[sane-devel] Canan CanoScan 8400F backend driver

[John McGill]

The 8400f is reported to have a GL843 processor. Study the source code
of the genesys backend. You may be able to clone the settings of an
existing supported GL843 scanner.
https://help.ubuntu.com/community/CheckIfScannerIsClone

Stef Voltz maintains the genesys backend and may be able to help you.

Jack


On Mon, Aug 29, 2011 at 7:41 AM, Alejandro Imass <ait at p2ee.org> wrote:
> On Mon, Aug 29, 2011 at 5:01 AM, Chris Molanus <chrismolanus at hotmail.com> wrote:
>> Hi,
>> I would like to attempt to create backend support for the Canon CanoScan
>> 8400f Scanner.
>> I am finding it difficult to to find information on how to start as I have
>> never done this before.
>> I can program in C but have no experience in writing back end drivers.
>> Can anyone point me to some information are tell me a good place to start?
>> Chris
>> --
>
> There are already some Canon ADF drivers that work pretty well. The
> process is not that simple as there are a lot of details regarding
> mechanical movements, sensors and there is always the possibility of
> damage to the device while developing.
>
> The usual method is to snoop the comm between the OS and the scanner
> by using the officially supported driver in the supported OS, e.g. the
> Windoze driver. Is the interface is USB you can use the USB Snoop
> program and capture a sample scan of a black and white page and then a
> color one. Your test subjects should be large rectangles of color
> and/or black so it makes it easier to identify the image data block.
>
> It's a painstaking job but you need to figure out the protocol first.
> You will need background into many subjects of which C is probably the
> least of your worries. Before you talk to the scanner in Linux you
> need to understand about the USB subsystem, probably deal with libusb,
> udev and/or hal (a.k.a. hell ;-) ) and many other layers of software
> and options that Sane handles. Remember that Sane runs on many types
> us *nix set-ups so there are *many* options and paths to talk to the
> hw.
>
> I wanted to build a driver myself a few years ago, but even with 23
> years of work experience in the field, I decided to hire someone from
> this list and then just helped to snoop, test, debug and even hack the
> driver a little bit.  This experience taught me the basics of sane
> driver building and hacking and I can now appreciate some of the
> complexities of this. Of course, given enough time, you will
> eventually become an expert, but at least in my case I usually don't
> have much free time to head-bang at something that requires a very
> wide of skills and I'd rather focus my time on the expertise I already
> have. YMMV of course.
>
> Your best option IMHO is to download the Sane and Sane Backends source
> code and look at the existing Canon drivers. Who knows, the current
> drivers may even work with the 8400f, and you could contact the author
> of some of these drivers directly and perhaps they could dedicate some
> one-to-one time which you'll probably have to pay for but in my case
> it was completely worth it.
>
> Hope this helps,
>
> --
> Alejandro Imass
>
> --
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