The GDC ruling states that
Per R13-c and R6-b, no, this would not be legal.
The text of R6-b is as follows
Electronics from the VEX Cortex control system are not permitted. This includes the VEXnet
Joystick, VEXnet Partner Joystick, VEX ARM® Cortex-based Microcontroller, VEXnet Key 1.0 and
2.0, 2-Wire Motor 393, and any other electronic components which are not compatible with the VEX
The MC29 is a “cortex” part, but it is notably NOT listed in R6-b, nor does it meet the criteria for items disallowed that are not in the list (“other electronic components which are not compatible with the VEX
V5 system”). The MC29 is fully compatible with the V5 Brain, as advertised by VEX.
3-Wire ports can also serve as a PWM motor port for driving the older servos and Motor Controller 29’s.
R6-b only makes cortex electronics that are not compatible with the V5 brain illegal, therefore R6-b is not relevant when discussing MC29s.
The second portion of the ruling was in regards to R13-c. R13-c states that
VEX electronics may not be used as non-functional decorations
I have a few rebuttals to this one. First off, the MC29’s in question are heavily modified, which has previously meant that the electronic device no longer meets the definition of “VEX electronics”.
The second rebuttal to this point is as follows. By this logic, a non-VEX brand, otherwise identical electronic component modified and used in the exact same way would be legal, but since the MC29 has the VEX logo on it, it is illegal. This logical conclusion is, as it turns out, quite illogical, and I would therefore be inclined to invoke G3. For those that do not recall G3, it reads:
Use common sense. When reading and applying the various rules in this document, please
remember that common sense always applies in the VEX Robotics Competition.
Disallowing a component simply because of the VEX branding betrays all common sense. This nonsensical conclusion could therefore be ameliorated with the understanding that yes, in fact, modified MC29s are legal for decorative use.
The final rebuttal that I have to the GDC’s application of R13-c is one of definition. The rule very specifically applies to
non-functional decorations. Per the text of R13, a non-functional decoration is something that
[does] not affect Robot performance in any significant way or affect the outcome of the Match
Consider the following: a Team with a robot that manipulates a ring using internal mechanisms to accomplish an arbitrary goal. The mechanisms in question obscure the state of the mechanism from the view of Drive Team Members, however the robot has sensors onboard that can determine the state of the ring mechanism. There are LED strips under the robot that are, by some method, controllable from the V5 Brain. The Team has programmed the LED lights to illuminate a certain color depending on the state of the ring mechanism. This visual feedback allows the Drive Team to more efficiently maneuver the robot, allowing them to win games that would have otherwise been lost.
A few things stand out here. First of all, one would be inclined to think “Hey! That’s not a non-functional decoration! That’s against the rules!”, and they would almost be right. This 100% does violate the criteria for non-functional decoration, which if we recall requires that a decoration “not affect Robot performance in any significant way”, which this definitely does. Where our hypothetical skeptic would be mistaken is in declaring this against the rules. In all previous years, yes, this would have been very illegal. In fact, I asked a Q&A on this last year. LED light strip usage : Robot Events. However, this year there was a small corollary added onto R13 which states that
Decorations which provide visual feedback to Drive Team Members (e.g. decorative lighting) are
permitted, provided that they do not violate any other rules and serve no other function (e.g. structural support).
R13-g very clearly allows for the lighting setup described in the above example, yet said example by no means meets the criteria for “non-functional decoration”. I would call such an apparatus “functional decoration”, or simply, “decoration” (as the corollary does).
R13-c again, if we recall, prohibits the use of VEX electronics for “non-functional decorations”. LED lights, as we’ve established, are not non-functional, therefore R13-c is completely irrelevant when considering them.
Q&A 942, which supposedly prohibits the use of MC29s for decorative lighting purposes, does so by invoking two rules which are both unquestionably inapposite for the question at hand. And, since a post on this forum is never complete without a GIF, I will conclude my argument in the only way that feels right.