[GSoC Daily Log]: Trails & errors

Friday, 20th June 2014:

  • Removing the DATACK TIMESPEC constraint seems to have removed the frame losses/screen going blank. Consistency: Good. No frame dropping!
  • Adding back DATACK TIMESPEC but now, mentioning period in ‘time’ as ‘ns’ for both TNM_DATACK and TNM_PCLK. Result: Almost same as before. But frame drops. Also I think *slightly* more flickering
  • Removing back the TNM_DATACK but retaining TNM_CLK with 15.384 ns as PERIOD. Result: No frame drop. Flickering same as in first case.
  • Now removing all the timespec constraints. Result: 1 or 2 frame drops. No noticeable performance improvement. Putting them back (except the TNM_DATACK)
  • [Day]
  • Testing: generating HDMI with only pixel clock, others logically generated.
    • With Jahanzeb’s Test Pattern: Still shaking & Frame drops. That means, clock is not stable.
    • With my dynamic test pattern: Still shaking & Frame losses.
  • Now, testing with inbuilt clock, dynamic pattern. Result: Obviously perfect image without any frame loss. So, One culprit is caught: Unstable pixel clock (DATACK)
  • Tried Oversampling: Didn’t work (ie with my implementation which may be wrong)
  • Narrowed down the issue to: Async_edge detected HSYNC/VSYNC vs proper synchronised edge detected HSYNC/VSYNC...also pixel clock is unstable

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