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Powertip lcd graphic panel

Discussion in 'Electronic Design' started by colin, Dec 8, 2006.

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  1. colin

    colin Guest

    Hi
    I have one of these wich im driving from a dspic30f
    http://www.powertipusa.com/pdf/pg320240c.pdf
    but the data sheet leaves a bit to the imagination !
    I have a chequor display but wich can only be seen if the scan is reduced to
    a crawl
    then only one line can be seen at a time,
    vee is -27v.
    im not sure if the contrast voltage should be 0-5v as other displays or as
    some1 suggested on sci.electronics.components
    is possibly a negative input ?
    anyone have any experience of this make/type of panel ?

    thanks
    Colin =^.^=
     
  2. colin

    colin Guest

    Well thankfully I got it working a lot better now, thanks to poly' who
    sugested the negative contrast voltage wich was indeed the case,
    I just fed it -vee through a 1M then 100kR to be safe and it displayed ok.

    heres the bit bashing code ..

    s=display_text[row/8];
    pixels=font8bitmap+(row%8)-font8start*8;
    for(col=0;col<no_cols/8;col++)
    {
    c=*s++;
    LCD_CL2=1;
    b=pixels[c*8];
    D0_D4=b>>4;
    b&=0xf;
    LCD_CL2=0;
    LCD_CL2=1;
    D0_D4=b;
    LCD_CL2=0;
    }
    LCD_CL1=1;
    if(!row)
    LCD_FLM=1;
    LCD_CL1=0;
    LCD_FLM=0;
    if(++row>=no_rows)
    {
    row=0;
    LCD_M^=1;
    }


    Now I just need a way to avoid making an EL driver transformer with
    thousands of turns.

    Colin =^.^=
     
  3. Would a trigger transformer for a xenon tube work for that? (I haven't
    thought this through, the idea just came to me so I put it forward as it
    is).
     
  4. Don McKenzie

    Don McKenzie Guest

    Out of interest, what -vee level did you need to use?

    Don...


    --
    Don McKenzie
    E-Mail Contact Page: http://www.dontronics.com/e-mail.html

    Crystal clear, super bright OLED LCD (128x128) for your microcontroller.
    Simple serial RX/TX interface. Many memory sizes.
    http://www.dontronics-shop.com/product.php?productid=16460
     
  5. colin

    colin Guest

    about -18v to -22v seems to work ok, depends on the refresh rate etc.

    Colin =^.^=
     
  6. colin

    colin Guest

    not sure, but the problem is the frequency wich is a bit low +~ 4khz
    wich means a lot of turns at 200v to avoid saturation.
    trigger transformer probably only expects very short pulses
    although I dont know how many turns it has.
    needs aprox 3k turns with 12mm^2 ferrite core.

    looking around a way to do it seems to exist wich uses a simple switch mode
    200vdc generator and simply pulsing it on and off at 4khz. im wondering how
    I can combine this with the -20v bias generator.

    Colin =^.^=
     
  7. The facetious answer would be: "don't" >:) That negative voltage bias is a
    very low-current signal to a sensitive device, it might be asking for
    trouble to try to integrate those two systems.

    Good idea with the switch mode supply transformer though, far more likely,
    and they often turn up free on all kinds of stuff.
     
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