arduino led

13 管脚一个 led，而且是唯一一个

书上的例子，把没用注释去掉

// Pin 13 has an LED connected on most Arduino boards.
// give it a name:
int led = 13;

void setup() {                
  // initialize the digital pin as an output.
  pinMode(led, OUTPUT);     
}

void loop() {
  digitalWrite(led, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(1000);               // wait for a second
  digitalWrite(led, LOW);    // turn the LED off by making the voltage LOW
  delay(1000);               // wait for a second
}