//For Ultrasonic Sensor
#define trig_Pin 9
#define echo_Pin 10
#define buzzer 11
#define ledPin 13
#define potPin A0

//Detection Distance in CM
unsigned int detectDistance;          //For Storing the detection Distance
unsigned int baseDetection = 5;       //Base Value for the DetectDistance in case the Potentiometer does not work
unsigned int potValue;                //For Storing the mapped values for potentiometer

//For Timing: Reading Sensor every set time
unsigned long currentMillis;        //For storing arduino built-in timer
unsigned long previousMillis;       //For Storing the last/previous Millis recorded
unsigned long refreshRate = 1000;   //1000 = 1 sec; Change this if you want faster readings the lower the number the faster
                                       
void setup() {
//For Ultrasonic Sensor Pin Mode
pinMode(trig_Pin, OUTPUT);          //Trigger Pin at pin 9
pinMode(echo_Pin, INPUT);           //Echo Pin at pin 10

//For Potentiometer Pin Mode
pinMode(potPin, INPUT);             //Potentiometer center pin at pin A0

//For Output Pin Mode
pinMode(buzzer, OUTPUT);            //Buzzer at Pin 11
pinMode(ledPin, OUTPUT);            //Led at Pin 13

Serial.begin(9600); // Starts the serial communication
}
 
void loop() {
  input();    //Input code run
  output();   //Output code run
}

//for Checking Distance using Ultrasonic
float checkdistance() {
  digitalWrite(trig_Pin, LOW);
  delayMicroseconds(2);
  digitalWrite(trig_Pin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trig_Pin, LOW);

  //Reads the emitted  echo from the Trigger Pin and calculates
  //it for how long the echo travels from the reflected surface
  float distance = pulseIn(echo_Pin, HIGH) / 58.00;
  delay(10);

  //everytime the check distance will be called out
  //it will give the value of distance
  return distance;
}

//for all input program
void input()
  {
    //mapping the values for the potentiometer which will be added to the detectDistance's value
    potValue = analogRead(potPin);
    unsigned int adjustedValue = map(potValue, 0, 1023, 0, 95);
    detectDistance = baseDetection + adjustedValue;
  }

//for output program
void output()
  {
    //Time Starts now
    currentMillis = millis();

    //If refreshRate elapsed or If target time is achieved
    if (currentMillis - previousMillis >= refreshRate)
      {
        //Checks the distance and send it to the Serial Monitor
        Serial.print("Reading: ");
        Serial.println(checkdistance());
        Serial.print("Set Distance: ");
        Serial.println(detectDistance);
        
        //If read distance is less than or equals to the set detect distance
        if (checkdistance() <= detectDistance)
          {
            //For LED Output
            digitalWrite(ledPin, HIGH);   //sets the led turned on
    
            //For Buzzer Output
            digitalWrite(buzzer, HIGH);  //sets the buzzer turned on
          }

        //else the read distance is greater than the set detect distance
        else
          {
            //For LED Output
            digitalWrite(ledPin, LOW);    //sets the led turned off
    
            //For Buzzer Output
            digitalWrite(buzzer, LOW);    //sets the buzzer turned off
          }
      }
  }