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Converting from old to new style LCD display — Parallax Forums

Converting from old to new style LCD display

sunruhsunruh Posts: 11
edited 2005-05-19 21:13 in General Discussion
I have assembly code I have written·for the·old 2x15 serial LCD, #27910.· Recently I had to replace with the newer LCD.· I converted over by changing the wiring and removing the 254 directives.· I have been working on this for over a·day now and still can't get it to display correctly.· The only character it displays correctly is a capitol U, which is hex 55.· With the start bit 1 and the stop bit 0 that is a continous stream of alternate 1's and 0's, so that it can start at any 1 and read the U.· All other characters produce unpredictable results.· I have also tried using the example with the SXB basic code, and it does not work properly either.· Has anyone had experiance converting over in assembly?· On the old display there was about a +/- 5% forgiveness in the baud rate.· Is this one just much closer tolorances?

Stan

Comments

  • BeanBean Posts: 8,129
    edited 2005-05-17 16:48
    What are you using to clock the SX ?
    Can you post your code ?
    Bean.

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    "SX-Video·Module" Now available from Parallax for only $28.95 http://www.parallax.com/detail.asp?product_id=30012


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    ·
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-05-17 16:52
    Stan,

    ·· Please attach your code to your message so that we may have a look at how you're doing things.· Perhaps that will help.· The only real differences in the modules is the connector for power and data, as well as the commands used to control the display.· The Seetron displays used 254 to preceed commands.· While this is not used on our module, the commands themselves are different as well (Please see the documentation for the LCD Module).

    ·· There is one other possibility you can check.· Please be sure you're setting the correct baud rate using the two switches on the back.· But don't necessarily go by the marking on the blue switch cover itself, please confirm based on what's on the silk-screen for on/off position.· I hope this helps.

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • sunruhsunruh Posts: 11
    edited 2005-05-17 18:09
    Bean, I am using a timeing routine I wrote. I have tested it for 9600 baud, and it's pretty close.
    Chris, I have the baud rate set to 9600 on the display, according to the silk screen. I know the test screen works good when both switches are off. I guess I could try switching the two switches in case the 1 and 2 labels are wrong.

    Shall I just paste my code in a message screen, or is there a way to attach the file to a post?

    Stan Unruh
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-05-17 18:15
    Stan,

    ·· If the "Test" position works correctly as per the settings, then everything should be okay.· I was just making sure you didn't have an upside down switch or something, causing incorrect baud rate settings.· As for code, post it as an attachment please.· This way it can be loaded right into the editor software.



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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • sunruhsunruh Posts: 11
    edited 2005-05-17 18:24
    We'll see if this works.· File should be attached.

    Stan
    SRC
    SRC
    testLCD.SRC
    4K
  • sunruhsunruh Posts: 11
    edited 2005-05-17 21:50
    Never mind, guys, I gave up and ordered the old style from Scott Edwards. Thanks for your help!

    Stan Unruh
    Dir R & D
    Mainline Holographics
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-05-17 21:55
    Stan,

    ·· I'm sorry we didn't get it figured out in time for you.· I was working on trying it here to see what is happening.· I suspect it's a lax timing issue.· Well, Take Care, and good luck on your project!

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • sunruhsunruh Posts: 11
    edited 2005-05-17 22:05
    Chris,

    Thanks so much for your efforts. I finally went back to an old style LCD and confirmed my code was working correctly. I then put the new style back in, and after rewiring and taking out the 254 directives, I got just garbage on the screen. It was very odd though, when I put out a U (hex 55) I got the correct character. For a hex 57 I got the T, which should be hex 54, and with hex 59 I got S (should be hex 53), and so on down the line. So there is definetly something odd going on there. I tried running the example SXB serout code and got all [noparse][[/noparse] characters on the screen. I'm through, but in case you want to look into it for future references, just thought I would describe some of my findings.

    Stan
  • Tom-Matrix OrbitalTom-Matrix Orbital Posts: 38
    edited 2005-05-17 22:25
    Stan,

    Have you ever tried Matrix Orbital displays?
  • sunruhsunruh Posts: 11
    edited 2005-05-18 12:15
    Tom

    No, I have not. I might look into those next time.
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-05-19 19:59
    Stan,

    ·· For future reference, the Seetron LCD was using INVERTED Baud mode.· The LCD Module we have uses TRUE Baud mode.· So that was your issue.


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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • sunruhsunruh Posts: 11
    edited 2005-05-19 20:03
    Chris,

    I wondered about that when I saw the correct display of U, so I inverted each of the bits sent, including the start and stop bits, but still got no results. Maybe the start and stop should not have been inverted? Or maybe I just didn't do it right. I've still got two of those displays and may use them sometime. Thanks for the info.

    Stan
  • BeanBean Posts: 8,129
    edited 2005-05-19 21:13
    Yes to need to invert EVERYTHING including the start and stop bits. Not just the data bits.
    Bean.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    "SX-Video·Module" Now available from Parallax for only $28.95 http://www.parallax.com/detail.asp?product_id=30012


    Product web site: www.sxvm.com

    "It's not getting what you want, it's wanting what you've got."
    ·
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