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Thread: New LCD problems

  1. #1
    Newbie
    Join Date
    Feb 2001
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    13

    Unhappy New LCD problems

    Here's the story:

    Today I bought a 24x2 LCD display at a surplus store for $14.95CAN. Pretty good price.I ripped off the connector, and soldiered a bunch of wires into it, and then wired it up to a parallel port connector. It's a 14 pin connector. I plug it in, and load up some software, it recognises it, but the screen won't display anything.

    I think it's the contrast, but I have a contrast wire, and if i touch it to either +5 or ground, it does nothing. I'm not sure what's wrong. I've gone over the wiring about a billion times and it all seems to check out.

    If it helps, it has a HD44780a00 chip, and 2 HD44100H chips.


    Help.

  2. #2
    FLAC
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    Jan 2001
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    Post

    Contrast should go to ground

    as for no output check the delay settings in the program you are using (you might need to increase the #.


  3. #3
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    Feb 2001
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    i'm using winamp plugins, and an lcd test prog off the net.

    The data is getting to the lcd, I just can't see it. Nothing, not even little boxes at startup.

  4. #4
    FLAC
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    Jan 2001
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    Post

    hmm...

    try ckecking all of the connections

    LPT Pin: LCD Pin:
    GND 1 (GND)
    Use External 5V 2 (+5V)
    GND 3 (GND Contrast should be connected to variable resistor, but this works for me!)
    16 4 (RS)
    14 5 (R/W If Reading not used, tie to GND)
    1 6 (E)
    2 7 (D0)
    3 8 (D1)
    4 9 (D2)
    5 10 (D3)
    6 11 (D4)
    7 12 (D5)
    8 13 (D6)
    9 14 (D7)

    From: http://members.tripod.com/padara/lcd_info.htm


    then apply +5 to lcd pin 2 and ground to lcd pin 1

    you should see one solid line of dark blocks

    [This message has been edited by bgoodman (edited 02-24-2001).]

  5. #5
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    Feb 2001
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    nothing.

    I know the screen is working, I tried connecting the contrast to a pos source, and the +5 in to a gnd and the gnd to the gnd, and I got a screen of black.

  6. #6
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    Feb 2001
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    A little more info:

    When I connected my multimeter, it says that the circuit was drawing .5 amps on the +5, and the HD44780 chip got very hot. I'm no expert, but it shouldn't get this hot.

  7. #7
    Newbie
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    Feb 2001
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    13

    Red face

    Oh ****. Nevermind. I figured it out. I was reading the pins backwards.

  8. #8
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    Feb 2001
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    It works! Sort of.

    I have a bottom row of black boxes. From what I have read on the net, this is what is displayed when there is no signal.

    The programs keep coming up saying lcd not connected, and the boxes on the lcd darken for a second as the program scans the port.

    [This message has been edited by annoyingrob (edited 02-25-2001).]

  9. #9
    FLAC
    Join Date
    Jan 2001
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    Post

    depending on what winamp lcd plugin your using it may or may not work.
    my 2x20 didn't work with inmotion's plugin but it did with mpxplay ( http://www.geocities.com/mpxplay/ )
    and lorty's lcd plugin( http://lorty.mp3car.com/ )

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