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VGA Pins — Parallax Forums

VGA Pins

NewzedNewzed Posts: 2,503
edited 2007-06-05 00:15 in Propeller 1
For Paul Baker:

Paul, I built up an LED array for the VGA pins - like the Demo board but with red SMD LEDs.· I have 270 ohms in series with each of the eight resistors.· All of the LEDs burn, but some are much brighter than others.· Using Pins 8-15, Pins 9 and 14 are the brightest.· I gather Pins 8 and 9 have to do with font, and that the three pairs determine RGB.· Could you tell me that max voltage I might get on all 8 pins?· I would like to make the resistors smaller so the low level LEDs will burn a bit brighter, but I don't want to overdo it.

Thanks

Sid

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Yesterday is history, tomorrow is a mystery, and today is a gift.

That is why they call it the present.

Don't have VGA?
Newzed@aol.com
·

Comments

  • Paul BakerPaul Baker Posts: 6,351
    edited 2007-06-04 21:01
    Sid, is this observed behavior when you are running the VGA port, or when you are not and just running the LEDs directly?

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    Paul Baker
    Propeller Applications Engineer

    Parallax, Inc.
  • NewzedNewzed Posts: 2,503
    edited 2007-06-04 21:41
    Paul, this is when the VGA is running and the eight LEDs are connected just like on the Demo board.· I can see activity when I do something to change the VGA display - I would just like some of them to be a bit brighter than they are now.

    Glad you're back from vacation - hope it was outstanding!

    Sid

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Yesterday is history, tomorrow is a mystery, and today is a gift.

    That is why they call it the present.

    Don't have VGA?
    Newzed@aol.com
    ·
  • Paul BakerPaul Baker Posts: 6,351
    edited 2007-06-04 23:12
    Well it went longer than anticipated, as I was waiting for my return flight I found out grandfather was sick and had to make last minute travel arangements down to your neck of the woods (I grew up in FL and family is still there), he's doing better now.
    The reason some of the lights are dimmer than others is because of the PWM effect caused by each line being driven at an independent frequency. Unfortunately this is completely dependant upon what is being displayed on the VGA monitor. Try making the screen entirely white first and see if this helps the situation. If you find some of the lines still dim you could try to decrease the resistor value for that line, but pay attention to whether this affects the video display. If it does go back to your previous value.

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    Paul Baker
    Propeller Applications Engineer

    Parallax, Inc.
  • NewzedNewzed Posts: 2,503
    edited 2007-06-04 23:32
    Where in Florida - close to Port Richey?

    I might play around with changing the resistors values.· It's a bit tough because the LEDs and resistors are all mounted on a little board I made less than an inch square.

    Sid

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Yesterday is history, tomorrow is a mystery, and today is a gift.

    That is why they call it the present.

    Don't have VGA?
    Newzed@aol.com
    ·
  • Paul BakerPaul Baker Posts: 6,351
    edited 2007-06-05 00:15
    A couple hours from there in the Avon Park/Sebring area.

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    Paul Baker
    Propeller Applications Engineer

    Parallax, Inc.
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