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Beginner
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AN477 Question

 Hello,  I just  feel strange with AN477 doc below:

https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/an/an477.pdf

page 12

Screenshot from 2020-09-17 17-50-01.png

 why the

      Calculated output maximum delay =  tsu of external register = –0.9 ns

 is not -tsu of external register ? 

 or  = 0.9 ns ?

 

 thanks for your help

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Moderator
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This is because


1) The multicycle assignments are used to create a setup relationship of 0ns and a hold relationship of -1/2*period.

2) The value for set_output_delay -max is now negative due to the 0ns setup relationship set by the multicycle then the setup requirement (max data delay).



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Listening to you is better than reading ten years!!! Thanks。

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Beginner
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Sorry, 

I have thought for a long time, but I still don't understand. Could you describe it in detail? thank you

 

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