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Hot!Random pixel shift to the left

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2020/07/28 08:07:53 (permalink)

Random pixel shift to the left

Harmony 2.06 w/Graphics Composer and using Low-Cost-Controller
320x240 TFT LCD running 8bpp fed via DMA -> PMP
Everything is working and looking good except for one issue:
There are random lines that are shifted left by a single pixel, they happen randomly, though constantly.  The PMP hold/setup/strobe times are lined up per the display data sheet as are the Pulse-Width and Front/Back Porches.  Would estimate every 7-8th row is shifted but constantly changing which rows are mis-aligned.
Anyone seen something like this or have any ideas?  We may end up putting down an external SSD1963 controller to get past this issue but would prefer to keep the internal LCC solution we have working.

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    Sooper Geeneeus
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    Re: Random pixel shift to the left 2020/08/05 06:52:54 (permalink)
    First, have you verified the hold/setup/strobe times on a scope? Is there much jitter on the pixel-clock with respect to the h/v sync and DE? Do you have flexibility to slow down the pixel clock to see if that affects it? You can change the clock by changing the divisor for PBCLK8, I believe.

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