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Thread: Confusion

  1. #1
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    Unhappy Graphical and Alphanumerical LCDs

    As i have had no reply to my last post i have been doing some research.

    I have still not found anything on the LCD in question but i have found out something i didn't know.

    Please correct me if i am wrong.

    There are 2 type of LCD screen - Graphical and Alphanumeric?

    The hitatchi chip set which so many of u use converts the data from the computer directly into pre assigned charactor set, but with the graphical type of LCD the charactor set has to be made with the computer.

    Is this correct?

    Bob.

  2. #2
    FLAC
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    I can't answer this question.. but i suggest you start using more descriptive subjects to your post than "confusion" for instance you might try "Graphical and Character LCDs?" or something of that nature...

    Good luck
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  3. #3
    Registered User MP3IAN by Ian Gregory's Avatar
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    There are 2 type of LCD screen - Graphical and Alphanumeric?
    You are quite right Bob. If noone else is to reply, then i will.

    Character or Alphanumeric LCD's are controlled by 'onbaord' chipsets. These are commonly the Hitachi HD44780 chipset whch can be wired directly to your parallel port and by using many different peices of software that are floating around the net, you can easily get a great source for your MP# titles etc.
    These LCD's are commonly made up in the sizes: 2x16, 2x20, 2x40, 4x20, 4x40. (in the form of rowsxcolumns).
    Each character is made up within a seperate grid of (don't qwuote me on this) 5x7 pixels or something like that!

    Graphic LCD's, on the other hand, are a completely different story. They aren't as easy to interface and usually require alot more programming to get them running. Unless you know alot of C or C++ (i do but not for getting LCD's working) then you may as well forget it. There are a few peices of source code floating around but i ahvent been bothered to get one going.
    These are made up of one single matrix (eg. 320x240, in the form pixelheight,pixelwidth). Picture a magna doodle, it is made up of many different segments that i assume holds iron filings. Instead of using seperate matrixes to produce letters it uses the whole matrix to produce words, sentences and graphics etc.

    I have a brand new CCD backlit 320x240 graphic LCD(still has plastic on the screen) that i have never even bothered trying to operate. If anyone would like to shed some light on how to then perhaps you could add your 2 cents and help Bob out a little in choosing an LCD otherwise, i'm up for offers.

    Personally, i would stick to the alphanumeric choice. (easier to use and operate)

    Anyway's, hope this sheds some light on your problem.

    Enjoy, Ian

  4. #4
    FLAC PatO's Avatar
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    Pretty good description Ian, but I think Graphical LCD's are not necessarily as difficult to operate as you think. Matrix Orbital graphical displays have built in character sets that allow you to use them similar to character lcd's. Simply pass a stream of characters to the serial port and *presto*, they are displayed.
    To position the start of text at a certain place on the display, you pass a special control character and the x,y location, followed by the text. Easy as pie.

    The benefit of graphical over alphanumeric, obviously, is that you can draw pictures, specify custom fonts, and display pictures. These are not complicated things as far as programming goes. If you can count squares on a checkerboard, you can write code to display stuff on an lcd.

    My experience is limited to MO displays. They are more or less plug and play through the serial port. No schematics or wiring required. This convenience and simple use of text features come at a cost, but for someone without the desire or time to figure out parallel displays, they work just fine. I use VB to send strings to the serial port (which tends to be easier than c++), but you could even use Batch (.bat) files from the command prompt!
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  5. #5
    Registered User MP3IAN by Ian Gregory's Avatar
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    I have a 320 x 240 graphic LCD that i would like to rig up! Can you tell me how i would go about wiring this to my serial port then?

    details as follows:
    it has Sanyo LC794xx controllers. It is from Data International 32240 ?WN2C2W-H 316-2450
    Pins:
    1-4: D0-D3 Display Data
    5: /DISPOFF Hn Lff
    6: FLM First line market
    7: M Frame reverse signal
    8: LP Data latch
    9: CP Data shift
    10: VCC power supply for logic circuit (+)
    11: VSS Ground
    12: VLCD Power for LCD (-)
    13: VADJ Operating voltage LCD driving
    14: FGND front panel ground

    I have a feeling i may need a controller? Any ideas?

    Where can i get an appropriate backilght inverter for this?

    Thanks! (I'm excited!)

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