RGB_LED_Controller.ino

int data;
int redPin = 9;
int greenPin = 10;
int bluePin = 11;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  pinMode(redPin, OUTPUT);
  pinMode(greenPin, OUTPUT);
  pinMode(bluePin, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:

  digitalWrite(redPin, HIGH);
  digitalWrite(greenPin, HIGH);
  digitalWrite(bluePin, HIGH);

  if (Serial.available() > 0) {
    data = Serial.read();
  }

  if (data == 'r') {
    digitalWrite(redPin, LOW);
    digitalWrite(greenPin, HIGH);
    digitalWrite(bluePin, HIGH);
  } else if (data == 'g') {
    digitalWrite(redPin, HIGH);
    digitalWrite(greenPin, LOW);
    digitalWrite(bluePin, HIGH);
  } else if (data == 'b') {
    digitalWrite(redPin, HIGH);
    digitalWrite(greenPin, HIGH);
    digitalWrite(bluePin, LOW);
  } else {
    digitalWrite(redPin, HIGH);
    digitalWrite(greenPin, HIGH);
    digitalWrite(bluePin, HIGH);
  }
}