[sane-devel] Problem with sane-backends-1.0.8-pre1 and HP Scanjet 2200C

[Ville Hallik]

There is a big problem with HP 2200C (and possibly other USB scanners
supported by plustek backend). The difference between values stored in
registers 0x4e and 0x4f (pause/resume scan when buffer is n*x kB full) is
too small. Scanning starts normally but once the buffer gets full, the
scan head starts to cycle forward and backward too quickly (changes
moving direction many times per second). The problematic code is in file
backend/plustek-usbscan.c at lines 1085-1088:

/* original code:
 *      a_bRegs[0x4f] = 1;
 */
        a_bRegs[0x4f] = a_bRegs[0x4e] - 1;

The easiest solution is to revert back to the original code (as in
sane-1.0.7) that just sets register 0x4f to one.