#define TRIG_PIN 18
#define ECHO_PIN 5
#define LED 12
float duration_us, distance_cm;

float tenpetature ;
float humidity ;

void setup() {
  Serial.begin(115200);
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  pinMode(LED, OUTPUT);
}

void loop() {
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  duration_us = pulseIn(ECHO_PIN, HIGH);
  distance_cm = 0.017 * duration_us;

  if (distance_cm < 30) {
    digitalWrite(LED, HIGH);
  }
  else{
    digitalWrite(LED, LOW);
  }

  Serial.print("distanceA: ");
  Serial.print(distance_cm);
  Serial.println(" cm   ");

  delay(500);
}