#define TRIGGER_PIN 2 
#define ECHO_PIN    4  

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

void loop() {
  
  digitalWrite(TRIGGER_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIGGER_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIGGER_PIN, LOW);

  
  long duration = pulseIn(ECHO_PIN, HIGH);

  
  int distance = duration * 0.034 / 2;

  
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" m");
  delay(1000);
}