Camera problems with Linux

[David Griffiths]

I built my PNP machine and tested it in my office using Win 10. I now want to move it to the workshop with a dedicated PC. I decided to try Linux, which is way out of my comfort zone!

I have two identical ELP HD USB cameras for UP and DOWN and a cheapy webcam for what I call a scenic view (handy when working with a remote colleague).

I have installed Linux Mint 20.3 Cinnamon.

I can view each camera individually (using GUVCView) but OpenPNP can only see one of the cameras.

LSUSB shows all cameras on Bus 1. My first assumption was that the bus related to the host controller that each port was physically attached to, but I have seen a physical port change to bus 2 when a different device was plugged in.

The PC is a circa 2009 machine with an ASUS mobo but I have also tried one with a Gigabyte Mobo of similar vintage with the same results.

My guess is that OpenPNP wants to see the cameras on different busses (possibly because the two ELP cameras have the same ID and serial number (zero).)

Am I looking at a mobo hardware/design issue or a Linux/driver issue or an OpenPNP/Java issue?

Would it help if I bought a PCI USB card?

Any guidance is welcome.

DG

[mark maker]

If they are HD, they should work, even if connected to the same root USB hub. But if they are Full HD, they will not work if connected to the same root USB hub, the band-width is not enough.

https://github.com/openpnp/openpnp/wiki/USB-Camera-Troubleshooting-FAQ#why-does-mjpeg-still-not-help-for-some-cameras

_Mark

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[David Griffiths]

Hi Mark,

They are Full HD 1920x1080.  So the question is how do I get them to connect to different root hubs?  Or am I wrong to be reading the 'Bus' number that LSUSB shows me?

DMESG seems to be showing similar information.  eg USB1-2 which I read as Bus 1 Device 2 etc.

DG

[mark maker]

I don't know enough of Linux to really help there. You just need to make sure to get two different USB root hubs, i.e. plug in the two cameras directly to the PC (no hub), and on plugs that are not internally sharing a hub on the mobo. If I were you, I would just try different combinations of plugs on the PC.

_Mark

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[Ian Arkver]

lsusb -t

will show the tree structure and easily determine which root hubs are being used.

[David Griffiths]

Ah, thanks Ian, I will try that.

DG

[David Griffiths]

Update...  I have resolved the problem. I tried four old machines without much joy, so I bit the bullet and acquired a much more recent machine with Win 10 on it and I can now see both UP & DOWN cameras at the same time. I haven't tried the scenic camera yet.

I think the USB architecture on the old machines was the problem.