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    synthesis question about generated clocks

    Hi, if for example i have two clocks then they are connected to a mutiplexer, should i declare the output as a generated clock?

    •   Alt4th September 2017, 03:30

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    Re: synthesis question about generated clocks

    not needed. just make different sdcs and use set_case_analysis for each clock mode
    Really, I am not Sam.


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    •   Alt4th September 2017, 16:05

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    Re: synthesis question about generated clocks

    Quote Originally Posted by ThisIsNotSam View Post
    not needed. just make different sdcs and use set_case_analysis for each clock mode
    If you do nothing wouldn't dc_compiler time the corresponding registers with both clocks?



    •   Alt14th September 2017, 18:19

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    Re: synthesis question about generated clocks

    Quote Originally Posted by TonyLS View Post
    If you do nothing wouldn't dc_compiler time the corresponding registers with both clocks?
    no, it will do either one or the other
    Really, I am not Sam.



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    Re: synthesis question about generated clocks

    If you set in DC variable timing_enable_multiple_clocks_per_reg to true, the tool will time the registers with both clocks. So, it will save runtime - you have timing for both clocks in on session (do not need to switch set_case_analysis). But, you may have timing from one clock to the other - call them asynchronous or set false path between them. It's up to you.



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