ch341-uart - ttyUSBx disconnecting???

[Jeffrey Ross]

I'm trying to connect an Arduino to my system (Fedora 38 - 
6.5.12-200.fc38.x86_64) that uses a ch341 serial uart.

I've been searching around and found issues on other distributions and 
the "brltty" application, since I don't need braille I removed the 
application but the problem remains.  I have also found a different 
driver called "CH341SER"  so I tried unloading the existing ch341 module 
and installing CH341SER (module shows up as ch34x) but other than 
tainting the kernel it made no different so I unloaded the module.

I have been unable find anything specific to Fedora or anything 
relatively new but it appears to be a common issue across multiple 
distributions.

Any pointers would be appreciated, see below for dmesg output.

Thanks,
Jeff

[  268.820420] usb 1-9.3.7: new full-speed USB device number 50 using 
xhci_hcd
[  268.897931] usb 1-9.3.7: New USB device found, idVendor=1a86, 
idProduct=7523, bcdDevice=81.34
[  268.897947] usb 1-9.3.7: New USB device strings: Mfr=0, Product=2, 
SerialNumber=0
[  268.897953] usb 1-9.3.7: Product: USB Serial
[  268.907342] ch341 1-9.3.7:1.0: ch341-uart converter detected
[  268.908444] usb 1-9.3.7: ch341-uart converter now attached to ttyUSB0
[  272.084557] usb 1-9.3.7: USB disconnect, device number 50
[  272.084964] ch341-uart ttyUSB0: ch341-uart converter now disconnected 
from ttyUSB0
[  272.085012] ch341 1-9.3.7:1.0: device disconnected
[  274.196380] usb 1-9.3.7: new full-speed USB device number 51 using 
xhci_hcd
[  274.273474] usb 1-9.3.7: New USB device found, idVendor=1a86, 
idProduct=7523, bcdDevice=81.34
[  274.273489] usb 1-9.3.7: New USB device strings: Mfr=0, Product=2, 
SerialNumber=0
[  274.273495] usb 1-9.3.7: Product: USB Serial
[  274.282837] ch341 1-9.3.7:1.0: ch341-uart converter detected
[  274.283898] usb 1-9.3.7: ch341-uart converter now attached to ttyUSB0
[  277.716513] usb 1-9.3.7: USB disconnect, device number 51
[  277.716910] ch341-uart ttyUSB0: ch341-uart converter now disconnected 
from ttyUSB0
[  277.716956] ch341 1-9.3.7:1.0: device disconnected

[Steve Underwood]

Hi Jeffrey,

I have a CH341 UART connected to this machine (Fedora 37 x86_64). Its 
stable, and has never caused me any real problems. However, my log looks 
slightly different. I get this:

Nov 29 13:43:34 haswell kernel: usb 1-4: new full-speed USB device 
number 12 using xhci_hcd
Nov 29 13:43:34 haswell kernel: usb 1-4: New USB device found, 
idVendor=1a86, idProduct=7523, bcdDevice= 2.64
Nov 29 13:43:34 haswell kernel: usb 1-4: New USB device strings: Mfr=0, 
Product=2, SerialNumber=0
Nov 29 13:43:34 haswell kernel: usb 1-4: Product: USB Serial
Nov 29 13:43:34 haswell kernel: ch341 1-4:1.0: ch341-uart converter detected
Nov 29 13:43:34 haswell kernel: usb 1-4: ch341-uart converter now 
attached to ttyUSB0

The bcdDevice field is different. That sounds like a big difference in 
revision numbers. Maybe we have different devices from the CH341 family. 
Maybe there is some compatibility issue there. Maybe you just have a 
dirty USB connector, or some other bad connection problem.

Steve

On 29/11/2023 02:55, Jeffrey Ross via users wrote:
> I'm trying to connect an Arduino to my system (Fedora 38 - 
> 6.5.12-200.fc38.x86_64) that uses a ch341 serial uart.
>
> I've been searching around and found issues on other distributions and 
> the "brltty" application, since I don't need braille I removed the 
> application but the problem remains.  I have also found a different 
> driver called "CH341SER"  so I tried unloading the existing ch341 
> module and installing CH341SER (module shows up as ch34x) but other 
> than tainting the kernel it made no different so I unloaded the module.
>
> I have been unable find anything specific to Fedora or anything 
> relatively new but it appears to be a common issue across multiple 
> distributions.
>
> Any pointers would be appreciated, see below for dmesg output.
>
> Thanks,
> Jeff
>
> [  268.820420] usb 1-9.3.7: new full-speed USB device number 50 using 
> xhci_hcd
> [  268.897931] usb 1-9.3.7: New USB device found, idVendor=1a86, 
> idProduct=7523, bcdDevice=81.34
> [  268.897947] usb 1-9.3.7: New USB device strings: Mfr=0, Product=2, 
> SerialNumber=0
> [  268.897953] usb 1-9.3.7: Product: USB Serial
> [  268.907342] ch341 1-9.3.7:1.0: ch341-uart converter detected
> [  268.908444] usb 1-9.3.7: ch341-uart converter now attached to ttyUSB0
> [  272.084557] usb 1-9.3.7: USB disconnect, device number 50
> [  272.084964] ch341-uart ttyUSB0: ch341-uart converter now 
> disconnected from ttyUSB0
> [  272.085012] ch341 1-9.3.7:1.0: device disconnected
> [  274.196380] usb 1-9.3.7: new full-speed USB device number 51 using 
> xhci_hcd
> [  274.273474] usb 1-9.3.7: New USB device found, idVendor=1a86, 
> idProduct=7523, bcdDevice=81.34
> [  274.273489] usb 1-9.3.7: New USB device strings: Mfr=0, Product=2, 
> SerialNumber=0
> [  274.273495] usb 1-9.3.7: Product: USB Serial
> [  274.282837] ch341 1-9.3.7:1.0: ch341-uart converter detected
> [  274.283898] usb 1-9.3.7: ch341-uart converter now attached to ttyUSB0
> [  277.716513] usb 1-9.3.7: USB disconnect, device number 51
> [  277.716910] ch341-uart ttyUSB0: ch341-uart converter now 
> disconnected from ttyUSB0
> [  277.716956] ch341 1-9.3.7:1.0: device disconnected

[Jeffrey Ross]

I should have added, I tried several USB cables and the device works 
without an issue on a Windows 11 system.

On 11/29/23 8:50 AM, Steve Underwood wrote:
> Hi Jeffrey,
>
> I have a CH341 UART connected to this machine (Fedora 37 x86_64). Its 
> stable, and has never caused me any real problems. However, my log 
> looks slightly different. I get this:
>
> Nov 29 13:43:34 haswell kernel: usb 1-4: new full-speed USB device 
> number 12 using xhci_hcd
> Nov 29 13:43:34 haswell kernel: usb 1-4: New USB device found, 
> idVendor=1a86, idProduct=7523, bcdDevice= 2.64
> Nov 29 13:43:34 haswell kernel: usb 1-4: New USB device strings: 
> Mfr=0, Product=2, SerialNumber=0
> Nov 29 13:43:34 haswell kernel: usb 1-4: Product: USB Serial
> Nov 29 13:43:34 haswell kernel: ch341 1-4:1.0: ch341-uart converter 
> detected
> Nov 29 13:43:34 haswell kernel: usb 1-4: ch341-uart converter now 
> attached to ttyUSB0
>
> The bcdDevice field is different. That sounds like a big difference in 
> revision numbers. Maybe we have different devices from the CH341 
> family. Maybe there is some compatibility issue there. Maybe you just 
> have a dirty USB connector, or some other bad connection problem.
>
> Steve
>
> On 29/11/2023 02:55, Jeffrey Ross via users wrote:
> > I'm trying to connect an Arduino to my system (Fedora 38 - 
> > 6.5.12-200.fc38.x86_64) that uses a ch341 serial uart.
> >
> > I've been searching around and found issues on other distributions 
> > and the "brltty" application, since I don't need braille I removed 
> > the application but the problem remains.  I have also found a 
> > different driver called "CH341SER"  so I tried unloading the existing 
> > ch341 module and installing CH341SER (module shows up as ch34x) but 
> > other than tainting the kernel it made no different so I unloaded the 
> > module.
> >
> > I have been unable find anything specific to Fedora or anything 
> > relatively new but it appears to be a common issue across multiple 
> > distributions.
> >
> > Any pointers would be appreciated, see below for dmesg output.
> >
> > Thanks,
> > Jeff
> >
> > [  268.820420] usb 1-9.3.7: new full-speed USB device number 50 using 
> > xhci_hcd
> > [  268.897931] usb 1-9.3.7: New USB device found, idVendor=1a86, 
> > idProduct=7523, bcdDevice=81.34
> > [  268.897947] usb 1-9.3.7: New USB device strings: Mfr=0, Product=2, 
> > SerialNumber=0
> > [  268.897953] usb 1-9.3.7: Product: USB Serial
> > [  268.907342] ch341 1-9.3.7:1.0: ch341-uart converter detected
> > [  268.908444] usb 1-9.3.7: ch341-uart converter now attached to ttyUSB0
> > [  272.084557] usb 1-9.3.7: USB disconnect, device number 50
> > [  272.084964] ch341-uart ttyUSB0: ch341-uart converter now 
> > disconnected from ttyUSB0
> > [  272.085012] ch341 1-9.3.7:1.0: device disconnected
> > [  274.196380] usb 1-9.3.7: new full-speed USB device number 51 using 
> > xhci_hcd
> > [  274.273474] usb 1-9.3.7: New USB device found, idVendor=1a86, 
> > idProduct=7523, bcdDevice=81.34
> > [  274.273489] usb 1-9.3.7: New USB device strings: Mfr=0, Product=2, 
> > SerialNumber=0
> > [  274.273495] usb 1-9.3.7: Product: USB Serial
> > [  274.282837] ch341 1-9.3.7:1.0: ch341-uart converter detected
> > [  274.283898] usb 1-9.3.7: ch341-uart converter now attached to ttyUSB0
> > [  277.716513] usb 1-9.3.7: USB disconnect, device number 51
> > [  277.716910] ch341-uart ttyUSB0: ch341-uart converter now 
> > disconnected from ttyUSB0
> > [  277.716956] ch341 1-9.3.7:1.0: device disconnected
>
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