AR# 38546

Description

Why are the number of lines per frame being incorrectly detected?

This happens in the following situations:

• If the vertical sync (vsync) and the horizontal sync (hsync) do not change on the same cycle, then the timing controller detector could incorrectly detect one extra line per frame (for example if the vertical sync changes one or more clock cycles before the horizontal sync changes).
   
  
• If the vertical blank (vblank) and the horizontal blank (vblank) changes do not change on the same cycle, then the timing controller detector could incorrectly detect one extra line per frame (for example if the vertical blank change one or more clock cycles before he horizontal sync changes).

Typically, these changes should happen at the same cycle, but there could be cases where they are not aligned.

Solution

This is a known issue that is to be addressed in the next release of the Video Timing Controller IP.

This problem has been fixed in the Video Timing Controller 2.1 Rev2 patch.

To obtain the patch, see (Xilinx Answer 35096)

For a detailed list of LogiCORE IP Video Timing Controller Release Notes and Known Issues, see (Xilinx Answer 32754)

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