[sane-devel] help for write back-end

[Bertrik Sikken]

corwin wrote:
> Hi,
> 
> I have a CanoScan 3200F (Product Id : 2216) and this scanner are not 
> supported by sane.
> But i'm very interresting for write a back end.
> 
> I use "usb snoopy log" for extract usb log under WinXP. And I had 
> writing a perl script (based on awk Thomas Soumarmon's script) for 
> genrate c code for replaying log-script under linux (debian, 2.6.9).
> For the moment I reading libusb documentation and my first objective is 
> to write a small program (sane independant) for activate the scanner.
> 
> But actually i'm completly lost into the log data and i don't know how 
> to begin !!!

Zip the logs and put them somewhere on your webpage (if you have one),
then post a link to the mailing list. This way, other people with
previous experience in decoding logs can try to see if there is
something that matches an existing protocol.

> So my questions :
> 
> Have you a methodology for extract information of data log ?

I think that there is no fixed methodology, you just have to be a
little creative.

In my experience it helps to look for patterns in the log, like:
* are there some USB transfers that always appear in some particular
   order?
* some scanners use a "register model", which means that initialising
   the scanner consists of several write(register, data), which each
   can consist of several USB transfers. See if this applies to your
   scanner and find out the sequence to read or write a scanner register.
* record lots of logs, where each time a single thing is changed, for
   example record a log of starting the scan software, record a log for
   a scan of 150 dpi, record a log for 300 dpi. If there is an option
   to turn the scanner lamp on or off, record a log of this.

For some scanners, the settings are sent using USB control transfers
or rather small USB bulk transfers. Try to concentrate on these small
transfers and don't bother too much yet about the bulky USB bulk
transfers that contain the image data.

> Where can I found script (perl, ..) for parsing and cleaning log data ?

I don't know of a central place for log analysis scripts.

> Have you trics ?
> 
> ludovic (corwin)
> 
> 
> ps: I don't know the model of chips into the scanner and i don't open 
> this because it is one plastic box and there are no visible screw...
> pps : I'm very sorry for my poor english :(
> 

Kind regards,
Bertrik


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