Old radios with new cortext


Wow! Impressive, how did you get this to work? Simply pair the two? I thought that was impossible? Or was this really just another “fake” video? (I doubt it?)

P.S. That link doesn’t seem to want to work, copy and paste it into your address bar or try this: http://www.youtube.com/watch?v=RIusEpkfQzg


We did it with one of our Cortex controllers since the Joysticks are on backorder still. All you need to do is pair them and it works fine (you can pair them in the same usual way by using the USB cable). We didn’t think it would work either but we tried it and it did.

I specifically asked if this was possible and was bluntly told NO.

I want someone from VRI to confirm or deny this one.


That’s what I thought I had remembered seeing… I will have to try this myself, could be quite useful, especially for people who dislike/don’t need or want to pay $150 for a single new controller that has some pretty big problems, I would much rather use the old transmitters personally, as long as it preforms as well as it did with the VEXnet upgrade.


Completely agreed!

Which is why I want VRI to confirm this. We need to know not only if it works but if it works with the competition template and if it’s legal for competition use.


i was there to confirm it :slight_smile:
and no, its not another TBA machine (it was pretty cool though :))

since there were at least THREE threads and debates about how they will “NOT” work together (and an essay on the technical stuff on why they didn’t work) we didnt really want to “try” it - we were scared we might burn something out
but a grade 8 who didn’t know anything about vex just wanted to drive around the robot base around for fun (btw this was 3 weeks ago)
since he was being ignored and the cortex batteries were dead, just just “tried” random controllers lying around (btw he usb-usb’ed all the controllers he tried)
and little did we know, “hey guys, this one works!!”
we all stared at astonishment
at first we thought it was because it was tethered
the next day, we took out the tether and put in usb wifi keys and IT WORKED!!!

this follows the BIGGEST VEX LAW: no theoretical law apply to vex :slight_smile: -electronics, wifi, theory and all
(we found out the rule when we discovered that hypotenuse didn’t work ;))

If this works safely I want to use it. The new controller is really cool and all but for at least the drivetrain I’d prefer the precision (and better battery life) of the old joysticks.

All I can say is that I asked the engineers who designed VEXnet and they said it wouldn’t work. If you want to ask again, put the question in the official Q&A.

It’s not a supported feature.
It (kind of) works right now. I can’t guarantee it will always work. It probably won’t work with easyC or ROBOTC (download and debug won’t work).

It won’t be legal for competition usage.



I am curious as to your reference to “all the problems” that the VEXnet joystick is having. Could you send me as detailed a list as possible of the problems you have observed?

My e-mail is paul_copioli vexrobotics.com



The two biggest issues regarding the VEXnet Joysticks have been discussed on these forums numerous times.

  1. The excessive battery drain. I feel this needs emphasized, the VEXnet Joystick’s eat batteries way faster than said batteries can be charged! This is a huge problem.

  2. The inaccuracies of the actual joysticks on the VEXnet Joystick as discussed in this topic.

We need battery capacity and accuracy, period! Some of us have designs more complicated than the Protobot…

I’ll go ahead and e-mail this to you with a link back to this topic.

Thanks very much for listening to the community,

:open_mouth: i just noticed that you are not an “IFI” staff anymore
did something happen?

umm, i didnt ask for the cortex but our mentor ordered it anyways (waste of $350 if you ask me) and have caused MANY HOURS of headaches!

another thing, what is the advantage of the cortex???
i have had it since the beginning of the year and dont find any noticeable difference… (other than its smaller than the vexnet upgrade kit)

the loading speed is noticeable but not that much different
the “memory” is theoretically bigger but i had a retardedly long autonomous last year (i was a novice programmer then) that was an equivalent of 6 different FULL 20 SEC autonomous
it also took over 1 min to compile
and i still did not hit the “memory limit”
hardly doubt i would ever need the extra space in the cortex…
the programming functions are also A LOT harder to understand (analog and digital joystick functions are separate now, and has A LOT of confusing settings that must be inputed)

the ONLY good thing that i personally thought was better was that there was a “holonomic drive” function block
we’ll probably use that sometime this year

just my 2 cents

I’ve filled the memory many times… It’s rather annoying on the v.5…
In addition to that: faster processor, more sensor ports, native 2-wire ports, 2 4A breakers instead of just 1, what’s not to like about the controller?

The Cortex is a superior microcontroller, hands down. More memory, CPU, I/O, higher max power output, etc.

Admittedly, the software end of things was far from stable during the college beta but I assumed most of those problems have been dealt with by now.

My intent here isn’t to bicker or complain, or shoot down the hard work of VEX. This is constructive criticism aimed at bettering the VEX platform. Honestly, you guys pretty much know that I won’t touch the FTC “platform” with a thirty-foot pole. VEX is booming. We’re just nit-picking small details so that we end up with a flawless kit that just works.

I hope that makes sense,

I largely share the sentiments of Cody here. Vex largely comes out with great stuff but the controller is annoying for many competition applications, particularly ones that push Vex to its limits. What I particularly like about Vex / IFI as a whole is that they’re willing to listen to feedback. That the President of Vex Robotics would come on some random message board and invite someone to e-mail him with their detailed concerns about a product is in my book pretty dang cool.

Other than the controller and normal adjusting to new hardware bumps and glitches I’ve had no problem with my Cortex. I’m not exactly a huge software guy but the more integrated VexNet controls, backup battery, and memory increases are pretty helpful! (Now to work on that gamepad’s battery life…)


*]VEXnet bi-directional wireless communication (based on 802.11g)
*]Wireless driving, wireless debugging, and wireless downloading
*]Also support for two 75MHz crystal transmitters and receivers
*]STMicroelectronics ARM Cortex-M3 user processor
*]90 MIPS performance (9x the V0.5 microcontroller)
*]384KB Flash (12x the V0.5 microcontroller)
*]64KB RAM (35x the V0.5 microcontroller)
*]easyC for Cortex and ROBOTC programmable
*]One I2C port (will connect to multiple new smart sensors)
*]Two fast UART serial ports
*]8 high resolution analog inputs (12bit)
*]12 fast digital I/O (all can be interrupts)
*]10 motor ports
*]8 standard 3-wire PWM
*]2 new 2-wire motor ports
*]Motor current limit is 2x original controller
*]DAC speaker output (sound, voice, music output to external speaker)
*]Latches on all 2-wire and 3-wire IO sockets
*]Same size as VEX Microcontroller V0.5

In my experience, the downloading time is much faster, a couple seconds as opposed to over half a minute. Although mastercode takes over a minute to download, firmware is much faster, and downloading code is fast as well.

Just by using it I have noticed the memory change, we maxed out the memory in the PIC last year, and had to cut a lot of our autonomous functions to be able to stay within the allowed memory. We currently have more lines of code than we did at all last year and still don’t have much of any autonomous code, but have not yet maxed out the Cortex, and I doubt anyone really will for VRC.

Not sure about easyC, but RobotC hasn’t changed much… As for analog/digital, I don’t find it too hard to know which one needs to be used for a sensor…

I have found a lot of good with the Cortex, and although I dislike the new transmitters, I would never go back to the old PIC controller again.



We love all the feedback and don’t really mind the nitpicking as long as you don’t mind us blowing off some of the more nitpicky stuff:)

Regarding the topic of the old transmitter with the Cortex using VEXnet …

There is a BIG difference between “Hey, I got it to work!” and “The old transmitter with 1.5 plus Cortex is a working solution supported by VEX Robotics.”

When we were developing the final configurations of the Cortex we made a decision (the executives at VEX and our owner Innovation First International) to not support the old transmitter + 1.5 with Cortex. The reason was simple: 1.5 has an entirely different set of master code to make sure the communications protocol to the PIC was robust. Supporting both the VEXnet Joystick and 1.5 transmitter will hurt our total customer support ability.

In addition, I firmly believe that classroom applications do not need VEXnet and the PIC curriculum will fit many classroom teachers’ needs. I also firmly believe that the new joystick with Cortex is the better solution for competition teams.

The new joystick may take some getting used to, but in my experience with my own FRC team the drivers will be much better with the Logitech style joystick than with the old RC car joystick. It does take some practice, but we truly believe the new joystick / Cortex combination is far superior to our previous solution for competition.


We’ve only had the Cortex and new transmitters a few weeks. (We waited for the upgrade!) We’ve been through one competition (NW Maryland).

Our experience with the Cortex is good except for loosing the VEXnet connection. At the Competition, all worked perfectly until the semi finals when the referees decided to put the sizing box on our robot. It fit, but after that the connection would only stay for a few seconds. After loosing the first match without moving, we tried changing all the batteries. Still the connection would connect successfully for a few seconds and then drop out. One of our partners suggested resyncing and changing VEXnet keys. This worked and we were able to play the next match. So what caused this and how do we avoid it? In our single attemp to use these keys at home we got no connection at all. Again they had worked fine in competition through all of the qualifying rounds.

Our experience with the hand held tranmitters is mixed. It takes a lot more programming to get satisfying driving results. This is not a big deal for us but it could be for rookie teams. The battery issue is a big deal. Instead of dealing with four batteries we now have 100 to deal with. And changing them is far harder. Needing a screwdriver to change the batteries is a bad feature. We used 36 batteries at the tournament but only made it to the semi finals. I am sure we would have used 24 more if we made it to the finals.

Jon T