//Include servo library:
#include <Servo.h>
//Create the servo object:
Servo SM; //'SM' from Servo Motor!...
//Declare the pins to which servo and potentiometer is connected.
const int servoPin = 7;

//Define HC-SR04 & other variables!
#define echoPin 2 //attach pin D2 Arduino to pin Echo of HC-SR04
#define trigPin 3 //attach pin D3 Arduino to pin Trig of HC-SR04
long duration;     //variable for the duration of sound wave travel
int distance;      //variable for the distance measurement
int RLED1 = 7;     //Green LED...
int RLED2 = 6;     //Yellow LED...
int White_LED = 5; //Red LED...
int Buzzer = 12;

void setup(){
  pinMode(RLED1, OUTPUT);  
  pinMode(RLED2, OUTPUT);
  pinMode(White_LED, OUTPUT);
  pinMode(trigPin, OUTPUT);  //Sets the trigPin as an OUTPUT
  pinMode(echoPin, INPUT);   //Sets the echoPin as an INPUT 
  pinMode(Buzzer, OUTPUT);
  //Attach SM to pin 4 to the Arduino UNO board!
  SM.attach(4);
}

void loop(){
  //Clears the trigPin condition
  digitalWrite(trigPin, LOW);
  delay(100);
  //Sets the trigPin HIGH (ACTIVE) for 10 microseconds
  digitalWrite(trigPin, HIGH);
  delay(100);
  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; //Speed of sound wave divided by 2 (go and back)
  
  if(distance < 10){
    SM.write(90);
    digitalWrite(White_LED, LOW);
    digitalWrite(RLED1, HIGH);     
    digitalWrite(RLED2, LOW);
    delay(1000);                 
    digitalWrite(RLED1, LOW);      
    digitalWrite(RLED2, HIGH);
    delay(1000);
  }
  if(distance >= 10 && distance <= 100){
    SM.write(90);
    digitalWrite(White_LED, LOW);
    digitalWrite(RLED1, HIGH);     
    digitalWrite(RLED2, LOW);      
    tone(Buzzer, 800, 400);
    delay(1000);                 
    digitalWrite(RLED1, LOW);      
    digitalWrite(RLED2, HIGH);      
    tone(Buzzer, 800, 400);
    delay(1000);
  }
  if(distance > 100){
    SM.write(0);
    digitalWrite(RLED1, LOW);
    digitalWrite(RLED2, LOW);
    digitalWrite(White_LED, HIGH);
    delay(2000);
    digitalWrite(White_LED, LOW);
    delay(2000);
  }
}