Cortex Questions

I recently bought a new Cortex microcontroller, and to be honest I am very let down. My PIC microcontroller broke 4 months ago and instead of buying a new PIC, I waited for the Cortex to come out, obviously I was really excited to buy the Cortex. However I have had some problems/disappointments with the Cortex…:

  1. Range- I have done a few tests and it seems like the old crystal system had way better range then the new VEXnet system. I am not sure if this is just the nature of wifi technology but I would think that this would have the same if not better range since it is newer technology.

  2. Pairing- From what I have read, I think I have the VEXnet system paired correctly. However every time I turn on my Cortex it takes about 10 seconds to pair up the joystick and microcontroller and my motors always spin randomly before the connection is made. I would expect that the second you turn the Cortex on it should be paired, similarly to the old crystal system.

  3. EasyC support- The new EasyC v4 is great, it has a lot of cool features however it seems to be lacking some major components. There is no support for the speaker port or the crystal system. And also the online window seems a little laggy.

I realize that the Cortex is very new and a lot of components are still in beta testing but I am just very disappointed after waiting many months and spending $400. I was wondering if anyone else was having any problems or any comments in general about the new Cortex.



  1. range:
    im pretty sure wifi can go further than crystal
    wait and see if someone can give you troubleshooting steps or something
    im not that clear about the system myself…

  2. pairing
    when i switched to vexnet i felt it too
    but you’ll get used to it in like a week
    dont worry too much about it
    (for that, you will NEVER get interference again)
    just my 2 cents

Actually in my experience vexnet does not have the range that the crystals do. I think the Vexnet system was designed more for competitions than anyting else.

About the pairing. The manual says that it will take about 15 seconds to pair every time you start it up.

Hopefully support for using crystals wil apear in the next release of EasyC v4.

I’ve gotten better range with obstacles and corners and stuff using Vexnet. I don’t test the limits very much (usually in the same room, line of sight) but I’ve never had a problem with Vexnet range.

10 seconds isn’t that much time, really… If you need to drive something faster I just tether.

I can’t say I’m disappointed (I got mine for free :D), but the advantages of the Cortex aren’t the kind of advantages I would just randomly spend $400 on to get. They are really nice and awesome and appreciated, just more subtle. Like the PWM snap holders, more room for code than I will ever need, faster processor, etc.

10s is not too long to wait, but having the motors spin randomly is a big problem. During this time, your limit switches, etc, are not honored. They need to fix the firmware to ensure the motors stay off until ordered to run under program or operator control.


  • Dean

Does this happen? I have been running the default code and haven’t experienced anything like this. Can you fix this in code somehow?

It has happened to me - nearly stripped some gears on an arm drive mechanism because the limit inputs were ignored. Once the link is established, the motors operate under program control. I haven’t found any way to work around this in code.

It is possible that the latest firmware upgrade or EasyC addresses this, but I haven’t been able to run it because my beta license has expired and there does not appear to be a way to buy v4 licenses yet.


  • Dean

Is there a way you can check with an if statement if the controller is connected, and only run the motors if this is the case?

Well, the if statements that prevent the arm traveling past its limits wasn’t working. It really seems like my program didn’t start until the link was established.

I just upgraded to EasyC hoping that would fix the problem, but this seems to have invalidated my license, and it isn’t giving me a trial period, so I’m at a loss to try anything else till I get the license issue sorted out.


  • Dean

I agree 100%. The Cortex nearly destroyed our eight motor holonomic drive last season. WE never knew if the random movements were being caused by our program somehow or the Cortex.


Intelitek was able to resolve my license issue this morning, and I’m happy to report that the upgrade to EasyC has resolved this problem for me.

The motors are now off during the link-up period. The link-up seems a bit quicker too - perhaps because I’m not watching my gears be destroyed :wink:

I hadn’t seen random motor movement except during the link-up period. Are you saying that it would randomly run your motors while under program control?

  • Dean

For those of you posting range concerns, can you please let me know your range expectations and the actual maximum range you are seeing?

If you need a trial key please send an e-mail to

The lag in the online window is only in the Beta versions of V4. If you update the online window response time is much improved. Also, the motors running issue is also a BETA issue, they should not run with the released version of easyC.

The speaker will be supported once the product is released.

I have not been able to test outside or “line-of-sight” control but what I am disappointed about is obstructed signal paths, (ex: in a house with multiple walls in between the robot and joystick). With the old crystals, although it was a little glitchy, I could drive nearly 4 rooms away, or 4 walls in between the transmitter and microcontroller. Now with VEXnet if there are 2 walls in between the joystick and Cortex, I have NO control, the LEDs go red.

Although it is a feature for the new ARM microcontroller it would be nice if we could somehow use our home wifi router to communicate with the VEXnet key plugged into the Cortex. I know this probably isn’t any where close to happening in the near future but it is just an idea.