[Wlug] Seeking help with a USB barcode scanner

[Jamie Guinan]

On Mon, 2 Apr 2007, Andy Stewart wrote:

> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> Tim Keller wrote:
> > This is what I would do.
> > 
> > 1. Install "lsusb".  It behaves much like lspci so you can what devices
> > are on your system.
> > 
> > When you do a "lsusb" it'll list what devices are hanging off of each
> > USB bus. Do a before and after so you can see the major/minor numbers.
> > 
> > 2. When you know the devices major and minor number you can write a
> > program using libusb that'll look for the device, open the device if it
> > exists,  take posession of it and then read data to and from it, hopefully.
> > http://libusb.sourceforge.net/doc/examples-code.html
> > 
> > Looking at that example, I don't think it would be too hard to whip up a
> > program to open the device and then loop until there's input and then
> > dump it on the screen.
> > 
> > Thanks,
> > Tim.
> 
> HI Tim,
> 
> Thanks for the tip about libusb.  I have lsusb installed, and I also
> have usbview.
> 
> I'm surprised that I can't find the proper thing to "cat" to see output
> from the barcode reader.  That would be the shell equivalent of what you
> propose.  If I could find that, I'd be in business.  I'm 99% certain
> that I'm looking in the right place.  Now, I wonder if it is possible
> that the barcode reader is defective.......hummmmm.
> 
> Once I find the right file to "cat", whipping up a program to grab the
> bytes and deal with them would be fairly trivial, I agree.
> 
> Thanks!
> 
> Andy

It might be that the device needs some initialization before it will
start returning data.  I wouldn't expect this for a HID device, but
since the event* nodes aren't showing anything, who knows...

In the kernel, it would be interesting to see what happens if you 
turn on DEBUG in hid-input.c, which currently contains,

#undef DEBUG
...
static void hidinput_configure_usage()
     ...
     goto ignore;  // lots of these gotos! -jamieg
     ...
ignore:
#ifdef DEBUG
	printk("IGNORED\n");
#endif

-Jamie