int Led1 = 13;
int Led2 = 12;

const int trigPin = 11;
const int echoPin = 10;
long duration = 0;
int distance = 0;


void setup() {
  pinMode(Led1, OUTPUT);
  pinMode(Led2, OUTPUT);

  pinMode(trigPin, OUTPUT); // Sets the trigPin as an Output
pinMode(echoPin, INPUT); // Sets the echoPin as an Input

  Serial.begin(9600);
}

void loop() {
  
  if(Serial.available())
  {
    char data = Serial.read();
//    Serial.println(data);
    if(data == 'R'){LedOn1();}
    if(data == 'G'){LedOn2();}
    if(data == 'S'){LedStop();}
    
  }

  // 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;
  // Prints the distance on the Serial Monitor
//  Serial.print(" ");
  Serial.println(distance);
  delay(50);
}

void LedOn2()
{
  digitalWrite(Led2, HIGH);
}

void LedOn1()
{
  digitalWrite(Led1, HIGH);
}

void LedStop()
{
  digitalWrite(Led1, LOW);
  digitalWrite(Led2, LOW);
}