CAN issues with the CANdle

Hey all, we recently installed CTRE’s CANdle and began experiencing significant issues with the rest of our robot. Linked below is a video that demonstrates the following.

  • CAN Bus health is good as indicated by the status leds on the CANdle and CANCoders (orange blinking light has to do with magnet placement but is other wise good)
  • Spark Maxes on swerve modules are not indicating that they are trying to move (as they should be) when they are jittering their way to the desired module state. i.e. the modules are jittery

Things to Note

  1. Our robot was working just fine until the addition of the CANdle to the CAN bus and continues to work when it is removed.
  2. Having reached out to rev during the preseason with regards to the same issue, they said that such behavior with Spark Maxes usually came from poor CAN (wiring, connections, etc.)
  3. Our CANdle was just update to the latest firmware for the 2023 season
  4. Our CANdle is powered via the VRM with 5V 2A (needless to say we are using the 5V addressable leds)
  5. Our CAN wiring is good.
  6. As far as code goes the issue persists even when an instance of the CANdle is never created so I doubt it has to do with this.

If anyone has experienced similar issues or has any ideas on what potential problems may be, any help would be much appreciated.


Yes, and it’s always the CAN wiring.

I presume when you disconnect the CANdle from the CAN bus everything runs well again?

Yeah everything runs fine with the CANdle disconnected.

Just to double-check, the latest firmware for CANdle is Make sure this is the version you have flashed.

CANdle needs a 12 Volt power input.
User manual snippet for reference:

For 5V LEDs, CANdle has a regulated 5V output that can be used. The input power needs to still be 12V though.

If CANdle is being powered by less than the 6 volt minimum it’s very likely the CAN comms hardware is not functioning or functioning incorrectly, which could cause what you’re seeing.

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That would probably explain it :grimacing:. Just a follow up question, if the CANdle has regulated 5V output then could we power the CANdle with something like a mini power module and still see consistent lighting that isn’t susceptible to voltage dips?

Yep, powering CANdle from a battery voltage source is fine.
Just keep in mind the amount of current you’ll be drawing (CANdle can do up to 6 amps but the number of LEDs you have will determine the total) and make sure your hub/PD slot is chosen accordingly.

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My team had the same issues, we ended up just switching the CANDle out and everything was working fine again.

Your power wiring error was more subtle but benign than mine. Plug the wrong end of a POE energized cable into our favorite switch and I got immediately a “$100 fine for smoking indoors.” (The perils of working with a rat’s nest of unlabeled wire.)

Our team has experienced these same CANbus issues when we updated the candle firmware to version Reverting the firmware back to a previous version ( seems to have solved the issue for us.

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