#define echoPin 3 
#define trigPin 2 
#define LEDPin 13
int LED_EMPTY = 6;
int LED_FULL = 7;
int LED_PENDING = 8;
int BUZZER = 4;

void ULT(void);

int maximumRange = 200; 
int minimumRange = 0; 
long duration, distance; 

void setup() {
  Serial.begin (115200);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(LEDPin, OUTPUT); 
  pinMode(LED_EMPTY, OUTPUT);
  pinMode(LED_FULL, OUTPUT);
  pinMode(LED_PENDING, OUTPUT);
  pinMode(BUZZER, OUTPUT);
}

void loop() {
  ULT();
  Serial.println(distance);  
  if(distance >= 200){
    digitalWrite(LED_EMPTY,1);
    digitalWrite(LED_PENDING,0);
    digitalWrite(LED_FULL,0);
    delay(1000);
    Serial.println("Empty Space.");
  }
  else if(distance < 200 && distance >= 50){
    digitalWrite(LED_EMPTY,0);
    digitalWrite(LED_PENDING,1);
    digitalWrite(LED_FULL,0);
    tone(BUZZER, 800);
    delay(100);
    digitalWrite(LED_EMPTY,0);
    digitalWrite(LED_PENDING,0);
    digitalWrite(LED_FULL,0);
    noTone(BUZZER);
    delay(500);
    Serial.println("Car is going to park here or going out.");
  }
    else{
    digitalWrite(LED_EMPTY,0);
    digitalWrite(LED_PENDING,0);
    digitalWrite(LED_FULL,1);
    delay(1000);
    Serial.println("Car is Parking.");
  }
}

void ULT(){
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  duration = pulseIn(echoPin, HIGH);
  distance = duration / 58.2;
}