const int trigPin=3;
const int echoPin=2;
int ledPinArray[] = {4,5,6,7};
unsigned long duration;
int distance_cm;
const int buzzer=8;




void setup()
{
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin,INPUT);
  
  for (int i=0;i<4;i++){
    pinMode(ledPinArray[i], OUTPUT);
  }
  
  Serial.begin(9600);
}

void loop()
{
    
  digitalWrite(trigPin, LOW);
  delayMicroseconds(5);
  
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  
  digitalWrite(trigPin, LOW);
  
  duration = pulseIn(echoPin, HIGH);
  
  distance_cm = (duration/2) / 29.1;
  
  Serial.println(distance_cm, DEC);
  
  displayLed(distance_cm);
  delay(1000);
  
}

void displayLed(int numToShow){
  
  for (int i=0;i<4;i++)
  {
   digitalWrite(ledPinArray[i], LOW); // All values initialised as low
  }
  if (numToShow <280){
    digitalWrite(ledPinArray[3], HIGH);
     digitalWrite(ledPinArray[2], LOW);
     digitalWrite(ledPinArray[1], LOW);
     digitalWrite(ledPinArray[0], LOW);
  }
  if (numToShow <250){
    digitalWrite(ledPinArray[3], LOW);
     digitalWrite(ledPinArray[2], HIGH);
     digitalWrite(ledPinArray[1], LOW);
     digitalWrite(ledPinArray[0], LOW);
  }
  if (numToShow <100){
     digitalWrite(ledPinArray[3], LOW);
     digitalWrite(ledPinArray[2], LOW);
     digitalWrite(ledPinArray[1], HIGH);
     digitalWrite(ledPinArray[0], LOW);
    tone(buzzer,1000,500);
  }
  if (numToShow <50){
    digitalWrite(ledPinArray[3], LOW);
     digitalWrite(ledPinArray[2], LOW);
     digitalWrite(ledPinArray[1], LOW);
     digitalWrite(ledPinArray[0], HIGH);
    tone(buzzer,1000,500);
  }
// NAMA  : Mahdalena Hasibuan
// KELAS : Mikrokontroler
// UNIV  : Universitas Islam Kuantan Singingi
// NIM   : 200210035
  if (numToShow <30){
    digitalWrite(ledPinArray[3], LOW);
     digitalWrite(ledPinArray[2], LOW);
     digitalWrite(ledPinArray[1], LOW);
     digitalWrite(ledPinArray[0], HIGH);
    tone(buzzer,1000,500);
  }
  
}