char buff[3];
char recv = 0;

void setup()    {
    Serial.begin(115200);
}

void  loop()    {
  if(Serial.available() > 0)  {
    buff[recv] = Serial.read();
    recv++;  
  }  
  if(recv == 3) {
    analogWrite(PINO_R, buff[0]);
    analogWrite(PINO_G, buff[1]);
    analogWrite(PINO_B, buff[2]);
    recv = 0 ;
  }
}