I am new to Linux. I have been programming for over 15 years, mostly C/C++ and assembly.

I have been assigned the task of writing a User Space Device Driver for a USB device. The device is a barcode scanner which the system sees as a Keyboard.

I am trying to figure out how to know when a new device is plugged into the computer so that the device driver can be started and receive information from the scanner.

I am trying to use usbfs and libusb in writing this driver.

If I am wrong or you can point me in the correct path I would be very appreciative.

John V.

An interesting question. It doesn't seem to me that a "device driver" in the usual (kernel) sense will be needed. This will be an interface library to be used by the application-program ... it seems of little use to me to try to treat this device as "a separate device-type" nor to mount it globally to the system. For that reason, it seems irrelevant to "detect when the device is plugged-in."

The interface-library might poll the various USB devices and see which one identifies itself as a scanner... "/proc" or "/sys" or "/dev" and so-forth can tell you that (see lsusb and its man-page). Then open that device and make it very easy for the application to do what it needs to do with the device.

But it's just a user library, and I'll daresay that a suitable one probably already exists. . .

You opinions is right. The usb driver libraries have been wrote, you can download them, in china I have tried to do this, and we have a relerant paper for this problem now, but it is in Chinese, sorry,
Then maybe you can find another documentation about your opinions now,

I think it is very useful, but it is not efficent, ........of cource you can port your usb drivers to other OS, provided you have completed your projetcts,,,,,

Good luck!

I want to thank you for your help.

The barcode scanner software that I am working on is for an embedded system and there may be more than one connected to the system at any one time. I thought of polling and placed that before the management but they said that it was unexceptable. The barcode scanner currently shows up as a keyboard usb device.

Once again, I thank you for your help and suggestions.

John V.

As you'll see, an application-library can scan the USB devices to find out just what kind of device they are, e.g. as lsusb does. So, when asked to open a scanner, it can look to find one that isn't already in-use. And so on.