esp8266 LED_BUILTIN code example

Example: esp8266 builtin led

void setup() {
  pinMode(LED_BUILTIN, OUTPUT);     // Initialize the BUILTIN_LED pin as an output
 
}

// the loop function runs over and over again forever
void loop() {
  digitalWrite(LED_BUILTIN, LOW);   // Turn the LED on (Note that LOW is the voltage level
                                    // but actually the LED is on; this is because 
                                    // it is acive low on the ESP-01)
  
  delay(100);                      // Wait for a second
  digitalWrite(LED_BUILTIN, HIGH);  // Turn the LED off by making the voltage HIGH
  
  delay(100);                      // Wait for two seconds (to demonstrate the active low LED)
}