Who can help me get klipper working on my ender 3v2 :(

[Molier]

Ender 3v2 (4.2.2 Board) - Klipper Serial Connection Failures Despite Correct Setup

Hardware:

• Ender 3v2 (4.2.2 board)
• Raspberry Pi 3 (64-bit Lite OS, headless)
• OctoPrint partially connects, Klipper fails

Attempts:

1. Firmware:

   • Built with STM32F103, 28KiB bootloader, 8MHz crystal, USART1 PA10/PA9.
   • Re-flashed via SD card (FAT32/4096 block) with unique filenames (e.g., firmware-2024.bin).
   • Successfully flashed Marlin previously (confirms SD card works).

2. Config:

   • printer.cfg based on the one from github
   • Tested all diferent sorts of baud rates

3. Troubleshooting:

   • Swapped USB cables/ports (tested USB 2.0/3.0).
   • Verified permissions (dialout group, ls -l /dev/serial/by-id/*).
   • Checked lsusb (STM32 detected).
   • Manual serial test (cat /dev/serial/by-id/...) shows garbage output.
   • Power cycled printer/Pi, reseated cables.

Symptoms:

• OctoPrint connects but Klipper logs mcu 'mcu': Serial connection closed / Timeout on connect.

Suspicions:

• GD32F303 chip (not STM32F103) on 4.2.2 board?
• Faulty 8MHz crystal or USB port?
• Hidden config mismatch?

Request:

• Has anyone resolved this on a 4.2.2 board with GD32F303?
• Are there known Pi 3/Klipper quirks for Ender 3v2?
• Debug steps I’ve missed?

Logs/Configs:

• make menu config:
  

  

• Full klippy.log:

Traceback (most recent call last):
  File "/home/oscar/klipper/klippy/serialhdl.py", line 68, in _get_identify_data
    params = self.send_with_response(msg, 'identify_response')
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/oscar/klipper/klippy/serialhdl.py", line 262, in send_with_response
    return src.get_response([cmd], self.default_cmd_queue)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/oscar/klipper/klippy/serialhdl.py", line 319, in get_response
    self.serial.raw_send_wait_ack(cmds[-1], minclock, reqclock,
  File "/home/oscar/klipper/klippy/serialhdl.py", line 254, in raw_send_wait_ack
    self._error("Serial connection closed")
  File "/home/oscar/klipper/klippy/serialhdl.py", line 61, in _error
    raise error(self.warn_prefix + (msg % params))
serialhdl.error: mcu 'mcu': Serial connection closed

Ive read a lot of similar topics but none had any help that fixed things for me: Reflashed klipper (ender v3 se) and now getting mcu error - #11 by hcet14
Installing Klipper on Ender 3 - 4.2.2 Board and GD32F303 Chip

[EddyMI3D]

Hello @Molier !

@Molier

• Full klippy.log:

Traceback (most recent call last):
  File "/home/oscar/klipper/klippy/serialhdl.py", line 68, in _get_identify_data
    params = self.send_with_response(msg, 'identify_response')
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/oscar/klipper/klippy/serialhdl.py", line 262, in send_with_response
    return src.get_response([cmd], self.default_cmd_queue)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/oscar/klipper/klippy/serialhdl.py", line 319, in get_response
    self.serial.raw_send_wait_ack(cmds[-1], minclock, reqclock,
  File "/home/oscar/klipper/klippy/serialhdl.py", line 254, in raw_send_wait_ack
    self._error("Serial connection closed")
  File "/home/oscar/klipper/klippy/serialhdl.py", line 61, in _error
    raise error(self.warn_prefix + (msg % params))
serialhdl.error: mcu 'mcu': Serial connection closed

@Molier

OctoPrint connects but Klipper logs mcu 'mcu': Serial connection closed / Timeout on connect.

Please upload the complete klippy.log as a file here.

[Molier]

klippy.log (836.9 KB)

it is full of previous attempts as well

[Molier]

in the end a complete redo magically fixed it. stock settings in the printer.cfg, from klipper/config/printer-creality-ender3-v2-2020.cfg at master · Klipper3d/klipper · GitHub . a fresh .bin firmware with a unique filename on a fat32, 4096 sd card. with the same settings as in the image

and it suddenly worked.

[JamesH]

always Magic