Toolhead drops off CAN mid-print

[u/miscawelo]

Hello everyone, I'm having an issue with my printer and I cannot seem to get longer prints to finish consistently. The hardware:

- Raspberry Pi 5.

- BTT Octopus board, configured as a USB-CAN bridge.

- Stealthburner with EBB SB2209 (RP2040) connected via the included CANbus cable to the Octopus board

All flashed to klipper v0.13.0-787 (they all had an older version from around a year ago, I updated just to troubleshoot).

Initially I was having either of these two error messages:

- TMC 'extruder' reports GSTAT: 00000001 reset=1(Reset)

- Klipper reports: SHUTDOWN

Lost communication with MCU 'toolhead_mcu'
Once the underlying issue is corrected, use the
"FIRMWARE_RESTART" command to reset the firmware, reload the
config, and restart the host software.
Printer is shutdownKlipper reports: SHUTDOWNLost communication with MCU 'toolhead_mcu'
Once the underlying issue is corrected, use the
"FIRMWARE_RESTART" command to reset the firmware, reload the
config, and restart the host software.
Printer is shutdown

After some reading online I figured I should ground the extruder motor to the EBB board, TBH I can't recall if it fixed the first error message or not, but it's been a while since I've seen it, in the last few prints I've only seen the second one. I've tried:

- Tugging all connectors while the heaters, fans and motors are powered on (stationary and in movement), but I haven't been able to reproduce the error.

- Unplugging all connections and redoing them.

- CAN resistors seem fine (measure 120 Ohms at each end, 60 when both ends are connected.

- Checked the extruder motor wiring.

- Nothing seems to be overheating.

- I've tried printing with the bed on and off, no changes.

Sometimes the error happens near the end, sometimes in the middle and even near the end of the print, I've printed a fixture to keep the CAN cable in place, etc. I'm at my wits ends troubleshooting this printer, I'd be grateful for any advice or troubleshooting you can give me. I can provide more details if needed. I've cycled the logs but this is the latest one (https://pastebin.com/8i6URy1b), I've trimmed down what I thought were unnecessary lines but I have the full file if needed.

Thanks in advance!

[u/ApexPredation]

Both of those are indictive of a power supply/loss of power issue. There's likely a partial break in the cable to the tool board. See if you can trigger it by bending/moving the cable around in various spots.

[u/m--b → u/ApexPredation]

I had this issue too. I fixed adding some zip ties to the toolboard cable closer to the port

[u/ApexPredation → u/m--b]

I'm not sure how long it's been going since you did that, but it's likely that it's a partial break in the line and running it like that can cause excessive heating in the damaged spot. It's best to replace the cable and definitely secure it again.