void efeitofade(){
    int r,g,b;
    analogWrite(BLUE,255);
    for(r=0;r<=255;r++){
      analogWrite(RED,r);
      delay(5);
    }
    for(b=255;b>=0;b--){
      analogWrite(BLUE,b);
      delay(5);
    }
    for(g=0;r<=255;g++){
      analogWrite(GREEN,g);
      delay(5);
    }
    for(r=255;r>=0;r--){
      analogWrite(RED,r);
      delay(5);
    }
    for(b=0;b<=255;b++){
      analogWrite(BLUE,b);
      delay(5);
    }
    for(g=255;g>=0;g--){
      analogWrite(GREEN,g);
      delay(5);
    }
  }