#define MY_PIN 2
#define ME_PIN 5

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  pinMode(LED_BUILTIN, OUTPUT);
  pinMode(ME_PIN , OUTPUT);
  pinMode(MY_PIN , INPUT);

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

void loop() {
  // put your main code here, to run repeatedly:
  float distance =readDistanceCM();
  bool isNearby=distance<100;
  digitalWrite(LED_BUILTIN,isNearby);
  Serial.print("measured distance: ");
Serial.println(readDistanceCM());
delay(1000);

}