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µOLED 160 GMD1 problem

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  • µOLED 160 GMD1 problem

    Hi guys. I am totatly new to this LCD's and i have a problem here.

    I uploaded couple of images with the Graphics Composer onto the MMC card and inserted the Jumper to see if the images were there. Yes the Slideshow was fine.

    Now when i removed it and sent a command to see an image then i gor a square of where the image should be in the correct size and position but instead of the image the was scrambled pixels. I tried to change the Color mode but still got the same thing.

    What could be wrong here?

    I updated to the latest revision the LCD and still the same problem.

    Please help me out here guys.

  • #2

    well if anyone is wondering i found the problem.

    It seems that the latest version of the Graphics Composer has a problem.

    here is what i get in the *.txt file

    Location = 0x200000(2097152)

    but in the command below it says
    Cmd (0) = 40
    Cmd (1) = 49
    Cmd (2) = 0
    Cmd (3) = 0
    Cmd (4) = 28
    Cmd (5) = 28
    Cmd (6) = 10
    Cmd (7) = 0
    Cmd (8) = 10

    where CMD 6,7,8 are 0x0 , 0x10, 0x0

    so am i wrong here and messed up somwhere or am i correct here?


    • #3


      I have found that MOST of the "Cmd" values are usable, but not all. For example, the command to display the image noted in your message would be:
      (0x40, 0x49, 0x0, 0x0, 0x28, 0x28, ox10 ,0x20, 0x0 ,0x0)

      That would display the 40x40 pixel image at 0,0 on the screen using 16 bit color and reading the image from sector 0x200000 (default address for first image loaded by the GC). as you can see, the first 7 commands in the text file are usable directly. The address of the file (the last three parameters of the command) however, needs to come from the "Location=" value at the top. I think the last two "Cmd" values are not intended to represent the load address or to be part of the display command. The Display Image command requires 10 bytes and only 9 bytes are shown in the "Cmd" list.

      I'm not sure why this is so, but it's how I've managed to get things working.

      Use the first 7 bytes from the "Cmd" list (Cmd(0)-Cmd(6)) and get the sector address (3 bytes) of the image you want to display from the Location line.

      Any technology, sufficiently developed, is indistinguishable from magic. A.C. Clark(RIP)

      NEW! Lower prices on all 4D Systems products for 2009 and continuing into 2010!


      • #4

        Tnx steve. I also have another problem with the "Pen Size"

        The LCD doesn't seem to get the command. If i draw a cercle then the command is ok but the Pen Size command doesn't seem to work the way it is described in the manual.

        Any suggestions?


        • #5

          Please check that you have the latest PmmC loaded.


          • #6

            ok, it seems that the problem is elsewhere.

            What should the power be for the LCD ?

            I'm powering it up with a step-up regulator to about 4.2v

            so when i turn it on it replies to all the commands but when it comes to displaying images the LCD restarts.

            If i insert the pin to see the slideshow then everything is displaying fine.

            PS: i have the latest (4) revision installed


            • #7

              From the uOLED-160-GMD1 documentation:

              "Voltage supply from 3.6V to 6.0V, current @ 40mA nominal when using a 5.0V supply source."
              So 4.2V should be fine if the host you're using can source the current requirements of the display. Can you provide a bit more detail on what you mean by "the LCD restarts"? Does it act like a reset (goes to splash screen) or some other behavior?

              Any technology, sufficiently developed, is indistinguishable from magic. A.C. Clark(RIP)

              NEW! Lower prices on all 4D Systems products for 2009 and continuing into 2010!


              • #8

                exactly. it flickers and goes to the splash screen. Or tries to show the first image and restarts.

                If i pump up the juce to 4.6-5v then it's fine.


                • #9

                  The display works fine without a card at the lower voltages. There is approximately 0.5 volt drop from the input voltage to the internal system voltage at the low end of the scale. We have several units here with different brand cards and some even work as low as 3.0Volts input supply where others will only work above 4.0Volts.


                  • #10

                    Mine does not work below 4.5V neither, no µSD card inserted.
                    Check that you provide enough current too, the OLED screen can draw up to 100mA when all pixels are lit up.