MCU Timer too close, plus other errors

General Discussion
1

Basic Information:

Printer Model: Modified Tron XY400 (Paladin variant)
MCU / Printerboard: SKR3EZ with EZ2209s, BD sensor, BTT HDMI 5, Webcam
Host / SBC: BTT pi V1.2
klippy.log (1).txt (1.7 MB)

Describe your issue:

I have had this printer in the same configuration for over a year, and printed over 100 days worth with no issues. Then it started failing mid print for “MCU: Timer too close”. Not always in the same place, or after a certain amount of time. Seemed random, and sometimes it would take 3 tries to finish a print.

Also started getting “tmc_uart response” errors, but I believe those are cascading from the timer too close. Recently got a “lost connection to MCU” error, but that’s uncommon.

While watching the print, the pi doesn’t overheat or even show high loads. I put a box fan on the electronics to confirm it’s not a heat issue with no change. I was several commits behind on Klipper, so I updated everything (including firmware with BD sensor recompile), but that didn’t seem to help either.

Things I’ve tried:
Updated everything
Cooled electronics
Changed webcam
Unplugged webcam
New USB cord

Does it seem like a hardware issue? What’s my next step?
I have a brand new SKR 1.4 turbo in the box with new 2209s and I’m tempted to swap it over but my research says it’s more the pi.

SOLVED:
I ended up swapping boards over to a new SKR 1.4 Turbo from a SKR 3EZ. During this, I found that one of my stepper motor connectors was loose and would lose connection randomly. I don’t know if this is the root cause, but I fixed it, and I’ve been printing for 5 hours with the new board and no issues. Hopefully that’s all it was.

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Git version: 'v0.12.0-401-g383b83d78-dirty'
Untracked files: klippy/extras/BDsensor.py

You may try with a clean version.

grafik
grafik277×271 1.79 KB

You may check the bed heater and/or bed thermistor wiring

It also seems, that there is a quite unreliable connection to the MCU

3

Good catches.
Unfortunately, the BD sensor requires a custom compilation of Klipper and I have to compile it with the BD sensor additions which I believe will make it forever dirty. However, it has been that way for a long time with no issues.

And yes, while I was changing USB cords, I knocked the bed thermistor loose and got that error but that was a user error.

For the unreliable connection to MCU, what suggestions do you have? I just swapped USB cables, but I could reflash the pi.

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Any other thoughts? I’m about to start replacing parts, but would rather use some logic if available.