Hello, I just feel strange with AN477 doc below:
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
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).