On 1/5/08, Marco Freudenberger <Marco.Freudenberger at gmx.de> wrote: > Hi list .... > > I'm urgently looking for a backend driver for a Plustek PL 812 (USB / > ADF + Flatbed) scanner. Looks like there's (bu-huuuu) currently no > backend that supports it.
[snip] > But it would be great if somebody could help me alittle to bring me on > speed making the first baby steps. I plan to use a USB sniffer > (hardware) on the PL-812 on Windows to try to reverse engineer the > protocol. I don't think this will be the worst part. But actually, I > don't know where to start with developing and have a few questions to > the more experienced guys out there: > > 1) the backend-writing doc > (http://www.sane-project.org/backend-writing.txt) suggest to start with > a standalone test programm. Is there some kind of a framework or > existing test programm that can be modified for starting ? if you use benoit's usbsnoop instead of a hardware sniffer, there is a program (usbsnoop2libusb) which will turn that into a c prog that you can hack on. it cannot interpret the meaning of the packets, but it can be a good place to start. there are also programs in the usbsnoop dir of the sane experimental tree, which can clean up logs from usbsnoop as well. i am fond of spike4.pl myself :) > > 2) the same document suggest (sounds like a good plan!) to extend > existing backends whenever possible or use existing backends as a > starting point at least. Any idea which one could be a good starting > point for the PL-812 ? open the scanner and figure out what chips are in it. it may already be supported by an existing backend, just needs some tweaks to know about that model. > 3) Is there any further documentation out there to get me on speed ? Or > books on that subject-matter (also the relevant parts of Unix / USB > programming that might be needed) ? google for 'usb in a nutshell', and the usb 1.1 specs. the libusb docs are almost useless. > 4) What is an ususal ammount of time one would plan for developing a > backend for a certain scanner ? from a couple hours if it is an already supported chip, to hundreds of hours if it is completely new and you have no docs. > 5) BTW, my environment will be a Kubuntu Linux distribution. Anything > special about that ? nope, as long as you install the libusb devel headers and gcc, you should be good. > Thanks for your help! I know, those questions sound like I will never > make that happen in a reasonable ammount of time, but once I know where > to start that will change - I'm really a good and incredible quick > developer, usually ... i used to say the same thing, until i developed the epjitsu backend with no docs. i dont know if i will ever do that again... :) allan -- "The truth is an offense, but not a sin"
