Completely Stumped

Discussion in 'Programmer's Corner' started by Mr.Gadget, Feb 28, 2013.

  1. Mr.Gadget

    Thread Starter New Member

    Nov 25, 2012
    I have spent months trying to figure out PIC's and programming and simply can't do it. My problem is that I have built 2 PIC projects using 16f54 and 16f628 but none work with modern 1X16 displays. The designers no longer offer support but their projects are still all over the net. All I get are 8 solid blocks on the left side on displays.Believe to have traced the problem to different initialization routines in new displays and I have tried to pick the programs apart, but I simply can not do it. Call me stupid I guess. If anyoune can help me update the program to work with modern 1x16's I can supply the original HEX and ASM codes as well as Data sheet on display with init. routine. ANY HELP would be a great help.
    P.S. plugged a 2x16 display with an hd44780 controller into the 16f54 and that works as a one line. Odd, huh?
  2. bance


    Aug 11, 2012
    You're not likely to get much help, with that non-descript title...

    Post the ASM code and datasheet, I'll try and look at it, maybe I can help. But I warn you I'm no expert!!!

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  3. davebee

    Well-Known Member

    Oct 22, 2008
    Do the LCDs have biasing adjustments? I have had that kind of problem when my LCDs were biased to display too darkly; they were displaying characters but the LCD itself was overbiased.

    See if the LCDs have a little adjustment potentiometer and try changing it; it should make the LCD go lighter and darker, and see if your characters appear at the midrange setting.
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  4. MrChips


    Oct 2, 2009
    Completely Stumped:

    Here is a better title: Problem interfacing PIC16F54 with LCD.

    So the PIC16F54 works with a a 2x16 display. That is a big step forward.
    So this says that the software and interface to the 2x16 LCD is working.
    Next step is you have to provide the program code and the model of the 1x16 LCD and the datasheet.
    Show us your connections from the PIC to the LCD.

    Do you have a 0.1μF capacitor across VDD and VSS on the LCD?
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  5. spinnaker

    AAC Fanatic!

    Oct 29, 2009
    What have you done to troubleshoot your code and device? The best thing to do is take it step by step. Start your debugger, step through the code and use a scope, logic probe etc. to test to see if it is doing what you expect.
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  6. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    No, that is not odd at all, in fact it is a major clue!

    These displays can be pesky things to get initialized properly, least you get the dreaded black squares. By getting a display to actually work means you have good code for an HD44780, and the proper electrical connections too.

    I must ask: do you have the contrast pot in the circuit? I have several LCD displays, and one of them does not need the pot, the others do. So if you don't have that part get one.

    So once you have that pot installed, if the 1x16 still doesn't work, triple check the connections, and if all are good, I would suspect it is a bad display.
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