RPi 4 (emteria.OS v11.2.0) - USB-RS232 driver problem

kiwi

Hello,

We test sending USB-RS232 commands using Aten UC 232A. And we came across a problem where RPi4 does not register Aten USB-RS232 as ttyUSB0, but as xhci_hcd. On RPi3 (emteriaOS 1.3.0) everything works properly, Aten registers as ttyUSB0 (pl2303) and commands can be sent to it.

We want to ask why the RPi4 USB-RS232 converter registers badly and not like ttyUSB0?

Regards,

F. Slezák

kiwi

Hi,

I would like to remind my question about RS232 on rpi4.

Jan_Kehren

Hey @kiwi,
sorry for the late reply.
A lot of things changed from RPi3 to RPi4 eg. USB drivers. xhci_hcd is the USB3 driver.
RPi4 has 2xUSB 3 and 2xUSB 2 ports have you tried a different port?
Another option to try would be adding dtoverlay=dwc2,dr_mode=host to your config.txt to change the USB driver.
Another question from my side would be why are you using a USB to RS232 converter isn't the built-in UART on PIN14&15 sufficient for your use case?

Regards,
Jan

kiwi

Hi,
thanks for the reply, the ports we tried and the behavior is the same.

Where exactly should config.txt be located? In the /boot folder?

Regards,

Filip

kiwi

Hi,
so i found it in the /boot folder, but it's set up correctly. Can you think of another solution?

smieschek

@kiwi
The dtoverlay=dwc2,dr_mode=host you have in the config.txt is only applied when running on a compute module (cm4). If you are running a normal RPi4 you need to put it under the [all] guard.
Meaning: try to copy line 3 to somewhere after line 6.

linusekstrom

@kiwi
Have you been able to solve this in any way? We have the exact same problem with our serial device which gets registered as xhci_hcd, and no ttyUSB* device is added when plugging in the device. I have tried all of the USB ports, getting the same result.

We have tried to move the dtoverlay=dwc2,dr_mode=host line to be included under the [all] line as @smieschek suggested.

Everything is working perfect when running a RBPi3 running emteria.OS v7.3.0 but not with our RBPi4 running emteria.OS v11.3.0.

Does anyone have an update on this?

smieschek

@linusekstrom Another customer had a similar issue and we were able to fix it. Can you try nightly v11.6.10 for RPi4 and see if your device gets listed?