V5 radio LEDs turned red in the middle of competition

At our state championship, my student’s V5 radio changed from blinking green to blinking red in the middle of the match. Nobody noticed until after I reviewed the video I took of the match. As a result, my student was able to get about an extra half second of driving and climbed the middle platform. He stopped at what we all believed to be the buzzer, but the losing alliance complained that he drove after their robots stopped moving. Head ref accused my student of cheating and he teamed up with an opposing alliance coach and the host of the event to DQ us. Others intervened, voices of reason prevailed at the time, REC officials were called and after a long deliberation it was officially ruled that because the last half second was not match affecting (our alliance would have won by points anyway without the high park) the score stands and our alliance wins. Fast forward to present time, the coaches of the losing alliance said they have “eyewitness testimony” they presented to the REC Foundation. One of the allegations is that my student disconnected his controller on purpose (pulled the wire out) so he can drive past the buzzer. REC emailed me and said they are considering DQ-ing my student. I have a hi-res video of the match and of the 30 minutes after the match that shows that they are wrong, so someone is actually lying in order to qualify their teams. Not only the controller was plugged into the tower all the way to the very end of the match but there is nothing showing anyone or anything even tugging or touching that cable. If my student is DQ-ed, the opposing alliance goes to Worlds.

My question is not why even in robotics you see this kind of petty behavior - instead of celebrating kids being awesome, people get upset that they lost and drag you through mud. My question is technical:

What would cause the behavior I described above. Everything plugged in properly, match starts normal with green leds blinking. Then in the middle of match radio leds start blinking red. No indication of malfunction on the controller, everything works, cables are attached. V5 is flashed with 1.0.5 on all components. Programming is done through Robot Mesh Studio Python with standard competition template code.

Somewhere buried in this forum is a jpearman explanation of how field control works. According to that, all field control does is send signals to enable/disable motors.

What is the purpose of the green light blinking (vs. red light blinking which I’m told means connection established)?

Shouldn’t the robot stop responding when the lights blink red instead of green in the middle of a competition?

Is it possible to achieve this kind of behavior from the laptop/software that controls the match (sorry, the opposing team’s coach was around the field software laptops, not ruling out anything)?

Can a faulty jack, faulty Ethernet cable, bad connection to tower, someone stepping on a cable, a solar flare, etc. do that?

Sorry for so many questions and thanks. Just trying to clear my student’s name.

Going green to red would suggest it was disconnected from field control so either not fully plugged in or perhaps a broken cable.

The green light blinking means that the robot is 1) enabled threw the tower and 2) that it is connected to the controller. If their alliance robot did not disconnect, then it is very unlikely that it is the field control. A faulty ethernet cable could be the culprit, but if the robot had been functioning up to the point of disconnection, that is unlikely as well. As far as the computer that controls the field, the only thing that can happen while a match is running is for the operator to stop the match, which would obviously effect all 4 robots on the field. There are several things that could have gone wrong, but I have not seen a fault (so far) that allows a robot to continue after the match ends, unless they had lost connection to the tower, which may have been caused by a cable coming loose or disconnected.

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I would suspect this is probably the cause, faulty cable, they get stepped on and yanked a lot. That said, it would be good to know RMS behavior when you unplug from the field, does it stay in driver control? You can test this in your shop.

Also at the SNE HS Regional I saw a robot with blinking red and not green lights. The robot had been inspected for current OS, so we are not sure what was going on there.

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How I read the schematic the field controller simply ground 2 pins - one for autonomous and the other for competition
00 - disabled
10 - competition
11 - autonomous

There is a big issue w/Cortex controllers where the little tab on the RJ-45 Female breaks and the Male doesn’t stay in. I imagine the same can happen w/V5. However this stops the robot mid-match , not let it run.

As far as sportsmanship. We noticed the same nit-picking, petty bickering as well (South Carolina). Best we can figure it is because this year’s competition is so lame and low-scoring no one was happy.

I also suspect when adults are the one raising a fuss (not students) chances are they are the ones who did most of the work. But IDK.

End of the day, what the coaches rule then will be final. Let them belly-ache and whine all they want, you have precedent and evidence to the contrary!

GL at worlds!

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The behavior you described (v5 radio light changes in color from green to red, but robot does not get disabled) is consistent with what would happen if the controller became unplugged from the field mid-match. It’s not uncommon for the ethernet cables connecting your controller to the field to have somewhat loose connections due to normal wear & tear (they get plugged/unplugged pretty frequently) and/or being stepped on. Given the right conditions, it’s probably possible for a cable to become electrically disconnected/loose without looking like it’s unplugged. Sounds to me like that’s what happened in this case.

It’s hard to say for sure without being there, but based on your description, this does not sound like the sort of thing that should warrant a DQ, particularly if the driver obviously wasn’t trying to cheat, and the points allegedly scored after t=0 didn’t change the winner anyway.

At a small local competition this season, I saw a match where a competitor’s robot kept moving after the other robots were disabled (note - the team moving was clearly as surprised as anyone else!). I’m pretty sure the robot was using Cortex, and from an outside observers point-of-view it appeared that everything was attached correctly by all robots on the field. This was after several other technical issues with the same match on the same field and the determination (as far as I’m aware) was field-fault (very low-stakes - an early qual match).

That same field cause endless problems throughout the day for many teams (in fact it was so bad that my team brought it up with the EP and requested that the field be double checked & possibly taken out of play for finals after we had 2 separate qual matches on it with disconnect issues on the same tower same spot). We spent some time discussing it with other people present (competitors, mentors, EP, etc) and, while nothing was ever truly resolved, I personally was leaning towards it being a faulty field cable.

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If the park was not match affecting, then it’s pretty clear from past rulings and the rules that no further action is necessary and that the team should not be DQed.

The lights changing to red does indicate that the field control came unplugged (probably from the “game” pin becoming disconnected).

The most concerning aspect of this however, is that the RECF is seemingly again violating T01:

and this is in spite of the GDC’s recent ruling that this is against policy:
Gonna tag @DanMantz for comment on this.


Three conditions need to be met for green flashing radio led.

  1. field controller connected.
  2. radio and controller are linked.
  3. user program is running.

if 3 was invalid then robot would not drive, if 2 was invalid the led would actually be solid red and robot also would not drive. So that leaves case 1, field control was disconnected somehow.

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James, at SNE Regionals this past weekend we have a robot with VEXos 1.0.5 have flashing red radio and under field control. Your conditions for having green flashing is the positive, is there any situation you could imagine where all three are met and flashing red?

I brought this to the attention of the referees, but the match was waved on at the time. Since it was not my event, I could not intervene to get more diagnostic information.

There isn’t supposed to be, I have seen situations where the led should be flashing but is solid, this could happen if radio on the robot was disconnected from power very briefly but then often there was also no connection to the controller** (fixed in 1.0.6 to be released soon). Most likely would be student not having run a program, I see them do this occasionally if they don’t want to run their autonomous for some reason.

** and nothing to do with the other mysterious disconnect issues that have been reported.

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I have noticed that if you enable autonomous with the Competition Switch and unplug the switch on V5 that autonomous will continue to run. A similar thing could happen if the field controllers are electrically similar to the Competition Switch. This appears to be a result of the normally open state of the slide switches used on the Competition Switch

Yes, that’s expected behavior.

Isn’t that potentially dangerous if your autonomous malfunctions and this occurs? At least on V5 it hard to stop a robot that is driving erratically and trying to shoot at the same time.

If the competition cable is disconnected you can still stop the program from running using the controller power button, but I agree, this is something we should probably look at again and perhaps improve. My recollection is that it’s the same behavior as the cortex, that was the intention, but perhaps we got that wrong.

Fair enough. We often holds the controller or have a team member hold it during auton for this very reason. Just found it odd how the switches were electrically setup

I find it totally reasonable that the V5 hardware and firmware could be at fault. At one of my early season regional competitions they forced everyone to update their firmware then and there because of a overnight patch (You could drive in the autonomous period) Also, a team had a white screen in a match we played, their flywheel was running at the time of the white screen and the flywheel continued to run even after all robots were disabled.

@CSpencer The issue with the white screen is static related. There is an official VEX advisory about this if I remember correctly. @jpearman ,feel free to correct me if I am wrong