[sane-devel] Canon LiDE 90

[Pierre Willenbrock]

Hi,

Guillaume Gastebois schrieb:
> Hello,
> 
>> So, we need to check what parts of the clocking we need to setup
>> differently.
>>
>> Candidates:
>>
>> reg   sane  windows
>> 0x1a  0x00  0x24     enable clock 3,4 manual output, invert clock 4
>> 0x1d  0x04  0x02     just a smaller toggle "shoulder".
>> 0x71  0x00  0x05     RS signal seems to be not used.
>> 0x72  0x00  0x07     CP signal seems to be not used.
>> 0x73  0x00  0x09     CP signal seems to be not used.
>> 0x75  0x00  0x01     clock 1 bitmap
>> 0x76  0x00  0xff     clock 1 bitmap
>> 0x79  0x00  0x3f     clock 3 bitmap
>> 0x7c  0x00  0x1e     clock 4 bitmap
>> 0x7d  0x00  0x11     change RS on falling edge of system clock, use DLY
>> 0x7f  0x00  0x50     delay each of BSMP and VSMP by 8.33ns (DLY)
>>
>> The clock 1 stuff seems to be not needed, as it is in automatic mode.
>> But clock 3/4 look interesting. The delay of BSMP/VSMP may be useful, too.
>>
> 
> 0x1a was still 0x24. I modified 0x1d which was 0x04 to 0x02. Result is 
> on http://ggastebois.free.fr/lide90_snoop/22_test1.tar.
> 
> I doesn't find where to modify 0x71-0x7f !!!

Add them to gl841_init_registers.

>>> Another thing : I always have a brither vertical line where there is a
>>> small black rectangle in the calibration area.
>> The small black rectangle is included when acquiring the white level.
>> Reduce shading_lines(second to last entry) in Genesys_Model to 250, that
>> way it is not seen anymore.
>>
> 
> Done, works.
> 
>> Oh, and please update from cvs again. A small mistake in
>> gl841_bulk_write_registers made the debug register dumps useless.
>>
> 
> Done.
> 
> 
> Another thing : when I make several scan with sane backend and sane 
> command line, I have alternatively brite and dark images !!! Why ???

The calibration is probably giving widely differing results with
different starting conditions. It swings between two states. But you
shouldn't see this after the gl842 did its shading correction. Then, the
problem is probably overexposure of the ccd cells. Try reducing the
upper threshold in genesys_gl841.c:4383

	  if (avge > 2000) {
	      expr = (expr * 2000) / avge;
	      expg = (expg * 2000) / avge;
	      expb = (expb * 2000) / avge;

Reducing the lower threshold may be needed, too. The current values for
your scanner are:
expr: 1235
expg: 1235
expb: 675

No guarantee that this helps at all.

> Regards
> Guillaume

Further, we need to figure out a way to get the LEDs go completely dark.
0x101 is just about half of 675. I will experiment a bit with my
scanner, to find out if the gl842 can do that.

Regards,
  Pierre