UDEV Setup

The CC hotend, for some reason boots up a generic ACM device:

Extract from dmesg 

[   89.084013] usb 1-1.2: USB disconnect, device number 3
[   89.313505] usb 1-1.2: new full-speed USB device number 4 using xhci_hcd
[   89.423364] usb 1-1.2: New USB device found, idVendor=1d50, idProduct=614e, bcdDevice= 2.00
[   89.423379] usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[   89.423383] usb 1-1.2: Product: STM32 Virtual ComPort
[   89.423386] usb 1-1.2: Manufacturer: ShenZhenCBD
[   89.423390] usb 1-1.2: SerialNumber: 3664356E3233

But after ~10-20 second of idle, it shuts down and resets as an STM32 Klipper Serial Device:

Extract from dmesg 

[  126.721014] usb 1-1.2: USB disconnect, device number 4
[  126.948951] usb 1-1.2: new full-speed USB device number 5 using xhci_hcd
[  127.060969] usb 1-1.2: New USB device found, idVendor=1d50, idProduct=614e, bcdDevice= 1.00
[  127.060984] usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[  127.060988] usb 1-1.2: Product: stm32f401xc
[  127.060992] usb 1-1.2: Manufacturer: Klipper
[  127.060995] usb 1-1.2: SerialNumber: 39002C000B51333235353836
[  127.064802] cdc_acm 1-1.2:1.0: ttyACM1: USB ACM device

During this process, first it's assinged the device id ttyACM0 (when no other tty devices are present) but after reset, it shows up as ttyACM1.

To have a constant simlink to the device, we can set up an udev rule for the device using the vendor and device id.

  1. Go to /etc/udev/rules.d
  2. Open a text editor with a new file with .rules extension, do not edit the existing file, e.g.: sudo nano cc-hotend-device.rules
  3. Paste KERNEL=="ttyACM[0-9]*", SUBSYSTEM=="tty", ATTRS{idVendor}=="1d50", ATTRS{idProduct}=="614e", SYMLINK="ttyHotend"

To figure out your specific vendor id and product id, disconnect and connect the hotend from the Host, then type dmesg. Refer to the above log extracts to see what is expected.