay(1000);                          // 2
}

1. 从调式串口打印 LED_BUILTIN 的值，看到 UNO 的确实是 13。

2. 改变 delay() 的时长，观看板上 LED 闪烁的频率与占空比。