Communication Errors at BattleCry 20

Technical
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#1

Hey CD, I’m from FRC Team 172 and this is for all who have attended BattleCry 20 @ WPI this past weekend.

If you didn’t watch any of our matches or weren’t paying attention, our robot’s radio would randomly reboot and lose comms almost immediately after the beginning of matches and we would be dead in the water almost the entire time. We’ve done everything we could to make sure that the radio is properly secured and nothing is interfering with it, we’ve also made sure that the correct amount of power is reaching the radio yet nothing changes. If someone could give me some tips on how to fix this, it would be greatly appreciated!

#2

I’d suggest taking a look at my “why your electronics aren’t working” writeup here and make sure you’ve done all of the stuff there. Any number of problems there could be causing the radio to reset.

If you can post your driver station logs here, that will also help narrow down what could be causing the problem.

#3

I’ll try to get the logs tonight, and I’ll make sure to read that post. Thank you.

1 Like
#4

Summary of events:

  • Q 5 - No issues
  • Q 14 - No issues
  • Q 20 - No issues
  • Q 29 - No issues
  • Q 40 - Radio loss from T120 - T80; Packet loss briefly at T60
  • Q 52 - Radio loss from T100 - T52
  • Q 61 - Radio loss from A2 - T87; Radio loss from T78 - T24
  • Q 66 - Radio loss from T130 - T78; Radio loss from T64 - End
  • QF 3 - Radio loss from T103 - T50

It looks like something happened around match 29 to cause the issue. I am fairly certain we checked the electrical system (loose battery nut; automotive breaker correctly inserted; wires completely inserted into PDP/PCM pathway) as one of the troubleshooting steps at the event. This is a good candidate for a radio replacement however this tool is not available to CSAs at offseason events.

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#5

I don’t think it’s a problem with the radio. We replaced it with a brand new, unused one and we still experienced issues. We’re thinking it might be a problem with our RoboRIO or something to do with power.

#6

Ah. I was unaware of that. Seems like it is a power issue as you suggest.

Was your team the one that had the radio mounted upside down on a top cross member with the POE connector? If so: your team was putting a lot of stress on the ethernet connection. Consider some stress relief and replacing the orange POE connector. Also consider doubling up by using both the barrel connector and POE injector.

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#7

Yes we were that team. I will talk talk with my team about replacing the connector and doubling up. Thanks for the help!

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#8

FYI, we had a series of mysterious packet loss problems at worlds, which we finally tracked down to a kink in our ethernet cable that was causing intermittent disconnects. We replaced it and the problem vanished. Ethernet cables often don’t stand up well to the abuse they see on FRC robots–even when you get the expensive ones!

Replacing that cable is definitely worth trying, and running a barrel connector in parallel will help protect you from power dropouts.

#9

Alright, thanks for the info.

#10

Check for metal shavings in the Rio. We had similar symptoms a few years back. Super fine dust can cause major issues

#11

Will do. Thanks.

#12

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