Vex Controller with FRC Robot

Hello CD,

In our robotics class we have a ton of Vex Controllers and the software for the controllers. Also we have a lot of scrap aluminum, chassis and pretty much we are stocked with KOP items from the past 6 years. We thought of making it so our Robotics class gets the chance to rebuild some of our old bots and current team members would teach the class. But one of the main problems is that we don’t want to fork out 2k plus for a whole set of electronics for only one bot. We have old Breakout boards, motors, speed controllers and other items needed for a FRC size robot. Soooo…

Is there anyway to interface the VEX controller so it powers pretty much a FRC SIZE bot with FRC motors and pneumatics? If not, what would be a cheap alternative to a controller and easily programmable.



I can’t find the thread or the post any where, pretty sure this was mentioned

I have done this. You can run two batteries, one for vex and one for IFI or you can build a power supply to convert the 12v power to power the vex.

This was back in 2006.

We haven’t finished the voltage regulator work yet that was suggested by another poster and need to tidy up the wiring but our 2005 FRC robot which was later redesigned to shoot tee shirts underwent a two day conversion to a VEX controller after World Champions this year. You can see it throwing out the first pitch in CD-Media. Victor speed controllers wire up directly to the VEX controller but one needs to make a custom PWM cable for the spikes as these have two signal wires and a ground and draw power from the device power supply. (meaning the +12 from the power distribution)

So if you have spikes you will need to need to wire custom versions going from one connection to two. Does this make sense:confused:

Thank you for the replies. Both Posts were understandable. So I take it that it can be done and it works well. I was looking at the other post and I believe Art said that the VEX and IFI controller are about the same. We will be trying to interface the controller very soon. Thanks for the info and anything else aka more information about the process would be very helpful.


Here you can read a thread by Squirrel which makes the 12VDC to 8 VDC conversion painlessly simple.

Using a Vex controller is an interesting idea… I was never comfortable with the idea of using a PS2 type controller for FRC, with such little range in the joysticks allowing for what I’d imagine to be less fine tune control. The Vex. joysticks seem much better suited to this kind of task.

Has anyone tried both and want to weigh in?

The PS2 controllers work GREAT on an FRC bot. We’ve used them for the past two years and the drivers are much happier with them than with the joysticks, mostly because holding the controller allows the driver(s) to move around to get a better view (especially last year with the glare on the divider)… and to always have the controller at the correct height.

We put the x axis on one thumb stick and the y on the other, which makes going straight really easy… or just sitting there and turning. Fine control over the short throws hasn’t been an issue… no more so than it is when playing a video game, at least. On top of that, I suspect most FRC driving is done with the throttles “wide open”.

The VEX controllers work great, too, and if you look at the new VEXnet wi-fi adaptors that are coming out, the VEX platform gets even more appealing.


It is also very easy to retune an analog breakout to create 8V. All you need to do is change the resistor divider.

See the bottom of page 14 :

Hey RC,

Well since all the info you need is here, which robot will you be rebuilding and why? Just curious.

So yeah we are rebuilding this bad boy:

I like how teams keep their old bots running (47 and 191) and having them around just for show. This robot was just too hard to manage and just got torn up right after season was over. Our 2008 and 2009 robots have required hardly any maintenance. The 07 bot is in seperate pieces, all we have to do is sand down the frame, model the bot using CAD, and start teaching the new ones.

The main reason for building it is because I personally loved the game and we have that summer program. So when I’m not teaching CAD, i’ll be getting newer members involved by rebuilding the 07 bot in 10 weeks (hopefully).