#define TRIG_PIN 9
#define ECHO_PIN 10
float filtArray [20];
float distance;

void setup() {
  Serial.begin(9600);
  pinMode(TRIG_PIN, OUTPUT);
pinMode(ECHO_PIN, INPUT);
}

void loop(){
  Serial.println("รอก่อนกำลังตรวจสอบ...");
  for(int sample = 0; sample < 20; sample++){
     filtArray[sample] = ultrasonicMeasure();
delay(50);
  }

  for (int i = 0; i < 19; i++){
    for (int j = i + 1; j < 20; j++){
      if (filtArray[i] > filtArray[j]){
        float swap = filtArray[i];
        filtArray[i] = filtArray[j];
        filtArray[j] = swap;
      }
    }
  }
  double sum = 0;
  for (int sample = 5; sample < 15; sample++){
    sum += filtArray[sample];
  }
  distance = sum / 10;
  Serial.print("ระยะที่ตรวจจับวัตถุได้เฉลี่ย : ");
  Serial.print(distance);
Serial.print(" เซนติเมตร");
}
float ultrasonicMeasure(){
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  float duration_us = pulseIn(ECHO_PIN, HIGH);
  float distance_cm = 0.017 * duration_us;
  return distance_cm;
}