Using Linux (LMint 20) what can I do to to trouble shoot ttyACM connection.

[GreenGuy]

LMint 20 (based on Ubuntu 20) no ttyACM connection show up after the DK2 board is loaded with the Flash firmware using STM32 Programmer. The board boots as the wiki shows but no ttyACM devices show up to use with minicom.

I am stuck.

[Ozone]

Had your user benn added to the tty/dialout group ?

I mostly used moserial as terminal application, although not yet with the very latest Mint version.

[GreenGuy]

I was not part of the tty or dialout groups. I added those to my user but it did not make a difference. I do note that when the USB connection is made to the OTG port STM32_Programmer can use it and a new device shows up in the lsusb as:

Bus 001 Device 003: ID 1d6b:0104 Linux Foundation Multifunction Composite Gadget

Since the group changes I have also tried Sudo udevadm control --reload, Logout and login, and a restart without success.

I can plug in a STlinkV2 usb pod and STM32_Programmer sees it. But when I plug in the STLink usb from the DK2 board to the PC STM32_Programmer does not see it.

[GreenGuy]

Solved!

I connected the DK2 with the USB (STLINK) cable to a Windows PC and the Com port did not show up in the Device manager. Started swapping other Type A to micro cables until it worked (STLINK Com port appeared). Moved it back over to the Linux PC and voila, the ttyACM0 appeared.

Solution = use known good cables for data transfer.

[GreenGuy]

And yes I had to have the proper groups selected and the Linux installs for STM32 tools on linux do not set these groups for the user. Also the instructions to do this are also missing from the installation documentation and the Wiki.

[Ozone]

It seems there is not much Unix/Linux knowledge present with ST, at least within their toolchain and MCU teams.

Fortunately, there are plenty of generic resources for Linux-related help.