STLinkv2-1 under Linux and ttyACM

[Félix TREFOU]

Hi,

Everyone who uses ST Link under ubuntu knows the waiting time to use the ttyACM to display traces.

This time is due to the ModemManager trying to send commands for a few tens of seconds.

When I try to disable this service or add the STLink to the BLACKLIST, the STLink continuously resets the STM32 for some reason.

An idea of ​​what could cause this behavior?

[Pavel A.]

From the Modem Manager docum [1] you can configure this via udev rules.

[1] https://www.freedesktop.org/software/ModemManager/api/latest/ref-overview-modem-detection.html#id-1.2.3.2

[Félix TREFOU]

Yes that's what i've done, and it actually worked.

But when modemManager don't deal with our STLink, STLink reset continuously the STM32. (As if it is receiving USB commands for reset constantly )

[Félix TREFOU]

What i'm saying is that MM seems not to be responsible of that.

[Pavel A.]

Maybe the USB host tries to autosuspend the st-link. Is your machine a laptop? See here :

https://askubuntu.com/questions/185274/how-can-i-disable-usb-autosuspend-for-a-specific-device

-- pa

[Félix TREFOU]

Thanks for your answer.

I completely stopped tlp.service on my ubuntu and the problem is still there :\

[fronders]

For me, the only solution that worked was to remove the modemmanager package. Here's more description on that: https://electronics.stackexchange.com/questions/288187/is-it-possible-to-get-st-links-virtual-com-port-working-without-launching-any-p