Lost communication with MCU and MCU shutdown: Timer too close after updating

General Discussion
1

Basic Information:

Printer Model:
MCU / Printerboard:
Host / SBC
klippy.log

Fill out above information and in all cases attach your klippy.log file (use zip to compress it, if too big). Pasting your printer.cfg is not needed
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Describe your issue:

Hey everyone,

I have a Prusa i3 MK3S+ modified with a Rasperry Pi 4 to run Klipper. I am using Fluidd as my interface. This modification was done a few years ago and has been working well ever since. For the most part this is a stock MK3S+ with only a few exceptions:

  • 3.5” Pi TFT Touchscreen connected directly to the Pi using GPIO running Klipperscreen
  • Logitech Webcam connected to the Pi via Crowsnest
  • X and Y Motors replaced with 0.9° Steppers to reduce VFA (New)

I recently upgraded the X and Y motors, but until recently they seemed to be working fine. I do think this might be a potential source of the problem, since I am using the standard EinsyRambo board over USB, which is just an ATMEGA2560 so it is not very fast, but I am not sure. The errors seem to indicate a problem elsewhere.

I have been trying to run these motors fairly fast, with a max speed of 250mm/s and max acceleration of 4000, but I am not sure if this is too much for the mcu.

Originally I thought that the problem was caused by the Pi running out of resources, so I have disabled Klipperscreen and Crowsnest, but the problem still persists.

Running top and htop shows very little CPU and memory usage, and there is nothing else that I can see running on the Pi. That being said, the “System Load” on fluidd always shows ~2/4 even when the printer is just idling and heating up.

I have tried slowing the speeds down to 200mm/s and the problem still occurs, and occurs seemingly randomly in the print.

If anyone has any idea where the problem is here, your help would be greatly appreciated. Thank you!

klippy.log.zip (2.2 MB)

2

Just a blind guess, there were some recent fixes.
So just try to update further.

This can fix TTC.

Otherwise, from brief look there is nothing except high system load.

Hope that helps.

3

This could be due to the serial corruption bug present in the usbserial firmware of the Einsy’s 32u2. The log shows retransmits creeping up over time.

The link here provides updated firmware and instructions for flashing.