Arduino Playground

Arduino Blink

The "Hello World" Arduino code example: Blinking an LED.

The red LED is attached to digital pin 13, represented by LED_BUILTIN in the code.

Click on "Run Code" to see it in action.

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sketch.ino

// 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);
}

// 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
  digitalWrite(LED_BUILTIN, LOW);    // turn the LED off by making the voltage LOW
  delay(1000);                       // wait for a second
}