RGBSerialControl.ino

const int RED_PIN   = 9;
const int GREEN_PIN  = 10;
const int BLUE_PIN   = 11;

int red = 0;
int green = 0;
int blue = 0;

void setup() {
  Serial.begin(9600);

  pinMode(RED_PIN, OUTPUT); 
  pinMode(GREEN_PIN, OUTPUT); 
  pinMode(BLUE_PIN, OUTPUT); 
}

void loop() {
  if (Serial.available() > 1) {
    switch (Serial.read()) {
      case 'r':
        if (Serial.read() == '#') {
          Serial.print(red);
          Serial.print(" ");
          Serial.print(green);
          Serial.print(" ");
          Serial.println(blue);
        }
        break;
      case 'w':
        while (Serial.available() > 0) {
          int newRed = Serial.parseInt();
          int newGreen = Serial.parseInt();
          int newBlue = Serial.parseInt();

          if (Serial.read() == '#') {
            red = constrain(newRed, 0, 255);
            green = constrain(newGreen, 0, 255);
            blue = constrain(newBlue, 0, 255);

            analogWrite(RED_PIN, red);
            analogWrite(GREEN_PIN, green);
            analogWrite(BLUE_PIN, blue);
            
            Serial.println("OK");
          }
        }
        break;
      default:
        break;
    }
  }
}