VEX IQ Tournaments - IQ Controller and Brain dropping connections randomly multiple robots

IQ tournaments and meets - having issue with random robots dropping the connection between the controller and the brain. Moved all other devices (laptops for tournament manager, WiFi, Raspberry PI for monitors, etc.) to 5GHz range to eliminate congestion. We had a tournament of 44 teams yesterday; about 5 - 10 times controller would drop connection to the brain. The drop is random - not tied to a single robot (eliminating hardware issue). Question - has anyone had congestion issues where several robots close proximity causes / drops (2.4 has 3 channels) a brain/controller connection? When firmware updates occur, does it update the radio also or only the brain, controller, and motor firmwares? My background remote chance the 5Ghz frequency is in the same range (20Hz, 40Hz) as the brain / controller 2.4 connection causing interference, but not sure. I think we eliminated hardware issue - as it happens to different robots different times. Eliminated general environment as out of over 320 matches only occurred 5-10 times (but still bad for that team). We believe all were gen 2 brains/controllers, but not sure. We know at least 3 were Gen 2 from our group. Thoughts? Would 5.2Ghz frequency be conflicting (but then it should be more consistent) in the 20 and 40Hz range causing the 2.4 radios on the brain/controller issues? Grasping right now - as it happens often enough to cause frustration for teams, etc. All robots should be latest firmware; but not sure if that would impact connectivity between brain/controller. Teams that came to field were connected, then dropped. Some volume at/around field, but no more than the pits for 44 teams within 10 feet of eachother.

Thoughts? Input?

Try calling Vex Support about this
If Some are Gen 1 (this is gonna sound terrible, but we had to do this last year), use an ethernet cable. The big blue cables that plug into the Gen 1 brains and the controllers (I’m pretty sure that’s what they are called I just don’t want to be wrong about it :sweat_smile: )

I’ve not seen this with IQ, I just ran an event with 3 fields, three matches at a time with the fields only 4’ apart. 22 total teams in a small cafeteria.

Firmware updates are on as needed basis by device. I just bought some motors from a defunct team and when I put them on a current brain it only updated them.

For V1 brains here is the change log. 2020 was the last update for it.

V2 Change Log

That is a key piece of information that helps tech support quite a bit. I only have about a dozen V2 brains, we keep them up to date on the firmware. I’ve not seen radio issues.

No, the harmonics of a 5.2 Ghz radio and a 2.4Ghz radio are not going to collide unless there is a great deal of splatter. The radios are on pretty tight bandwidth.

The only thing I can think radio wise if you have an ancient Amana Radarange ™ microwave oven that is splattering a high level signal all over the place. As an amateur radio operator poorly built / shielded microwaves used to be an issue.

I’m more inclined to suspect controllers that are not fully charged. That I’ve seen more times than I wish.

(An aside, I’m pretty impressed with 320 matches. How many fields for how many hours?)


Thanks @foster!

Still wondering what is causing the issue but this helps.

No idea if controller was fully charged or not; but once controller was paired with brain again (not sure if they shut everything done to reconnect or if they had to pare the controller to brain as I was judging).

Change log for gen 2 1.0.6:

  • Improved robustness of radio communications during program downloads via controller.“

Was that just a buffer size or a tweak to the brain radio? (Would this create a possible hiccup with brain/controller connectivity?).

FYI for the question about the tournament - directors have done this over 18 years and a great support team around them. We ran 8 qualifying matches for 44 teams;6 skills per team and 8 finals Saturday.

Forgot to add: 3 team fields; 4 skills fields; and 3 practice fields.

Had 2 late adds for 44 teams (344 qualifying rounds; 264 skills (I think), and 8 finals.

Went 8-4:30 but I think we got done early even with an internet drop in the morning.

A few comments and clarifications.

controller to brain connection is BLE, so many channels.

generally it won’t, but it’s best to be on the latest.

A firmware update for a generation 2 brain will also update the radio if needed. It will show a warning if the controller needs an update, but that is then done using VEXcode.

This was related to buffer sizes and improved error checking when packets were lost, only impacted downloading a user program to the brain wirelessly via the controller. Nothing to do with the actual radio connection.

If you read back through the forum you will find that every year we get unexplained radio disconnects. With V5 it can be physical problems with the robot, loose connections etc. but generally is most likely due to environmental issues, too many interfering RF sources in the same 2.4GHz band. Things like microwave ovens being too close.

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Thank you!

We have eliminated any other 2.4Ghz in the environment part of it $$$ to convert). All other wireless on 5Ghz channel. No microwave or any other equipment in the area (3 basketball courts wide). Closest kitchen “room” (pop machine, vending machine, possibly a brand new microwave about 100-150’ away buffered by 3 concrete walls. Out of 44 teams Saturday occurred to different teams /different times. There was minimal interference (trusses for broadcasting, middle school fields on elevated plastic platforms, etc. Typical competition environment (3 team fields, 4 skills, 3 practice field 2 basketball courts away. No walls in the way. School wireless was moved to 5ghz to eliminate interference a couple months ago. TM and Pi’s I am told on a small 5Ghz network ($300 WiFi router in proximity to fields with 2.4 disabled).

What do you think could cause a controller to drop connection in IQ in an open environment? Gen 2 equipment. All firmware updates (can at least vouch Grandville teams fully patched); etc.


Are you sure these were all radio disconnects ?

I don’t really have any further thoughts. It’s unlikely to ever be perfect, many phones, iPads, fitbits etc. all using same RF space. 5 drops out of 320 matches may just be the limit of what’s achievable, I really don’t know.

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Thanks @jpearman for looking into it. I’ll pass along. I was told the controllers were connected; went to compete and were not connected. From conversations the controller had to be reconnected and/or paired again to brain. As you can see minimal equipment in proximity to the queue tables between middle school fields.

I’ll pass along and thanks for input. As you can imagine very frustrating for teams and caused delays 5 times Saturday.