built in led in nodemcu 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)
}