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Enable ACM for serial tty

Posted: 2026-02-19 8:15
by scanhead
Greetings,

I need serial communication over USB but i cant get ACM working? i tried to follow the instructions for pico viewtopic.php?t=1157 but i'm not having any luck? Ethernet and ADB work, but just not serial, no tty. Im just using the SDK.

Thanks for your time :)

usb_f_acm (& usb_f_hid)

Posted: 2026-02-20 15:05
by jeff
Hi,
I have a Luckfox-Lyra-Ultra-Poe-Kit. I'm trying to access it from PC via USB (OTG) as serial port.
I'm currently using Ubuntu-Image. Unfortunately it seems to be missing the usb_f_acm support, as well as the usb_f_hid.
The SBC has USB-OTG (even two of those) - how can I configure it to provide a serial port to the PC?
Thanks
Jeff

Re: Enable ACM for serial tty

Posted: 2026-02-24 3:50
by Crocodile
To activate the ACM function, you need to enable CONFIG_USB_CONFIGFS_ACM in the kernel source code. Re-compiling the kernel and the rootfs is necessary to support ACM.
If using Ubuntu-Image, you need to synchronize and move all the .ko files in the $SDK/output/rootfs/target/usr/lib/modules/6.1.99/kernel/drivers/usb/gadget/function directory generated by compiling the buildroot rootfs to the Ubuntu rootfs.

Re: Enable ACM for serial tty

Posted: 2026-02-27 7:07
by scanhead
So, has to be in kernel, cannot be a module. will try that.

Re: Enable ACM for serial tty

Posted: 2026-02-28 0:20
by scanhead
does this look right?

root@luckfox:/etc/profile.d# cat /var/log/usbdevice.log
[1970-01-01 00:00:12] usbdevice: Handling start request
[1970-01-01 00:00:12] usbdevice: Run stage: usb_prepare
Loading configs from /etc/.usb_config ...
[1970-01-01 00:00:13] usbdevice: Run stage: usb_init
[1970-01-01 00:00:13] usbdevice: Initializing
[1970-01-01 00:00:13] usbdevice: USB state: DISCONNECTED
[1970-01-01 00:00:13] usbdevice: Using USB UDC device: ff740000.usb
[1970-01-01 00:00:13] usbdevice: Run stage: usb_start
[1970-01-01 00:00:13] usbdevice: Starting functions: rndis acm=on adb
[1970-01-01 00:00:13] usbdevice: Preparing instance: rndis.0
[1970-01-01 00:00:13] usbdevice: Preparing instance: ON_INSTANCES:-acm=on.0
[1970-01-01 00:00:13] usbdevice: Failed to create instance: ON_INSTANCES:-acm=on.0
[1970-01-01 00:00:13] usbdevice: Preparing instance: ffs.adb
[1970-01-01 00:00:13] usbdevice: Run stage: adb_prepare
adbd I 01-01 00:00:14 820 848 usb.cpp:239] initializing functionfs
adbd I 01-01 00:00:14 820 848 usb.cpp:261] opening control endpoint /dev/usb-ffs/adb/ep0
[1970-01-01 00:00:14] usbdevice: Starting instance: rndis.0
[1970-01-01 00:00:14] usbdevice: Starting instance: ffs.adb
[1970-01-01 00:00:14] usbdevice: Done start request