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    latency of the dsync output

    Do we expect output of dsync to get the stable input after 2 or 3 destination clks? Are there any other practical cases we should consider?

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    Re: latency of the dsync output

    No idea what you are talking about... context?
    Really, I am not Sam.



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    Re: latency of the dsync output

    Quote Originally Posted by ThisIsNotSam View Post
    No idea what you are talking about... context?
    After you see a change on d input of dsync, how many destination clk cycles does it take to see a change on the output?



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    Re: latency of the dsync output

    We don't know what is "dsync"!
    Please frame your question properly with a proper background explanation or reference (if needed).
    .....yes, I do this for fun!



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    Re: latency of the dsync output

    Quote Originally Posted by dpaul View Post
    We don't know what is "dsync"!
    Please frame your question properly with a proper background explanation or reference (if needed).
    back to back flops (synchronizer) on clk1 with async input at d pin. When async input changes, you may see output change after 2-3 clks. Is this correct?



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    Re: latency of the dsync output

    Quote Originally Posted by stanford View Post
    back to back flops (synchronizer) on clk1 with async input at d pin. When async input changes, you may see output change after 2-3 clks. Is this correct?
    Who knows. Check the documentation of the library. A synchronizer can have any number of stages...
    Really, I am not Sam.



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    Re: latency of the dsync output

    Quote Originally Posted by stanford View Post
    back to back flops (synchronizer)
    For 2 flops as synch



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    Re: latency of the dsync output

    Why don't you sketch a timing diagram?



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    Re: latency of the dsync output

    Quote Originally Posted by FvM View Post
    Why don't you sketch a timing diagram?

    async input
    _________|----------------------------------------

    clk
    _________|------|____|------|____|------|____|

    case 1
    ______________________|----------------------

    case 2
    ________________________________|-------



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    Re: latency of the dsync output

    For a double sync you should ideally see the output after 2 destination clocks. However, when you move from one clock domain to other, synchornizers make sure that probability of metastability will be reduced to almost 0, but they do not guarantee that data will be sampled in 2 clock cycles. Data may take more time than that.

    Thanks,
    Abhishek



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