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640x3x480 ttl 18bit color lcd display control possible? — Parallax Forums

640x3x480 ttl 18bit color lcd display control possible?

omegatotalomegatotal Posts: 4
edited 2012-06-29 21:39 in Propeller 1
I have a Sharp LQ104V1DG21 TFT-LCD Module http://www.sharpsma.com/webfm_send/1225

And I would like to be able to drive this as a basic touch control pad for some home automation. I dont need full color, or more than a few updates per second, but I do desire to have full resolution.

basically I would like to use the propeller as a display controller for this and also have it read the resistive touch overlay and communicate via serial to another device.

There is a library for arduino and an adafruit display I would like to have similar features so I can write simple start coordinate, end coordinate, fill color, outline color commands via serial




TAGS: ttl 18bit color lcd 640 480 640x480 rgb 640x3x480 640rgb480 tft

Comments

  • RaymanRayman Posts: 14,827
    edited 2012-06-29 06:47
    I'm currently driving a 5" Newhaven TFT and 800x480 using our DVI Graphics shield along with the Touchscreen plugin.
    The DVI Graphics shield has a SSD1963 chip that can drive your display (at least, I think so).
    You would need some kind of breakout for that screens FPC connector and then you can connect it to the DVI Graphics shield...
    This will give you 24-bit color.

    If you just need 6-bit color and no fancy graphics, then you can try what I do for the NH4 and Samsung 4.3" TFTs and use a modified version of the
    regular VGA driver to drive the LCDs. My codes are for 480x272 though and would need some work to adapt to 640x480...
  • omegatotalomegatotal Posts: 4
    edited 2012-06-29 07:04
    well what I have is the raw display ready to mount to an industrial panel, I do have the interface cable that I can chop in half, however I dont want get into purchasing additional controllers to drive this lcd at such a low color and refresh rate.

    also I am assuming I could simply take the 6 bits per pixel and make them into 2 bits per pixel or bits per pixel by grouping in 2x3 or 3x2 for each color to give me the more limited color and save pins/code required, since in my case I don't need lots of colors
  • RaymanRayman Posts: 14,827
    edited 2012-06-29 07:26
    Sounds like you will want to copy what we have for NH4 and the Samsung 4.3" TFT then...
    I don't think you can really slow down the frame rate too much or the screen will flicker...

    Maybe with some simple changes to that code, you can get it working.
  • kwinnkwinn Posts: 8,697
    edited 2012-06-29 07:41
    While you may only need to update the display information a few times per second you will still need to refresh the displayed image about 60 times per second.

    A 640x480 image has 307,200 pixels and needs 76,800 bytes for a 2 bit/4 color image so the prop does not have enough internal memory to store the image as a bit map. You could get around that by using external memory and circuitry, or creating the image from an array of 8x8 pixel blocks.
  • omegatotalomegatotal Posts: 4
    edited 2012-06-29 07:52
    kwinn, do you have any ideas or suggestions as to what I would need for external memory to do so?
    (still fairly new to propeller)

    as to the refreshing of the display, if I add sufficient speed/size ram I assume that the propeller can handle the refresh requirements?
  • RaymanRayman Posts: 14,827
    edited 2012-06-29 08:26
    Using the NH4 approach, you can do the same type of text and graphics that you can do with the standard Propeller VGA driver...
    That refreshes at 60 Hz, so it should be perfect for your display.
  • kwinnkwinn Posts: 8,697
    edited 2012-06-29 21:39
    omegatotal wrote: »
    kwinn, do you have any ideas or suggestions as to what I would need for external memory to do so?
    (still fairly new to propeller)

    as to the refreshing of the display, if I add sufficient speed/size ram I assume that the propeller can handle the refresh requirements?

    First, I have to say that building your own display driver board would be a lot of work and more costly than buying a suitable one such as the NH4.

    For external memory there are several options you could use for 4 color 640 x 480. Static ram is the simplest but requires a lot of address and data lines. Another option might be a serial sram or dynamic ram, but I have not had enough experience with either to be certain they would work.

    If I were to take on the challenge of designing a video board like you are looking for I would probably use one of these "http://www.digikey.ca/scripts/dksearch/dksus.dll" or something similar.
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