/***************************************************************************************/
//Arduino Proficiency 00
//Use an ultrasonic sensor to control the output of 4 LEDs based on detected range
/***************************************************************************************/
// defines pins numbers
const int trigPin = 9;
const int echoPin = 10;
const int redLed = 2;
const int blueLed = 3;
const int greenLed = 4;
const int yellowLed = 5;

// defines variables
const int buffersize = 10;
int buffer[buffersize] ;
int index;
long duration;
int distance;
int distance_in;

//function declarations
int average();

void setup() {
  pinMode(trigPin, OUTPUT); // Sets the trigPin as an Output
  pinMode(echoPin, INPUT); // Sets the echoPin as an Input
  pinMode(redLed,OUTPUT);
  pinMode(blueLed,OUTPUT);
  pinMode(greenLed,OUTPUT);
  pinMode(yellowLed,OUTPUT);
  Serial.begin(9600); // Starts the serial communication
}
void loop() {

  int sensorAvg;
  //Clear all LEDs
  digitalWrite(redLed,LOW);
  digitalWrite(blueLed,LOW);
  digitalWrite(greenLed,LOW);
  digitalWrite(yellowLed,LOW);  
  // Clears the trigPin
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  // Sets the trigPin on HIGH state for 10 micro seconds
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  // Reads the echoPin, returns the sound wave travel time in microseconds
  duration = pulseIn(echoPin, HIGH);
  // Calculating the distance
  distance = duration * 0.034 / 2;  //distance =  speed of sound * time/2 |(speed of sound =  340 m/s =.034cm/microsecond)
   //read average sensor value
  sensorAvg = average();
  // Prints the distance on the Serial Monitor
  Serial.print("Distance in cm: ");
  Serial.println(sensorAvg);
  delayMicroseconds(10);
  distance_in = sensorAvg * 0.393701; // 1cm = 0.393701 inch
    // Prints the distance on the Serial Monitor
  Serial.print("Distance in Inch: ");
  Serial.println(distance_in);
  if(distance_in>=4 && distance_in<=8)
  {
    digitalWrite(redLed,HIGH);
    Serial.print("Range is 4-8 inches\n");
    delay(1000);

  }
  else if(distance_in>=8 && distance_in<=12)
  {
    digitalWrite(blueLed,HIGH);
    Serial.print("Range is 8-12 inches\n");
    delay(1000);
  }
  else if(distance_in>=12 && distance_in<=16)
  {
    digitalWrite(greenLed,HIGH);
    Serial.print("Range is 12-16 inches\n");
    delay(1000);
  }
  else if(distance_in>=16 && distance_in<=20)
  {
    digitalWrite(yellowLed,HIGH);
    Serial.print("Range is 16-20 inches\n");
    delay(1000);
  }
  else
  {
      digitalWrite(redLed,LOW);
      digitalWrite(blueLed,LOW);
      digitalWrite(greenLed,LOW);
      digitalWrite(yellowLed,LOW); 
      delay(1000);
     Serial.print(" Not in range \n");
  }
  
  //update average buffer
  buffer[index]=distance;
  index++;
  if(index>=buffersize)
  {
	  index=0;
  }
  
}

//sensor reading averaging function
int average()
{
   long sum = 0;
   int i;
   int avg;
   
   for(i=0;i<buffersize;i++)
   {
	 sum += buffer[i]  ;
   }
   
   avg = (sum/buffersize);
   
   return avg;
}