Example-1
// Choose the board type as NodeMCU 1.0 (ESP12-3 Module)
void setup()
{
// initialize digital pin 5 as an output. (Called D2 on the SOC)
pinMode(5, OUTPUT);
}
// the loop function runs over and over again forever
void loop() {
digitalWrite(5, HIGH); // turn the LED on (HIGH is the voltage level)
delay(1000); // wait for a second
digitalWrite(5, LOW); // turn the LED off by making the voltage LOW
delay(1000); // wait for a second
}