[Coco] Last video I promise... :)

Fri Dec 5 11:09:52 EST 2014

Ok finally my mules decided to arrive and I assembled one for me.

I don't get the noise you have there, but I noticed there is a small noise.
My prototype doesn't have this. The culprit is the VGA ouput. In my
prototype I have placed them far away from the input lines. But in the new
design i tried to make things more compact and I sucked on this :P

Well, modifying the FPGA I have reduced the amout of noise changing the
input/output currents. You can check whether your noise is the vga by doing:

screen 80
cls 4
dir

Check if the noise increases as the amount of the text on screen also
increases. In your video, when you blast the trimmers, I can clearly see
blanking lines waving, so it must be it.

How to solve this completely ? Redesign the board ? Using a faraday cage ?

Update your repo and try the new version. it might help.

Regarding the colors, you may notice that some colors have a "noise
pattern" on that, look that this partern doesn't run, it has some
flickering but they stay put.

This is not external interference, it's merely slack time that is affecting
how the colors are digitized. Let's say: the altera is running the code at
the limit of it's speed. This cause the code to get out of sync with the
clock and then, the color is digitized in the wrong level of the DAC, or it
didn't have time enough for the differential to change its value. Solving
this is much more difficult.

The first thing is to remove and simplify the code, this means no more
artifacting colors, and other stuff. This would help getting a stable
timing though.

Luis Felipe Antoniosi

On Fri, Nov 28, 2014 at 11:11 PM, Richard Goedeken <
Richard at fascinationsoftware.com> wrote:

> Hi Luis,
>
> Here are new images of the board and the video output:
>
> http://www.fascinationsoftware.com/media/rgb2vga/IMG_9763.JPG
> http://www.fascinationsoftware.com/media/rgb2vga/IMG_9766.JPG
> http://www.fascinationsoftware.com/media/rgb2vga/IMG_9768.JPG
> http://www.fascinationsoftware.com/media/rgb2vga/IMG_9770.JPG
> http://www.fascinationsoftware.com/media/rgb2vga/IMG_9775.JPG
>
> Unfortunately, grounding the connector shield didn't fix the noise issue;
> it's
> still there like before.  I'll have to consider all of the various devices
> that are plugged in, and see if there is a ground loop there somewhere.  I
> am
> using 1% resistors for the 75 ohms.  Do you have any suggestions for
> improving
> the color fidelity?  What changes did you make to the FPGA code to
> customize
> it for your particular Coco?
>
> Richard
>
> On 11/28/2014 05:55 PM, Luis Antoniosi (CoCoDemus) wrote:
> > now I saw the video.
> >
> > First question: which program is that ? How do I get it. It's very nice
> for
> > testing the colors.
> >
> > Second, can you take a picture of your board ? bottom/top ?
> >
> > There is indeed a noise band rolling. I don't get these, but my board
> from
> > osh park DIDN"T ARRIVE YET. I takes a month to cross the canadian border.
> > Dude they must put them on the back of mules. Cannot explain that.
> >
> > Then check the grounding. Make sure everything is grounded from coco,
> > altera and the monitor. (make sure the outer shell is grounded as I
> said).
> > It's getting there, the image is pretty good already.
> >
> > Also, do you have MPI or any other device  on your coco ? I'm always
> > testing with either superIDE or CocoSDC but never mpi. Just try the coco
> > without any device and check the 32 and 80 columns screens:
> >
> > width 80
> > 10 for n=32 to 255
> > 20 print chr$(n);
> > 40 next n
> >
> >
> >
> >
> > Luis Felipe Antoniosi
> >
> >
> >
> > On Fri, Nov 28, 2014 at 8:02 PM, Richard Goedeken <
> > Richard at fascinationsoftware.com> wrote:
> >
> >> Hi Luis,
> >>
> >> Thank you so much for designing the awesome video converter and making
> all
> >> the
> >> plans available.  I built one up yesterday and hooked it up to my Coco
> 3,
> >> and
> >> it works, but there is some noise in the video output and the colors are
> >> not
> >> exactly right.  Can you help me get it working?
> >>
> >> I uploaded a video which shows the problems very well.  It's raw mpeg2ts
> >> (AVCHD) at 1080i 60hz from my video camera; the file is about 131MB.  I
> >> didn't
> >> want to upload it to youtube which would crush the resolution and frame
> >> rate.
> >>  You should be able to view it with VLC or mplayer or similar:
> >>
> >> http://www.fascinationsoftware.com/media/Coco3-RGBVGA.mts
> >>
> >> In the video, I turn the 10k potentiometer up and down to show how it
> >> affects
> >> the colors.  You can see that there are some rolling bands of noise in
> the
> >> brightness values of the pixels.  And many of the colors seem to be the
> >> same
> >> shade.
> >>
> >> The test screen output (when the Coco is turned off) is perfect, so the
> >> problem is with the input section.  I wasn't sure exactly which build of
> >> your
> >> FPGA code I should use.  And I've never used FPGA tools before, so there
> >> was a
> >> little bit of a learning curve in installing the tools and using them.
> >> But I
> >> ended up with the latest git clone from the github repo (as of
> yesterday),
> >> and
> >> I used the Quartus programmer tool to write the output_file.jic into the
> >> serial eeprom loader memory.  Should I have used a different version?
> Do I
> >> need to compile the fpga code?  It looks from your repo that you update
> the
> >> SOF and JIC files with every commit, so I assume that means I don't
> need to
> >> compile the project if I don't make any of my own changes.
> >>
> >> Any ways, thanks again for this great product, and I hope I can get it
> >> working
> >> here.
> >>
> >> Richard
> >>
> >> On 11/11/2014 05:03 PM, Luis Antoniosi (CoCoDemus) wrote:
> >>> It's all here:
> >>>
> >>> https://sites.google.com/site/tandycocoloco/rgb2vga
> >>>
> >>>
> >>> Luis Felipe Antoniosi
> >>>
> >>>
> >>>
> >>> On Tue, Nov 11, 2014 at 7:23 PM, Mark McDougall <msmcdoug at iinet.net.au
> >
> >>> wrote:
> >>>
> >>>> On 12/11/2014 2:42 AM, Luis Antoniosi (CoCoDemus) wrote:
> >>>>
> >>>>  Let's say: everytime you add a switch and a if condition the code
> >> splits
> >>>>> in
> >>>>> two and the fpga seems to execute both. It's all parallel. It's hard
> to
> >>>>> understand...
> >>>>>
> >>>>
> >>>> Is the code public? I can attempt to explain it if you're interested?
> >>>>
> >>>> Regards,
> >>>>
> >>>> --
> >>>> |              Mark McDougall                | "Electrical Engineers
> do
> >> it
> >>>> |  <http://members.iinet.net.au/~msmcdoug>   |   with less
> resistance!"
> >>>>
> >>>> --
> >>>> Coco mailing list
> >>>> Coco at maltedmedia.com
> >>>> https://pairlist5.pair.net/mailman/listinfo/coco
> >>>>
> >>>
> >>
> >> --
> >> Coco mailing list
> >> Coco at maltedmedia.com
> >> https://pairlist5.pair.net/mailman/listinfo/coco
> >>
> >
>
> --
> Coco mailing list
> Coco at maltedmedia.com
> https://pairlist5.pair.net/mailman/listinfo/coco
>