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Parallax 4x20 LCD (test) NOT WORKING — Parallax Forums

Parallax 4x20 LCD (test) NOT WORKING

computer guycomputer guy Posts: 1,113
edited 2010-01-30 18:33 in General Discussion
Hi,

I got my Parallax 4x20 serial LCD in the mail today and uppon switching it to "test" mode and connecting a regulated 5V supply from the proto board I get random black squares on the display and nothing else. I have changed the contrast and all this does is change how dark the squares are.

Has anyone had this happen to them or know how I can resolve the issue.



Thank you smile.gif

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Comments

  • computer guycomputer guy Posts: 1,113
    edited 2009-12-30 07:18
    I have tried turning off "test" mode and it is exactly the same except that the backlight turns on.

    I have attached a photo of what it is doing.
    Sorry for the bad quality, I used my phone.

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    LCD problem.jpg
    495 x 278 - 45K
  • James LongJames Long Posts: 1,181
    edited 2009-12-30 07:28
    computer guy said...
    I have tried turning off "test" mode and it is exactly the same except that the backlight turns on.

    I have attached a photo of what it is doing.
    Sorry for the bad quality, I used my phone.

    Hmmmm.....that doesn't look good.

    I would think something is definitely wrong.

    You may have to wait for Parallax to answer this one.

    James L

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    James L
    Partner/Designer
    Lil Brother SMT Assembly Services

    Are you addicted to technology or Micro-controllers..... then checkout the forums at Savage Circuits. Learn to build your own Gizmos!
  • computer guycomputer guy Posts: 1,113
    edited 2009-12-30 07:52
    It isn't a bug that when the RX pin is floating it does strange stuff by any chance?
    I figured this shouldn't be the case in "test" mode. But just a thought.

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  • James LongJames Long Posts: 1,181
    edited 2009-12-30 08:00
    computer guy said...
    It isn't a bug that when the RX pin is floating it does strange stuff by any chance?
    I figured this shouldn't be the case in "test" mode. But just a thought.

    Now that I do not know.

    I would think that with power and ground. The display would normally just show a cursor, waiting on a command, but I may be wrong.

    With RX floating, it may cause problems. You could tie it to ground to see what happens. That shouldn't hurt anything (I'm guessing here.....)

    James L

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    James L
    Partner/Designer
    Lil Brother SMT Assembly Services

    Are you addicted to technology or Micro-controllers..... then checkout the forums at Savage Circuits. Learn to build your own Gizmos!
  • computer guycomputer guy Posts: 1,113
    edited 2009-12-30 08:03
    Tried it just then. Made no difference. I'm guessing it's DOA.
    Parallax?

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  • James LongJames Long Posts: 1,181
    edited 2009-12-30 08:12
    I was just going to post again......

    I knew something was wrong. With the propeller the pins start in a state which would cause the RX pin to float. That doesn't do what you show.

    So.....you are right.....it's Parallax time.

    James L

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    James L
    Partner/Designer
    Lil Brother SMT Assembly Services

    Are you addicted to technology or Micro-controllers..... then checkout the forums at Savage Circuits. Learn to build your own Gizmos!
  • mikedivmikediv Posts: 825
    edited 2009-12-30 17:11
    computer guy it has to be dead I have the same one just 5 volts and ground in test mode it will do a little demo program for a few seconds showing some of the displays capabilities.
    I didn't think to ask but did you solder any connectors to it? If you did just double check for shorts ,, just a thought I hate getting bad parts you want to believe its anything but broken so your mind tries to think up stupid stuff even though deep down you know its a bad part LOL
  • computer guycomputer guy Posts: 1,113
    edited 2009-12-30 22:01
    Thanks Mike,

    Using a two wire lead with socket that plugs into the LCD pin header.
    I kinda figured it was DOA, just hoping that it wasn't lol.

    Have sent off an email to parallax requesting a new part, will have to wait till they get back from holidays.

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  • burtechbdaburtechbda Posts: 1
    edited 2010-01-30 18:33
    computer guy,

    You're not alone, I have the same issue. (pic attached)

    Reco
    _Device Memory_home_user_pictures_IMG00128-20100130-1429.jpg
    640 x 480 - 69K
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