[sane-devel] rts8891: Umax Astra 4450 does not work

[Ondrej Zary]

On Friday 29 May 2015 23:02:38 Ondrej Zary wrote:
> On Monday 11 May 2015 22:05:33 Stef wrote:
> > On 09/05/2015 00:32, Ondrej Zary wrote:
> > > On Friday 08 May 2015 21:46:36 Ondrej Zary wrote:
> > >> On Friday 08 May 2015 16:17:53 Ondrej Zary wrote:
> > >>> On Thursday 07 May 2015 23:32:28 Ondrej Zary wrote:
> > >>>> Hello,
> > >>>> I just got Umax Astra 4450 (same as 4400 except with UTA?) for a
> > >>>> while and tested it with SANE. Unfortunately, it does not work. The
> > >>>> lamp turns on and the head moves a bit, then goes back (two times)
> > >>>> and the scan ends with these errors:
> > >>>>
> > >>>> [rts8891] simple_scan: failed to wait for data
> > >>>> [rts8891] gain_calibration: failed scan data
> > >>>> [rts8891] sane_start: failed to do gain calibration!
> > >>>> scanimage: sane_start: Error during device I/O
> > >>>
> > >>> I've modified sane_start() in rts8891.c to not fail if
> > >>> gain_calibration() returns error. It now scans the complete area and
> > >>> the output resembles what's in the scanner (black template for UTA
> > >>> use with green text) but it's blurry, shifted horizontally (and the
> > >>> gain is wrong, of course):
> > >>> http://www.rainbow-software.org/linux_files/umax_astra_4450/no_gain_c
> > >>>al ib ra tion.ppm.gz
> > >>> http://www.rainbow-software.org/linux_files/umax_astra_4450/no_gain_c
> > >>>al ib ra tion.log
> > >>>
> > >>> Looks like there's a problem with the sensor type?
> > >
> > > Gain calibration fails because dev->left_offset (and thus xstart) is
> > > negative. If I set xstart to 4, gain calibration passes (although it's
> > > wrong: ends after first pass with 0x1f,0x1f,0x1f).
> > >
> > > So find_margin() does not work...
> >
> >      Hello,
> >
> >      you could try to hardcode gain values at the end of gain
> > calibration to see if scan is close to be correct.
>
> The dumps from Windows are very different. I've transferred the register
> settings to sane-rts8891 but with only partial success. 150dpi and 300dpi
> seems to work if I don't touch 0x7a register. 75dpi, 600dpi and 1200dpi are
> broken no matter what I tried.
>
> The experimental patch is available at
> http://www.rainbow-software.org/linux_files/umax_astra_4450/umax_astra4450-
>test.diff

Found a bug causing 600dpi scans to return only solid color area. It was a 
problem with 0xaa "escaping" - I misread the dump because of that and used 
wrong registers. After fixing, it didn't work at all - because the original 
sane-rts8891 code does not "escape" 0xaa values in registers above 0xb3. 

After fixing that, 600dpi is still broken but at least some real data is 
coming from the scanner now.

New patch:
http://www.rainbow-software.org/linux_files/umax_astra_4450/umax_astra4450-test2.diff

-- 
Ondrej Zary