Blink

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

#include "Arduino.h"

// Set LED_BUILTIN if it is not defined by Arduino framework
#define LED_BUILTIN 2

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

void loop() {
  // turn the LED on (HIGH is the voltage level)
  digitalWrite(LED_BUILTIN, HIGH);

  // wait for a second
  delay(500);

  // turn the LED off by making the voltage LOW
  digitalWrite(LED_BUILTIN, LOW);

  // wait for a second
  delay(500);
}