Ender 3 V2 MCU connection issue

Basic Information:

Printer Model: Ender 3 V2
MCU / Printerboard: 4.2.2
Host / SBC: OctoKlipper
klippy.log (41.1 KB)

mcu ‘mcu’: Unable to connect

-Disconnect LCD Ribbon from Mobo
-Taped 5V USBA from Pi to printer to prevent power related issues
-Replaced cable
-Used different USB port(s)
-Reflashed (used different name)
-Reinstalled Octoprint (OctoKlipper) up to date
-Set Octoprint serial connection settings Baudrate - 115200
-Config file with right MCU and included Baud: 115200

Firmware Config:
[*] Enable extra low-level configuration options
STMicroelectronics STM32
28KiB bootloader
(115200) Baud Rate for serial port

dmesg USB infomation
[ +0.148028] usb 1-1: New USB device found, idVendor=2109, idProduct=3431, bcdD evice= 4.21
[ +0.000061] usb 1-1: New USB device strings: Mfr=0, Product=1, SerialNumber=0
[ +0.000028] usb 1-1: Product: USB2.0 Hub
[ +0.002000] hub 1-1:1.0: USB hub found
[ +0.000300] hub 1-1:1.0: 4 ports detected
[ +0.191031] systemd[1]: System time before build time, advancing clock.
[ +0.103990] usb 1-1.1: new full-speed USB device number 3 using xhci_hcd
[ +0.091013] NET: Registered PF_INET6 protocol family
[ +0.002093] Segment Routing with IPv6
[ +0.000063] In-situ OAM (IOAM) with IPv6
[ +0.014982] usb 1-1.1: New USB device found, idVendor=1a86, idProduct=7523, bc dDevice= 2.64
[ +0.000062] usb 1-1.1: New USB device strings: Mfr=0, Product=2, SerialNumber= 0
[ +0.000030] usb 1-1.1: Product: USB Serial

Any help would be great!!!

First off, you’re tracking a weird Git repository for Klipper.
I think you’re pulling Kevin’s version which I think is his test version.

Git version: 'f7567a0'
Branch: master
Remote: origin
Tracked URL: https://github.com/KevinOConnor/klipper.git

It should be like this…

Git version: 'v0.12.0-143-g01c7befa'
Branch: master
Remote: origin
Tracked URL: https://github.com/Klipper3d/klipper

Second, The recommended baud rate for Klipper is 250000 and stated in the FAQs


Third - Are you using serial or USB? It seems like you have a weird mix of both.

Third, your serial setup is just a symbolic link to one of the USB ports.
They can do wonky things sometimes.


ls -l /dev/serial/by-id/usb-1a86_USB_Serial-if00-port0

You’ll get an output like

lrwxrwxrwx 1 root root 13 May 15 12:34 /dev/serial/by-id/usb-1a86_USB_Serial-if00-port0 -> ../../ttyUSB0

Whatever is at the end of that, you can change your serial: to in your [mcu] to temporarily see if that works. In other words…

serial = /dev/ttyUSB0

In general it’s better to use the /dev/serial/by-id/… path but I’ve seen where people have had issues with that.

Try those things first and come back

Got rid of OctoKlipper and went for mainsail.

Git version: ‘v0.12.0-192-gb7f7b8a3’
Branch: master
Remote: origin
Tracked URL: GitHub - Klipper3d/klipper: Klipper is a 3d-printer firmware

I lowered the Baud to 115200. Supposedly with the 4.2.2 board and this issue people have had success with a lower baudrate. Tried both to no avail

And no luck with Serial = /dev/ttyUSB0

klippy.log (145.9 KB)
New Klippy for new build

Baud is defaulted back to 250000
Everything is defaulted to this guide: How to Install Klipper on the Ender 3 (With Mainsail OS) | Obico Knowledge Base
with the exception of your above mentioned suggestion serial = / dev/ttyUSB0