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Scope Display (Microphone to VGA) — Parallax Forums

Scope Display (Microphone to VGA)

cgraceycgracey Posts: 14,287
edited 2009-05-14 15:23 in Propeller 1
This is for Propeller Demo Board Rev C's.

The microphone gets digitized and displayed on a VGA monitor like a scope trace, complete with auto-level triggering.

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Chip Gracey
Parallax, Inc.

Post Edited (Chip Gracey (Parallax)) : 6/9/2006 9:44:58 AM GMT
zip
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microphone_to_vga - Archive [Date 2006.06.09 Time 02.34].zip
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ScopeVGA.jpg
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Comments

  • Kaos KiddKaos Kidd Posts: 614
    edited 2006-06-09 14:42
    Chip, what is the reason for these lines?

    'fill top line so that it gets erased by COG
    longfill(@pixels, $FFFFFFFF, vga#xtiles)

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Just tossing my two bits worth into the bit bucket


    KK
    ·
  • cgraceycgracey Posts: 14,287
    edited 2006-06-09 18:03
    For each X, the assembly program erases the old pixel at the old Y and plots the new pixel at the new Y. It also updates the word that holds the Y. So, the first time the loop runs, it is going to erase some pixels. The Y buffer for all those pixels is in a VAR, so it is initialized to all zeros. By plotting a line across the top of the screen (Y=0), you give it something to erase, leaving the rest of the screen looking normal afterwards. If you didn't preset those pixels, they would get XOR'd on, and there would be a line at the top of the screen.
    Kaos Kidd said...
    Chip, what is the reason for these lines?

    'fill top line so that it gets erased by COG
    longfill(@pixels, $FFFFFFFF, vga#xtiles)

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔


    Chip Gracey
    Parallax, Inc.
  • Kaos KiddKaos Kidd Posts: 614
    edited 2006-06-09 18:31
    Ahhh... I see... thanks.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Just tossing my two bits worth into the bit bucket


    KK
    ·
  • neotericneoteric Posts: 144
    edited 2009-05-14 01:35
    Chip,
    Could you explain for me a quick question? How do I tell know where to actually wire the VGA pins? Is basepin the first line, y (16) then v (17) etc.? Just getting started, sorry if this is an obvious one...

    PS, you would not believe how much I have searched just trying to get started on this....
  • hover1hover1 Posts: 1,929
    edited 2009-05-14 01:57
    neoteric said...
    Chip,
    Could you explain for me a quick question? How do I tell know where to actually wire the VGA pins? Is basepin the first line, y (16) then v (17) etc.? Just getting started, sorry if this is an obvious one...

    PS, you would not believe how much I have searched just trying to get started on this....
    @neoteric

    Download the following schematic for the Parallax Demo Board:
    http://www.parallax.com/Portals/0/Downloads/docs/prod/prop/PropDemoDschem.pdf

    Simple D/A conversion for VGA from the Prop. I think that is what you are asking.

    Jim
  • Dr_AculaDr_Acula Posts: 5,484
    edited 2009-05-14 02:18
    Yes, that circuit using those pins has become a de-facto standard for all sorts of prop projects. I've just finished harvesting a D15 plug off an old PC motherboard I got for free at my local computer store. Nothing you can't salvage with an angle grinder and a blowtorch!
  • Toby SeckshundToby Seckshund Posts: 2,027
    edited 2009-05-14 09:38
    Thats being really subtle, James. Small therm-nuclear charges get the aukward bits off.

    The downside of scrounging old bits is that you seldon get two idendical types of anything.
  • neotericneoteric Posts: 144
    edited 2009-05-14 15:23
    Thanks so much for the help.· I thought that was a simiple question, but I couldnt find verification.



    ·Thats what· I thought.· Full speed ahead.
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