Re: [Libusb-win32-devel] problem with sane and libusb-win32

[Stephan M. <ste...@we...>]

>
> Hi all,
> I am relatively new to libusb-win32 and I am testing the snapscan driver
> for sane on cygwin.
>
> I use WinXP Professional + CygWin 1.5.10 + sane 1.0.14 + libusb-snapshot-20040816
> The hardware is an USB scanner EPSON Perfection 1670 Photo.
>
> I did installed the filter from the libusb-win32 snapshot since I already have
> the original driver from epson installed on that computer. If I try to
> install the device from libusb-win32, after changing the VID and PID in the .INF
> file, then the driver is correctly installed but it is ignored. This means that
> when I plug the USB cable then the EPSON driver is loaded instead of libusb-win32.
>

I think the reason for this behavior is that libusb's kernel driver is not 'digitally signed'
by Microsoft. If Windows has two drivers available for a device it will always load
the signed one (the Epson driver in this case) and ignore the unsigned driver.

To overcome this problem you could try to install libusb's device driver as follows:

- open the Device Manger
- select the Epson Scanner
- right-click->uninstall
- open the 'C:\WINNT\inf' folder and remove all oem*.inf and oem*.pnf files
- if this folder contains .inf and .pnf files related to your scanner driver delete them
- disconnect and reconnect the scanner
- when the 'Found new hardware' dialog appears, choose libusb's .inf file

> The problem is that scanning does not work. This arise before the scan
> start since libusb gives an error while downloading the gamma tables to
> the scanner.

It could be possible that sane somehow interferes with the epson driver, that
the epson driver already initialized the device, and that the device is already in
a state where it doesn't accept any configuration data (gamma tables).

So the best approach whould be to get rid of the Epson driver and use libusb's
device driver just for testing.


Stephan

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