[sane-devel] Plustek OpticPro 1212U / HP ScanJet 4200C

Albert ARIBAUD albert.aribaud@free.fr
Wed, 26 Nov 2003 10:23:51 +0100

Hi Gerhard,

Le mar 25/11/2003 à 19:01, Jaeger, Gerhard a écrit :

> The bridge is GeneSys Logic GL640  chip.

> Okay, go on with that - my code here is called u12, and therefore
> the backend will be called u12...

> Well, probably we should share the code I started with...
> I'll try and setup some info on the plustek-backend download site
> at www.gjaeger.de - I'll keep you informed on that. In the meantime,
> you should check the general SANE-docs for information 'bout writing
> backends...

I see that the canon fb630u backend is divided in two source files : one
for the backend as such, and one for driving the GL640, providing basic
EPP instructions plus scanner-specific data transfer sequences. Makes me
wonder whether this backend was built by splitting the corresponding EPP
backend into scanner-level and port-level operations, the modifying the
port-level part.

So maybe a solution for the OpticPro 1212U would be to i) adapt the
scanner-specific sequences using traces from Twain scans under windows,
and ii) integrate the adapted GL640 file with the existing 98003-based

Another choice I see is taking the GL640 code and turning it into a
pseudo ieee1284 kernel module or an extension to the ieee1284 lib. Then
we could use the genuine 98003-based backend. But this seems not to be
design choice for the fb630, so it might be a more bug-attracting

BTW, I have not yet compared the EPP and USB versions of the Canon
fb630, but maybe those scanner-specific sequences exist in both
scanners, i.e. they are at ieee1284 level, not GL640. If so, then the
sequences for the OpticPro 1212u must be found in the PT12-specific

(I must admit not having the scanner handy makes things uneasy for me,
but then by brother (whom I am trying to help) is willing to help

Have a nice day,
Albert ARIBAUD <albert.aribaud@free.fr>