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Precise Pixel Timing in uOLED-32024-P1 (Picaso 4DGL)

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  • Precise Pixel Timing in uOLED-32024-P1 (Picaso 4DGL)

    Hi,
    I am trying to turn a single pixel on and off for a scientific application, but I am having trouble with the timing. My program (see below) looks for a high input on IO1_PIN and--if the pixel is off--turns the pixel on (and vice versa for turning it off). This mostly works. However, I have checked with a phototransistor and an oscilloscope and the pixel takes anywhere from 0 to 12.6 ms to respond to the input voltage. This delay is not random phase jitter, but slowly changes with time (starting at 12.6ms, decreasing to 0ms, and jumping back to 12.6ms); this prevents me from getting another function generator to phase-lock to the pixel light (unless I slow the frequency way down). Does anyone have some ideas about how to get a better-defined phase which I can phase-lock to an external function generator, or how to get a more instantaneous response to the input voltage?
    Any ideas are welcome.
    Thank you.


    -----------------------------------------------------------------------------------------------
    #platform "uOLED-32024-P1_GFX2"
    #inherit "4DGL_16bitColours.fnc"

    // Turn pixel on and off based on input to DIO

    func main()
    var x,y,ON;

    pin_Set(INPUT,IO1_PIN), 0; // mode=1 sets IO1 to be used as digital input
    x := 450;
    y := 151;
    ON := 0;

    while (1)
    if (pin_Read(IO1_PIN)==1 & ON==0) //if should be on but off
    gfx_PutPixel(x,y,0xFFFF),0;
    ON := 1;
    else if (pin_Read(IO1_PIN)==0 & ON==1) //if should be off but on
    gfx_PutPixel(x,y,BLACK),0;
    ON := 0;
    endif
    wend
    endfunc

  • #2


    I think you are 'seeing' the scaning rate of the oLED

    Not much that can be done about that
    Mark

    Comment


    • #3


      Thanks for the response; I have looked also at the WRITE output (pin 58 on the PICASO chip, also pin 13 on J1 connector), and it shows the same 'jitter' between this WRITE and the pixel light. Can you explain this? Why doesn't the write output correspond directly (with some fixed delay) to the pixel lighting up? Is there another chip on the display itself that changes the timing?

      Comment


      • #4


        I imagine the output pin will come on first and will be followed by the pixel as it wont be turned on until the scanning process next processes that pixel.
        Mark

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