Hello, After a couple of months of other business I have again some time for hacking the CanoScan 3200F back-end. The current status is such that I am now working on the more reliable and safe speed curves and that may take some weeks to get working. Then I will resume working on the dark/white shading mechanism.
The reason I decided to do the ramps first is that the current system is really unsafe. In some cases the stepping motor will stall at start (too high acceleration) and the internal position counter, that relies on counting steps, gets out of sync. Now if the head is moved back it slams the stopper and I am not really sure if the HW has been designed to handle that. Therefore for the safety reasons the accelerations have to be handled so that the position counter stays in sync. Another problem currently, seen in the experimental back-end at 75-dpi is the trace-back acceleration. If back tracking is used light horizontal lines appear in the image. That is due to problems in the back tracking part of the speed curves and I will try to solve that too now. It seems likely that there is some misunderstanding in the way I currently use the sanei_usb library. That leads to problem that in some fast AMD64 machines the firmware verification fails -- in read-back the scanner NAK's. I have a stand-alone application that uses directly the libusb and does the firmware upload and restart of the scanner. Kristian Fiskerstrand reported that that application works in his system. If there are others requiring this temporary fix, please e-mail me. Then finally a word of warning. The experimental cs3200f backend is not intended for production use, only for experimenting and of course for soliciting input to the development. Therefore, please read the included cs3200f.txt and the warning in the beginning of that file, and do not include that back-end to a production build. In particular do not add cs3200f line to the dll.conf unless you are experimenting with this particular device since it will make the back-end show even if there is no actual HW, as a dummy device, due to the feature used in development. That feature will eventually be disabled but for now it will be kept there. With best regards, Lauri Pirttiaho Oulu Finland ................................................................... Luukku Plus paketilla p??set eroon tila- ja turvallisuusongelmista. Hanki Luukku Plus ja helpotat el?m??si. http://www.mtv3.fi/luukku
