#define TRIG D1
#define ECHO D2

void setup() {
  pinMode(TRIG, OUTPUT);
  pinMode(ECHO, INPUT);
  Serial.begin(9600);
}

void loop() {
  digitalWrite(TRIG, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG, LOW);

  long duration = pulseIn(ECHO, HIGH);

  int distance = (duration * 0.034 / 2);

  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");

  delay(200);
}