Communication between several Lego Bricks within a single robot


Is the use of several Lego Bricks* within a single robot allowed, and which modes of communication between bricks are legitimate?
*(generalizing NXT, EV3, SPIKE as “brick” for this)

  1. Wired connections
    Some bricks can be daisy-chained with a wired connection - according to some past forum posts this is OK, and nothing else than using different circuit boards in one robot. I have also applied this interpretation for one team in this year’s Austrian Open already.
    Is this interpretation still correct?

  2. Wireless connections
    The general rules state that:

Robots are not allowed to use any kind of communication during game play unless the communication between two robots is via Bluetooth class 2 or class 3 (range shorter than 20 meters) or via ZigBee.

I’ve found conflicting interpretations in past forum posts, asserting either that this means communication within a single robot is just not allowed at all, or that it is fine if following the rule.

Personally, I can also see this rule just not applying at all for a single robot with 1 to N Lego bricks (or RaspberryPis, Arduinos, …) just being components within the same robot and there being no current restrictions on how components within one robot communicate.

I was asked this question by a team who qualified for the European and World Cup events at the Austrian Open, and would appreciate it if we could give a general answer to this.
(Possibly even adding some clarifying wording to future 2024 rules)

Thanks in advance!
RobocupJunior Austria

Hi @Nico ,

Thank you for your question, this definitely started a conversation in the committee to see how we can improve the rules for 2024 :slight_smile:

Is the use of several Lego Bricks within a single robot allowed?*
Yes, having more than one “brain” it’s allowed. This can be a combination of bricks (like 2 LEGO bricks), with multiple brands or types (1 brick with 1 arduino).

which modes of communication between bricks are legitimate?
1. Wired connections
You’re correct, all wired connections within a robot are allowed. All the wires required to connect the “brains” are considered part of the robot.

2. Wireless connections
The intention of that rule was to simplify other competitions where they require multiple robots, like RCJ Soccer and RCJ OnStage. In the scenario of RCJ Rescue, it is there to provide a valid wireless way of communication with other teams during the super team competitions.

Now, considering the ambiguity of the rules and after discussing this with the committee members, we determined that for now we will be accepting wireless communication between the same robot components with the previously mentioned protocols. We recommend teams to do not opt for this option as we cannot guarantee that the wireless communications will work great in the competition arena and/or there will be a “safe” connection guarantee for these protocols (for example, a malicious spectator trying to connect to unsafe bluetooth ports to cause performance issues in the robot). We will be working into making better changes in the 2024 rules for this case.

Thank you!

Diego Garza Rodriguez
2023 Committee

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