Unable to enumerate USB device - unknown device: how to find out device that odes not show in lsusb?

Question

I have a hardware product which sends a signal to an LCD display. The hardware box (unknown chip set) has an USB-A outlet and connects to a USB-B outlet on an LCD-display. The LCD display shows different values in a one second interval. I would need to read the values from the Hardware box with whatever Linux-based machine. I have tried a Raspberry that connects per USB to the hardware box. However, when I try to enumerate usb devices via lsusb the device does not show up. It just shows my keyboard and mouse.

When I look at the dmesg outpout, I get the following:

[    2.411997] usb 1-1.3: new low-speed USB device number 6 using dwc_otg
[    2.511983] usb 1-1.3: device descriptor read/64, error -32
[    2.731995] usb 1-1.3: device descriptor read/64, error -32
[    3.192015] usb 1-1.3: new low-speed USB device number 8 using dwc_otg
[    3.292089] usb 1-1.3: device descriptor read/64, error -32
[    3.512305] usb 1-1.3: device descriptor read/64, error -32
[    4.292059] usb 1-1.3: new low-speed USB device number 9 using dwc_otg
[    4.732030] usb 1-1.3: device not accepting address 9, error -32
[    4.832062] usb 1-1.3: new low-speed USB device number 10 using dwc_otg
[    5.272043] usb 1-1.3: device not accepting address 10, error -32
[    5.272238] usb 1-1-port3: unable to enumerate USB device

I tried pyserial, but does not know which device to read from. I do not get the idVendor and idProduct, I do not know whether there is a driver that I can update or something.

I have been going through a lot of documentation, set the speed of the usb-driver to 1 (via dwc_otg.speed=1 that did not help either). I tried all the things here:https://www.raspberrypi.org/documentation/configuration/cmdline-txt.md But nothing helped. I have two questions:

1. What else can I potentially do to debug the usb connection?
2. How can I identify a USB device that is not being listed by lsusb and gives an error in dmesg?

This is quite important for my research so any help is much appreciated.

Solution

The error message you're seeing is from a low-level USB failure, the basic USB protocol hasn't been completed — so Linux probably doesn't even know the idVendor/idProduct yet. That's also why lsusb isn't showing it, it hasn't really connected yet.

The first odd thing here is that it has a USB A port, normally that's on the computer/"host" side (and B is on the device/"gadget"). So it sounds like the way its used with the display is the "hardware product" functions like a computer, and is controlling the display. It sounds like you're trying to connect two USB A ports together, that isn't supposed to work (or be physically possible).

If you want your Pi to work like the display, you likely need to do a lot of work to make it present itself as a display. That's called USB gadget mode. Writing the programs to make that happen would be something to ask about on Stack Overflow; it's definitely software development.

If your hardware device is supposed to connect to a computer as well, then it may implement both modes (often called USB On-The-Go). If that's the case, it should be able to talk to the Pi, but that's not working. First debugging step would be to see if it works on a PC — even a Windows one. If it doesn't, then I doubt there is much to do other than contact the vendor. If it does, it's possible your Pi isn't able to supply it enough power; make sure you're using a good USB power supply with the Pi.

BTW: Another thing that comes to mind to investigate how the two devices communicate is to plug the display into your Pi or computer. The one you can use a normal USB cable with; see what type of device it is. If it shows up as a monitor (and not say a serial port)... good luck!

Comments

[Cactus]

Hello derobert, thank you, your answer is very helpful. Yes, it comes down to connecting two USB A ports. I thought if the signal sent from the hardware device is being read by a display, I could have a chance to also read it from the Raspberry. I have already contacted the vendor, however, they are very unresponsive. If the hardware device really controls the display, do you have any pointers/resources where I could read how to put the Raspberry in USB gadget mode? I would not know how to start, since I do not even know which signal is coming from the hardware device. Thanks!

[Cactus]

Do you think a USB to ttl converter such as this one could help: amazon.com/ADAFRUIT-Industries-954-Serial-Raspberry/dp/…

[derobert]

@Cactus Not all Raspberry Pi support gadget mode (see raspberrypi.stackexchange.com/questions/71613/… which also has some links on how to do it). USB a simple protocol like you might be used to from, e.g., RS-232 serial ports. You've got a potentially large amount of work ahead of you...

[derobert]

@Cactus Also, I thought of another way to investigate what the hardware is doing, I added it to the bottom of an answer.