#define PIN_TRIG 18
#define PIN_ECHO 5
const int led = 2;


void setup() {
  Serial.begin(115200);
  pinMode(led, OUTPUT);
  pinMode(PIN_TRIG, OUTPUT);
  pinMode(PIN_ECHO, INPUT);
}

float readDistanceCM() {
  digitalWrite(PIN_TRIG, LOW);
  delayMicroseconds(2);
  digitalWrite(PIN_TRIG, HIGH);
  delayMicroseconds(10);
  digitalWrite(PIN_TRIG, LOW);
  int duration = pulseIn(PIN_ECHO, HIGH);
  return duration * 0.034 / 2;
}

void loop() {
  float distance = readDistanceCM();
  bool isNearby = (distance < 100);
  digitalWrite(led, isNearby);

  Serial.print("Meastred distance: ");
  Serial.println(readDistanceCM());

  delay(100);
}