Question about rule 2.2.8

I have a question about one new rule specific the 2.2.8, this rule say "Robots must be equipped with a switch, clearly visible to the referee, of any kind for restarting the robot when a lack of progress occurs’’
In this rule say switch if I use lego ev3 the brick only have buttons therefore it does not have a switch.
My question is that if it is possible to use said brick, since if it is used it does not comply with said rule
I believe that this is a way to improve a team and look for new alternatives.

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I think the intention of the rule is to prevent pre-mapping and hidden reparations. So if the buttons of the EV3 are clearly visible, they should be fine.
Furthermore Google shows buttons too, when you google for switch (and some extra key words to hide Nintendo switch and light switches), so maybe buttons can be considered as switches in some way.

I agree with you regarding the pre-mapping so that a button of this type can be programmed to just stop the programming and even have the mapping or you can also program it for the robot to take another action

Hi @Miduchi1

Do you think that EV3 buttons are not accepted as Switch because you can change the program with a combination of Ev3 buttons ?

Also you think that you can push only one switch (button) after LoP, so you have to make a switch on your EV3 ?

I’ld like to clearly your question.


I do not think it is a switch because in the specs of ev3 it mentions that it is a button:

Of course, it also depends on what definition you give the word switch, which is something I would like to know in order to understand well

Thank you, I inderstand.
Then TC will answer soon.


Hi Luis,

There are some reasons for implementation and clarifications for this particular rule I want to point out.

  1. As it is pointed out, the main reason for this is to resolve the pre-mapping issue once in for all. Yes, of course if there is a team that is actively trying to cheat, this is not really solution, but there are so many teams each year that accidentally skip through parts of the rule, especially with little understanding on using the same program every time of the restart.
  2. This is where we get this rule and also the 2.2.7 about the handle. So when teams do call a LOP, it is super clear to the teams and also for the referees that there is defiantly one switch that is being used and that is the only one which is being used - hopefully preventing any misunderstanding among the teams.
  3. So at the end of the day, if you have a single switch that is super obvious (the best is to have something like a toggle switch/tact switch kind of thing on the top of the robot/handle), there is no issue. It doesn’t really matter if you want to call this buttons of switches, it was more of a phrase to represent all kind of binary control method.
  4. Allowing an ev3 brick is slightly problematic to make a general statement because then this doesn’t solve the issue of having a clear binary option, but rather a cluster of switches (or buttons, whichever you wish to call). Having said that, it is also true that especially for novices, the ev3(or NXT/RCX) users will suffer from sensor port restrictions, so if you/your team is not the level to implement more sensors or add switches to your controller, then we can probably allow this, given that the EV3 screen/buttons are very clear to the judge.

Does this answer your question?


2019-20 TC

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Hi all,
especially Kai,

I’m glad this post is here, because specifically the question of what this means for teams using Lego Mindstorms is something we have discussed in regards to adopting the 2020 rules for the Austrian Open

For one I really appreciate the introduction of a handle and switch to all disciplines!
And especially on LEGO Mindstorms it can in fact be sometimes hard for a referee to judge if someone is just hastily fumbling with the buttons, because they are stressed, or trying to cheat and switch programs.

One the other hand I’m skeptical about what this means for the usually younger and less experienced teams that are using the mindstorms platform.
In general they’ll need to spend more effort than probably reasonable to not give up a sensor port just to add a switch.

Given that the rules are already a step harder with the additions like potentially continuing the maze after the evacuation zone, I personally would prefer allowing the mindstorms platform buttons, maybe with an express rule about placing the brick in a way so that they are easily visible.

Generally for the sake of our referees it would be great to have the decision clearly stated in the final rules.
Regardless of what decision is made in regards to (dis)allowing the mindstorms buttons as an on/off switch.

Thanks in advance.
Best Regards,

Referee & Referee Instructor - RCJ Austrian Open

Dear Nico,

I agree with the points you address. As I’ve slightly touched upon in my previous post, it is extra effort (and also difficult technically to an extent) to add additional sensor inputs even if it’s a switch on Mindstomrs products.

For example, if a team is beginning to learn how to do robotics through Lego Mindstorms, then in general we will allow teams to use the buttons on the intelligent brick, given that it is clearly visible on the robot (and not hiding under some contraption. However, we will not allow teams that make this case whilst having for example an Arduino that communicates with the intelligent brick.

I cannot give you when exactly the final rules will be published as it is out of the TC’s hands, but hopefully will include a comment on this. Even not, judges can refer to this thread as a rule clarification by a TC.

Also, if teams are unsure if what they have done is “acceptable” they can always message us or post on the forum for an evaluation by the TC.


2019-20 TC

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Dear Kai,

fully agree with your distinction of when the buttons may be fine, vs when a team has demonstrated that they should be capable of adding a dedicated switch.

Perfect, thanks!

Best Regards,

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So if I used an Arduino that communicates with a ev3, I need to use a switch? And if a team used two ev3 they need to used a switch?
And as it is determined that it is a team that is just learning?

Not Kai, but in the end it will always come down to the judgement of the people running the specific event.

In this case - assuming there will be some general description of when an additional switch will be required based on a teams knowledge/skill/experience - in my opinion it comes down to the general guidelines and specific judgement at the technical review stage.

If a team is capable of using and wiring an Arduino, yes by my judgement, they’ve demonstrated that they’re capable of also adding a dedicated off-switch. If they can’t, then I might have some more problems with their explanations of how they integrated the two systems on their own :wink:

If a team somehow uses two Lego bricks… Hm, there it actually gets quite tricky in my opinion.
Might depend on what exactly they do with the two, if/how they communicate and what each brick does.
Generally a setup of two bricks certainly leaves the realm of easily and clearly visibly switching the whole thing on and off.

TBH I’ve been judging RCJ for some years now and haven’t really seen several bricks used in the same robot outside of On-Stage and one Maze team that knew quite a lot and by their own admittance would have been better off with using something like an arduino, but went with what they were used to.

Do you specifically know a team that uses/wants to use more than one Lego brick @S123 ?


Yes, I know teams that use more than two bricks in Mexico most of them do and the truth is not something difficult and is something that lego allows you, two years ago I did,all the necessary information to do it:
In fact, it is not difficult to combine an arduino with a layman, since I am currently working on it here I leave the link with all the necessary information to do it: https: //

Dear Luis,

For the case of using an Arduino, I would say definitely have a switch. It is doable with a microswitch connected to ground and to a pin which is pulled high either externally or internally on the Arduino. I feel like if teams are implementing other sensors, they should be able to add an additional microswitch. So yes, in that case you will have to implement a switch that is clear to the judges.

For the EV3 situation, once again this is a case by case thing. If a team is learning, it makes no sense to add this rule because it prohibits progress. But for example, if the team has been going on for a few years and are using the lego Mindstorms kit (which is fair enough), I think such a team should consider implementing a switch. You also do point it out that it is not that difficult which is great (perhaps we can move towards sharing further information and understanding setting up the communication between EV3/NXT and a micro controller)!

I hope this answers your question.


Kai Junge
2019-20 TC

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Rescue line
I have a question about if is obligatory to put a checkpoint on the title number 23 or 24?

We alredy answer this question here.