[sane-devel] HP Scanjet 3670

Ralph Little skelband at gmail.com
Fri Dec 13 02:06:04 GMT 2019

I have a further question regarding gl646 protocol exchanges, in particular
related to the Scanjet 3670.

Looking at a USB trace from Windows for a 50dpi scan, I can see bulk
writing to the memory attributed to motor slope tables at 0x10000 and
0x10100, which is specified in the GL646 data sheet as being for 1200 DPI,
as set in DPIHW (register 0x05).
However, in the complete trace that I have, nowhere is register 0x05 ever
set to anything.
I see from the data sheet that the default value for register 0x05 is 0x00,
which would mean that 600dpi slope table areas should be used, at 0x08000
and 0x08100, which I do not see.

Yet the scanner works as expected.
Any ideas?

I feel like I'm so close to understanding gl646, but these few details
elude me.

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