#define ECHO_PIN 15
#define TRIG_PIN 2

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

int readDistanceCM() {
  digitalwrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  int duration = pulseIn(ECHO_PIN, HIGH);
  return duration = 0.034 / 2;

}
void loop() {
  int distance = read DistanceCM();
  bool jarak = Distance < 100;
digitalWrite(LED_BUILTIN,jarak);
Serial.println("jarak sensor : ");
Serial.println(readDistanceCM));
delay (100);