[Elphel-support] RedZone Elphel 353

[Andrey Filippov]

Hi Yu Li,

The "purple image" with the older code is related to the internal
behavior of the Aptina sensors. More precisely - when the input clock
to the sensor is restarted, the internal PLL can start so that
internal odd/even pixel counter is at opposite phase. Interestingly,
that is different for the sensor-generated test pattern and the actual
image. So the test pattern can be with correct colors and the acquired
images - with wrong ones. And that phase is not reset by the sensor
reset signal - only by the power-cycling

In older software we compensated the cable delay (from FPGA to sensor
and from sensor - to FPGA) by adjusting phase of the clock to the
sensor while keeping the input clock fixed (and common with the FPGA
circuitry that runs at pixel and double-pixel rate. We do not use
sensor output clock to keep the internal FPGA clock stable and
independent of the sensor state.

We tried but did not succeed to completely understand what sensor
"likes" or "does not like", so the later code does not adjust clock
phase to the sensor but rather adds input module   to the FPGA, so the
sensor data is latched at arbitrary phase to the FPGA internal clock
and then synchronized to that FPGA clock using a small FIFO.

The changes in the new code are on all levels - FPGA, drivers,
applications. What exactly terms of the GNU GPLv3 that are different
from the GNU GPLv2+ are not compatible with the RedZone requirements?
Our older software (including the one you had) uses GNU GPLv2, so
distributing of modified code (including FPGA) to the customers has to
be compliant with it. All that is described on our
http://www3.elphel.com/importwiki?title=GNU_GPL_FAQ is applicable to
that older software too.

Andrey

On Wed, Mar 14, 2012 at 2:59 PM, Li, Yu <yli at redzone.com> wrote:
> Hi,
>
> I am Yu Li from RedZone Robotics.  We used your Elphel 353 camera in our
> product.  We have the purple image issue.  We need help.
>
> We had several peoples contacted you before.  Now I was working on it.
> Since I was new to this issue, and I don't have all the information
> available, please help me out.
>
> First, I need understand the issue.  My understanding is
> The camera that we are using has the purple image issue.  You released a new
> rev. of the software, and fixed this issue.  But because of the licensing or
> copy right issue, RedZone could not move on with your new software.  We use
> 353-7.1.5.
>
> The software includes Elphel software and FPGA code.
> For your new software that fixed the purple image, I want to know if the
> changes were made in Elphel software (lib?), or FPGA, or Elphel software
> (lib?) and FPGA.
>
> Let me stop here.  I will have more questions after your answer.  I just try
> to see if there is a way you and us can work together to solve our problem.
>
> Thanks.
>
> --
> Yu Li
> Lead Engineer
> RedZone Robotics, Inc.
> 91 43rd Street
> Pittsburgh, PA 15201
> 412-476-8980 x 287
> 412-476-8981 (fax)
>
>
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