int RED = 9;
int GREEN = 10;
int BLUE = 11;

void setup() {
  pinMode(RED, OUTPUT);
  pinMode(GREEN, OUTPUT);
  pinMode(BLUE, OUTPUT);

  Serial.begin(9600);
}

void loop() {

  if (Serial.available()) {

    char val =  Serial.read();

    Serial.println(val);

    if (val == 'r') {
      digitalWrite(RED, HIGH);
      Serial.println("red");
    }

    if (val == 'b') {
      digitalWrite(BLUE, HIGH );
      Serial.println("blue");
    }

    if (val == 'g') {
      digitalWrite(GREEN, HIGH);
      Serial.println("green");
    }

    if (val == 'a') {
      digitalWrite(RED, HIGH);
      digitalWrite(BLUE, HIGH );
      digitalWrite(GREEN, HIGH);
    }

    if (val == 'o') {
      digitalWrite(RED, LOW);
      digitalWrite(BLUE, LOW );
      digitalWrite(GREEN, LOW);
    }

  }
}