[sane-devel] Genesys driver for CanoScan LiDE 90

[Pierre Willenbrock]

Hi Volker,

Volker Grabsch schrieb:
> Dear Sane Developers,
> 
> I just started to analyze my scanner "CanoScan LiDE 90".
> 
> I'm using the current sane-backends tools (CVS version) with the
> experimental genesys drivers (CVS version).
> 
> According to sane-find-scanner it contains a GL842 chipset.
> However, the genesys driver have only support for GL841. So I
> decided to try this driver and extended the genesys driver.

Iirc, the gl841 and gl842 use the same register set.

> My changes are very primitive (see the attached patch). I just
> copied the entries from lide-50 and adjusted some values. But
> at least it makes the scanner move.
> 
> There are some strange delays, but after c. 20 seconds the scanner
> starts. It is able to tun a preview and a real scan, at least the
> scanner's motor is moving as if it would scan. However, it returns
> always just a black image instead of the paper I'm scanning.

The delays are caused by failing calibration of the optical parameters,
because the gl842 chip only receives black data from the analog
frontend. You need to find the correct parameters for the frontend and
the correct gpio-setup, especially for the half-resolution mode of the
sensor.

To get this information, you need to get an usb log from the windows
driver of a low resolution(for example preview) and full resolution
scan. The scanned area can be very small. To take the log, i recommend
using usbsnoop:

 http://benoit.papillault.free.fr/usbsnoop/

For some more information see my previous message about the CanoScan
LiDE 90:

http://lists.alioth.debian.org/pipermail/sane-devel/2007-September/019945.html

> Is there any genesys hacker or any genesys documentation
> about how to add support for a new scanner to that driver?
> Is the experimental genesys driver still in active development?

Hope that helps,
  Pierre