#define trig_pin 5
#define echo_pin 18
#define led_pin 13
void setup() {
  Serial.begin(9600);
  pinMode(trig_pin, OUTPUT);
  pinMode(echo_pin, INPUT);
  pinMode(led_pin, OUTPUT);
  digitalWrite(led_pin, HIGH);
}
void loop() {
  long duration;
  float distance;
  digitalWrite(trig_pin, LOW);
  delayMicroseconds(2);
  digitalWrite(trig_pin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trig_pin, LOW);
  duration = pulseIn(echo_pin, HIGH);
  distance = duration * 0.034 / 2;
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");
  if (distance > 0 && distance < 10) {
    digitalWrite(led_pin, HIGH);
  } else {
    digitalWrite(led_pin, LOW);
  }

  delay(1000);
}