char data;
#define RED 16
#define GREEN 15
#define BLUE 14
void setup()
{
  Serial.begin(9600);
  pinMode(RED, OUTPUT);
  pinMode(GREEN, OUTPUT);
  pinMode(BLUE, OUTPUT);
  Serial.println("Press a key");
}
void loop()
{
  if (Serial.available())
  {
    data = Serial.read() ;
    if(data == 'R')
    { digitalWrite(RED,1);
      digitalWrite(GREEN,0);
      digitalWrite(BLUE,0);}
    if(data == 'G')
    { digitalWrite(RED,0);
      digitalWrite(GREEN,1);
      digitalWrite(BLUE,0);}
    if(data == 'B')
    { digitalWrite(RED,0);
      digitalWrite(GREEN,0);
      digitalWrite(BLUE,1);}
      if(data == 'C')
    { digitalWrite(RED,0);
      digitalWrite(GREEN,0);
      digitalWrite(BLUE,0);}
     }
     
}