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Participant
Participant
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Registered: ‎06-04-2020

clocks are related but found no common period

TIMING #1 Critical Warning The clocks FOUT4_clk_wiz_0 and FOUT1PH0_clk_wiz_0 are found related (timed together) but have no common (expandable) period

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Moderator
Moderator
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Registered: ‎03-16-2017

@Harish_Algat  This warning says : 

The two clocks reported are considered related and timed as synchronous by default. However, the timing engine was unable to determine a common period after expanding the waveform of both clocks over 1000 cycles. In such a case, the worst setup relationship over these 1000 cycles is used for timing analysis. However, the timing engine cannot ensure this is the most pessimistic case. This typically occurs with clocks with an odd fractional period ratio.

Resolution:
As the waveforms do not allow safe timing analysis between the two clocks, it is recommended to treat these clocks as asynchronous. Therefore, the paths between the two clock domains should be covered by a timing exception (such as set_max_delay -datapath_only, set_false_path, or set_clock_groups).

Regarding all other methodology warnings, you can check UG906 Appendix A. https://www.xilinx.com/support/documentation/sw_manuals/xilinx2020_1/ug906-vivado-design-analysis.pdf

 

 

Regards,
hemangd

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