LCD Display Compatibility

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  • WHaThEFLuX
    Badcaps Veteran
    • Feb 2015
    • 277
    • USA

    #1

    LCD Display Compatibility

    Hello All,

    I'm once again having trouble finding a replacement display for one of my projects. I've replaced the original display (http://pdf.datasheet.netdna-cdn.com/627030/DV-16230.pdf)

    with this display which I was certain would be compatible(http://www.mouser.com/ds/2/427/37297-239974.pdf)

    The drivers seem to be identical, however after soldering the replacement display onto the main board I'm greeted with a bunch of dollar signs ($) and other unusable gibberish.

    My questions are:

    1. Are the displays incompatible because the display character address codes are different?(I can't seem to find the address code for the original display)

    2. Is the replacement display actually compatible but needs to be programmed to interpret the data correctly?

    3. Are there any other displays that would be a direct replacement for the original?

    As always, I'd be forever grateful if anyone could point me in the right direction!
    Last edited by WHaThEFLuX; 01-26-2016, 12:34 PM.
    "You can only learn so much doing simple recapping and fixes. Ideally you want a really hard one to fix where you end up with a lot of dead ends and frustration. Then, and only then, do you learn how things really work."

    -retiredcaps
  • WHaThEFLuX
    Badcaps Veteran
    • Feb 2015
    • 277
    • USA

    #2
    Re: LCD Display Compatibility

    Here is another display I was considering: http://www.mouser.com/ds/2/244/LCM-S...%20C-96604.pdf
    "You can only learn so much doing simple recapping and fixes. Ideally you want a really hard one to fix where you end up with a lot of dead ends and frustration. Then, and only then, do you learn how things really work."

    -retiredcaps

    Comment

    • eccerr0r
      Solder Sloth
      • Nov 2012
      • 8682
      • USA

      #3
      Re: LCD Display Compatibility

      You should check if these are all HD44780-compatible. A lot of these 16x2 LCD displays use this standard, and as far as I can tell they are interchangeable for the most part. You could even swap a 20x2 or 20x4 HD44780 and it'd just use the top left without code changes... but that'd be a waste...

      Comment

      • WHaThEFLuX
        Badcaps Veteran
        • Feb 2015
        • 277
        • USA

        #4
        Re: LCD Display Compatibility

        Hmm I didn't see that on the datasheet, would you know how I would go about finding that out?
        "You can only learn so much doing simple recapping and fixes. Ideally you want a really hard one to fix where you end up with a lot of dead ends and frustration. Then, and only then, do you learn how things really work."

        -retiredcaps

        Comment

        • stj
          Great Sage 齊天大聖
          • Dec 2009
          • 30953
          • Albion

          #5
          Re: LCD Display Compatibility

          not enough data,
          the first sheet says blah or compatable controller - not very specific.

          the original hitachi interface can run in 4 or 8bit mode and has a line that says it's ready/busy
          i'v seen people ignore the last bit and use fixed delays to drive displays - the problem may be the design of the thing driving it.

          Comment

          • WHaThEFLuX
            Badcaps Veteran
            • Feb 2015
            • 277
            • USA

            #6
            Re: LCD Display Compatibility

            stj, thanks for jumping in!

            Found a more in depth datasheet, maybe this will help:
            http://www.platan.ru/pdf/datasheets/...n/DV-16230.pdf

            I just need to find a suitable replacement. I still can't understand why the vishay display didn't work, everything matched up, what am I missing?
            Last edited by WHaThEFLuX; 01-26-2016, 11:43 PM.
            "You can only learn so much doing simple recapping and fixes. Ideally you want a really hard one to fix where you end up with a lot of dead ends and frustration. Then, and only then, do you learn how things really work."

            -retiredcaps

            Comment

            • stj
              Great Sage 齊天大聖
              • Dec 2009
              • 30953
              • Albion

              #7
              Re: LCD Display Compatibility

              maybe it's faulty - try it in something else.
              what's wrong with the original?

              Comment

              • WHaThEFLuX
                Badcaps Veteran
                • Feb 2015
                • 277
                • USA

                #8
                Re: LCD Display Compatibility

                Originally posted by stj
                maybe it's faulty - try it in something else.
                what's wrong with the original?
                Half of the characters are missing in the middle of the display.
                "You can only learn so much doing simple recapping and fixes. Ideally you want a really hard one to fix where you end up with a lot of dead ends and frustration. Then, and only then, do you learn how things really work."

                -retiredcaps

                Comment

                • eccerr0r
                  Solder Sloth
                  • Nov 2012
                  • 8682
                  • USA

                  #9
                  Re: LCD Display Compatibility

                  The first PDF says KS-0066U and supposedly https://www.youtube.com/watch?v=j6XEDA62zzE implies it is HD44780 compatible. Your second display explicitly says it's also KS-0066 so theoretically they should be compatible.

                  Perhaps there are some bugs with the KS-0066 that timing is slightly off. Unfortunately I've never worked with KS-0066's yet, not sure of their bugs. I've only worked with the original HD44780 LCDs which seems to work to spec. I'd imagine the no-readback write-only method should work no matter what, but the faster read-busy method might be very timing sensitive and may be incompatible between controllers...

                  Actually scratch that, the write-only method might also require some timing hacks but once again I haven't tried non HD44780's so I don't know except that timing on write-only is pretty crappy...
                  Last edited by eccerr0r; 01-28-2016, 02:19 AM.

                  Comment

                  • fzabkar
                    Badcaps Veteran
                    • Mar 2009
                    • 772
                    • Australia

                    #10
                    Re: LCD Display Compatibility

                    I would compare the displayed characters with the expected characters and then look them up in the font table on page 20 of the datasheet. For example, if spaces (20h) are consistently displayed as dollar signs (24h), then that would point to a problem with a particular data bit (2).

                    Comment

                    • stj
                      Great Sage 齊天大聖
                      • Dec 2009
                      • 30953
                      • Albion

                      #11
                      Re: LCD Display Compatibility

                      maybe it needs some pullup (or down) resistors.

                      any info on what's driving the display?

                      Comment

                      • WHaThEFLuX
                        Badcaps Veteran
                        • Feb 2015
                        • 277
                        • USA

                        #12
                        Re: LCD Display Compatibility

                        Originally posted by stj
                        maybe it needs some pullup (or down) resistors.

                        any info on what's driving the display?
                        I believe it's a Temic IP-80C51
                        "You can only learn so much doing simple recapping and fixes. Ideally you want a really hard one to fix where you end up with a lot of dead ends and frustration. Then, and only then, do you learn how things really work."

                        -retiredcaps

                        Comment

                        • WHaThEFLuX
                          Badcaps Veteran
                          • Feb 2015
                          • 277
                          • USA

                          #13
                          Re: LCD Display Compatibility

                          This is the most comprehensive document I could find on the Temic 80C51, if anyone's up for a good read check it out: http://www.keil.com/dd/docs/datashts/atmel/c51_hd.pdf
                          "You can only learn so much doing simple recapping and fixes. Ideally you want a really hard one to fix where you end up with a lot of dead ends and frustration. Then, and only then, do you learn how things really work."

                          -retiredcaps

                          Comment

                          • stj
                            Great Sage 齊天大聖
                            • Dec 2009
                            • 30953
                            • Albion

                            #14
                            Re: LCD Display Compatibility

                            do you have a scope or logic-probe?

                            Comment

                            • fzabkar
                              Badcaps Veteran
                              • Mar 2009
                              • 772
                              • Australia

                              #15
                              Re: LCD Display Compatibility

                              The KS0066 is a Samsung part. Samsung provides for custom font ROMs.

                              (Samsung KS0066U)
                              (Samsung KS0066U)

                              (Samsung KS0066Fxx)

                              The following URL suggests that the KS0066 is electrically compatible with displays based on ST7066U, HD44780, and SED1278 controllers:

                              http://www.abcelectronique.com/compo...-number=ST7065 (Sitronix ST7066U = KS-0066, HD44780, SED1278)
                              http://www.abcelectronique.com/compo...s_lcds_013.php

                              Is it possible that the OP's application is using an electrically compatible display with a non-standard character generator ROM?

                              Comment

                              • stj
                                Great Sage 齊天大聖
                                • Dec 2009
                                • 30953
                                • Albion

                                #16
                                Re: LCD Display Compatibility

                                unlikely.

                                Comment

                                • WHaThEFLuX
                                  Badcaps Veteran
                                  • Feb 2015
                                  • 277
                                  • USA

                                  #17
                                  Re: LCD Display Compatibility

                                  Is it even possible to determine what kind of character generator ROM a display uses? I found a display with the same pin locations as the original that uses the ST7066U, maybe this one will work?

                                  http://www.mouser.com/ds/2/291/NHD-0...-YBW-29044.pdf
                                  "You can only learn so much doing simple recapping and fixes. Ideally you want a really hard one to fix where you end up with a lot of dead ends and frustration. Then, and only then, do you learn how things really work."

                                  -retiredcaps

                                  Comment

                                  • stj
                                    Great Sage 齊天大聖
                                    • Dec 2009
                                    • 30953
                                    • Albion

                                    #18
                                    Re: LCD Display Compatibility

                                    character rom can just be diplayed and scrolled through

                                    Comment

                                    • WHaThEFLuX
                                      Badcaps Veteran
                                      • Feb 2015
                                      • 277
                                      • USA

                                      #19
                                      Re: LCD Display Compatibility

                                      The plot thickens...


                                      I was able to get my hands on a working board + display, so I fiddled around with it and here's what I learned:

                                      1. Removing the functioning display and putting it in my original board resulted in a blank backlit screen.

                                      2. Placing both of the displays I ordered in the "working" board resulted in a backlit screen with blocks displayed in all 16 character spaces in the top row.

                                      3. Placing the original "non working" display in the "working" board resulted in a blank screen as well.

                                      So from all of this disappointment I've come to the conclusion that both the original board and display are faulty, and neither of the boards I ordered are suitable replacements.

                                      The question I now have is, what could be wrong with the board?



                                      I checked the components on the board and they all seem to be within spec, is it possible the controller failed?
                                      "You can only learn so much doing simple recapping and fixes. Ideally you want a really hard one to fix where you end up with a lot of dead ends and frustration. Then, and only then, do you learn how things really work."

                                      -retiredcaps

                                      Comment

                                      • fzabkar
                                        Badcaps Veteran
                                        • Mar 2009
                                        • 772
                                        • Australia

                                        #20
                                        Re: LCD Display Compatibility

                                        Check that +5V is being output from the LM2575-5.0 (U5).

                                        Check that the uC (U1) is not being held in the reset state by the DS1232.

                                        Check that the crystal X1 is oscillating.

                                        Confirm that the voltages on the pins of the Sipex RS485 transceiver look OK.

                                        Comment

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