Can robot brain get/send custom messages to PC?

I am also interested to know these things.

What a great forum - thanks! Now I see why tech support steered me to here.

I don’t have a specific application in mind. (Sorry.) I just want to pick a platform that will support later needs. I’m buying a kit to get my kids (11 and 14 yo) started, but I’m a software engineer and I’d like to have the option of adding extra capabilities to an untethered robot - say, voice command as an example - that would presumably be easier for me to program on some sort of PC/Pi. Ease is key. I do have a dusty raspberry pi 3 on hand but I’m primarily a Windows developer.

I was initially thinking my only options were IQ vs. V5 - because it appeared cortex has been eclipsed by V5 in VEX marketing - but I see no one even mentioned IQ here. (I am completely new to VEX.) It seems like I should get the V5 kit and either plan to mount a Pi or figure out how to get BLE working on my laptop.


If you want to use the smart ports to communicate with the raspberry pi I co-wrote a document with in depth explanation. This will convert the RS-485 of the smart ports to UART.


This is one of the few places you can find a robotics PhD student (Tabor), a Google SWE (me) and one of the key developers of the product (James) who all reply in minutes to an ask. Probably a dozen people with masters around here too I’m forgetting about.

I feel like your kids will be best suited with a V5 if and only if they intend to do modern VRC (that is competing), a Cortex if it’s for funzies, I would avoid the older v5 (it’s not sold anymore) and Arduino/RPi stuff if robotics is not the aim but you want cheap absolute control.

Alternatively look at the IQ line and what FIRST and LEGO NTX has to offer and make the call. The NXT kind of sucks but I think they replaced it with something else which may or may not suck less or more.

I have a used Cortex and controller I can sell for cheap if that’s something you’re interested in.


No, a PIC is best for funzies.

There’s only one V5 system? Huh?

Technically, the EV3 sucks less than the NXT, but not by very much.

:eyes: how cheap?

You just don’t like me and want to prove a point. Prepare to be embarrassed…

Screen Shot 2020-06-23 at 2.10.53 PM

The PIC was also known as the v5 back in the day. So you lose your second point at a minimum.

Yes I know, it is newer but worse, or at least it was when it launched. That’s why I included the “more” part, but since I haven’t used it in years I wanted to give them the benefit of the doubt, because lots of embedded systems come out with slow crappy software that improves over time, and lots ship with the slow crappy software and never get better.

Idk, it’s worth next to nothing to me. Wow these things got cheap on eBay.


@Cody means v.5, not v5.


Incorrect. I don’t dislike you, and I’m not sure where you got that impression.


The existence of the decimal point hands the win over to me. People call the Cortex “V4”, but that doesn’t make it such.

No one I know ever called it v.5, and if you’re really trying to sell the idea that your brain knew about v.5 and V5 and couldn’t figure out which bin “v5” belongs in (when refering to an old system no longer sold) then you have bigger problems. You didn’t know about “v.5”

We gave op all he/she/them/them/their/zir… needed. This thread is done.

I beg to differ. I personally think that I know quite a lot about v.5, but OK.

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@vyuschuk, there are several great things about VEX EDR system.

First, there is a lot of matched mechanical components that are very easy to build / prototype with, if you need a platform that is stronger than Lego Technic or VEX IQ.

Second, if your kids are into robotics and are competitive they may fall in love with VRC and there is a great community that formed around it.

Also, VEX EDR electronics is good for students to get started with out of the box, but it was not designed for easy tinkering or to be interfacing with non-VEX components. Legacy Cortex system is slightly better in that regard, but V5 is nowhere near to the point where it is as open and as well documented as something like Arduino or Raspberry Pi.

The best document, I’ve seen, about interfacing with non-V5 components is the one linked by @majorjoel2

However, it is not for the faint of heart and you will need to have a lot of prior electronics knowledge just to understand it and get started.

If you already know that your children like to tinker with metal parts, screwdrivers, gears, and wheels then VEX EDR V5 could be great platform for them. And if they happen to like V5 and/or get into competitive robotics, then expect yourself to be buying more mechanical parts over the next months and years. But, if you are not sure about their future commitment, then VEX IQ or Lego Mindstorms might be a cheaper alternative to collect dust after a few weeks of initial use.

Personally, I like VEX EDR mechanical system for quick prototyping and getting demonstration models built, but V5 brain and other electronics is too expensive to leave it on a one off models like people usually do with Arduino or other cheaper alternatives.

Unlike V5, older Cortex motors and electronics are much easier to interface with other control systems (Raspberry Pi, Arduino, ESP), which may be something for you to consider.

Here is an example of using EDR motors and mechanical components with NodeMCU/ESP8266 microprocessor module controlled by a cell phone over WiFi: Inexpensive control system for teams without access to Cortex / V5 off-season

If the budget is limited you can get your feet wet in VEX by getting an older Cortex system cheap on eBay, and then, if you like it, keep adding more parts and/or V5 control system if you decide to compete in VRC.


If you run a linux (preferabally ubuntu 18.04) then it’s pretty easy to send ROS messages over the v5 brain via the serial connection with a USB.

This provides a great way to interact with the brain using custom messages. Use this to download to the brain with PROS, and use this to connect with ROS on your computer to the brain and publish the topics.

Just a thought :man_shrugging:


The brain advertises a service with several characteristics, there’s an exchange done where the brain id has to be entered to avoid ad-hoc connections, then you essentially end up with two bidirectional pipes that act the same as the two USB CDC channels. One is for admin messages, to download programs etc. the other is for IO to/from user programs.

As far as user code is concerned, the same stdio commands are used. Using std::cout will direct to whatever is connected, if USB and BLE are both active, then the data will go to both.


@Potatehoes914M ROS and PROS are new to me, thanks.
I get the sense that PROS makes the device less kid-friendly so I probably wouldn’t do that in the very near future.
However(!) it looks like I can give ROS a try with the mBot and Pi3 that we already have and see how that goes.

@sazrocks FWIW I wish I could mark the first reply as a second solution since it seems adding a Pi would indeed add the capability and add even more potential.

@jpearman I see that the VEX IQ supports a Smart Radio module. Should I infer that the IQ could also send/receive messages the same way?

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The radio is locked down, you can’t really do much with the V5 system wirelessly outside of controller communication.

There is one branch of PROS that supports a wireless stdin + stdout, but it has disconnection issues so it’s not recommended.


@djavaisadog Thanks. I assume you are referring just to the wifi (which was indeed my original, uninformed question) and not the bluetooth option mentioned later by others.

Just out of curiosity how hard would it be to plug 1 V5 radio directly into a computer to get (if I handled the r485 stuff) to talk to a V5 over the link.

What would it take to initialize connection?

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