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Unwanted blink in LED's — Parallax Forums

Unwanted blink in LED's

GTV61GTV61 Posts: 2
edited 2008-09-28 04:49 in BASIC Stamp
I am trying to dim up and dim down some led's. I used the following code
' {$STAMP BS2}low
' {$PBASIC 2.0}
Counter VAR Word
Full VAR Word
Full = 2310
·Pulse
FOR Counter = 0 TO Full STEP 15
PAUSE 5
PULSOUT 9,counter + 1
·NEXT
FOR counter = Full TO 0 STEP 15
PULSOUT 9,counter + 1
·PAUSE 5
NEXT
·GOTO pulse

The Led's are powered thru a ULN2003A driver·

I does what I need however as the led's get to their full brightness there is a small very short but noticable blink.
Q: Does anyone know why and how do I remove it?

Post Edited (GTV61) : 9/26/2008 5:23:44 PM GMT

Comments

  • deadwhaledeadwhale Posts: 30
    edited 2008-09-26 16:29
    I'm just guessing because this is all new to me too, but without seeing

    how you've got everything hooked up it probably blings when it goes back to the start

    of the program. Perhaps a capacitor in there someplace to help hold the charge for just a

    bit would stop the blink???



    Oh, and someone is going to tell you to edit your subject (put a subject in)· confused.gif

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    Prune Free.
  • GTV61GTV61 Posts: 2
    edited 2008-09-26 16:57
    YEA I tried a few differrent caps and it doesnt really help. Plus it changes the Dim rate.
  • $WMc%$WMc% Posts: 1,884
    edited 2008-09-28 00:49
    GTV61
    You didn't say what kind or how many LEDs your powering, But I think your useing the Vishay Telux Ultra Super Brite LEDs Part# TLWW9900 or simular,If so;These LEDs are current hogs, Yes I said Power Hogs,They need a TON of current to reach full illumiation.While I don't think it is brownin out the $stamp, It could be·putting the ULN2003A into thermal overload for a brief few mSec.s.I would check the current draw @ the Vdd/Vss pins on the ULN2003A to see if its overloaded @ peak output...

    This is all I can offer w/ the info. you gave
    $WMc%___out

    Post Edited ($WMc%) : 9/28/2008 12:54:54 AM GMT
  • Dave-WDave-W Posts: 94
    edited 2008-09-28 00:58
    GTV61,

    Try this to see if it helps?

    Just a thought.



    I am trying to dim up and dim down some led's. I used the following code

    ' {$STAMP BS2}low
    ' {$PBASIC 2.0}
    Counter VAR Word
    Full VAR Word
    Full = 2310
    ·Pulse
    FOR Counter = 0 TO Full STEP 15
    PAUSE 5
    PULSOUT 9,counter + 1
    ·NEXT
    '
    ' keep output 9 high
    '
    high 9
    '
    FOR counter = Full TO 0 STEP 15
    PULSOUT 9,counter + 1
    ·PAUSE 5
    NEXT
    ·GOTO pulse

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    Dave W.
  • MikerocontrollerMikerocontroller Posts: 310
    edited 2008-09-28 01:19
    · I noticed you are using version 2.0 of the Basic Stamp editor.· I use version 2.5 and I get an error

    message if I don't use a colon after the address name (pulse).· I don't know if this will help...
  • MikerocontrollerMikerocontroller Posts: 310
    edited 2008-09-28 04:49
    Ignore my last post. It works without the colon. You can always have your program begin by flashing an LED, beeping a sound, or printing to the debug screen so you will know if the program has restarted. It certainly will help
    eliminate that possibility in your troubleshooting.
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