Ultrasonic

#define TRIGGER 12
#define ECHO    A12

// NodeMCU Pin D1 > TRIGGER | Pin D2 > ECHO

void setup() {

  Serial.begin (9600);
  pinMode(TRIGGER, OUTPUT);
  pinMode(ECHO, INPUT);
  pinMode(BUILTIN_LED, OUTPUT);
}

void loop() {

  long duration, distance;
  digitalWrite(TRIGGER, LOW);
  delayMicroseconds(2);

  digitalWrite(TRIGGER, HIGH);
  delayMicroseconds(10);

  digitalWrite(TRIGGER, LOW);
  duration = pulseIn(ECHO, HIGH);
  distance = (duration/2) / 29.1;

  Serial.print(distance);
  Serial.println("Centimeter:");
  delay(1000);
}