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Altera_Forum's avatar
Altera_Forum
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18 years ago

same constraint, different compiling time

My system has 360 input signal and need to be constraint as clock.

I use the following two method to create clock: 


method 1:
create_clock -name {FREQMeasure_ChannleIn} -period 10000.000 -waveform { 0.000 5000.000 } }]
method 2:
set FREQMeasure_Total_Channel 360
for {set loop 0} {$loop < $FREQMeasure_Total_Channel} {incr loop} {
	puts "loop is $loop"
	create_clock -name FREQMeasure_ChannleIn_Clk -period 100000.000 FREQMeasure_ChannleIn
}

Compiling elapsed time for method 1 is 50 minutes.

Compiling elapsed time for method 2 is 80 minutes.

the result for two compilation are the same.

Is there anything I should take into account?

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  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    18 years ago

    --- Quote Start ---

    Hi,

    The 360 input signals are unrelated so they won't arrive at the chip at the exact same time. But they never crossing into each other domain.

    So I think the two constraints listed above should result into the same result.

    Am I wrong?

    --- Quote End ---

    You are correct. If each domain is independent in the design you can apply one clock constraint to them all.
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    18 years ago

    By the way, and just to be sure, you keep saying 360 inputs signals, but you mean 360 input signals that are clocks? I've never seen 360 different clocks on a signle board and wanted to make sure that is the situation. (I'm also concerned about how they're all handled, but I think that's been the gist of all the postings so far.) Needless to say, you have a very complicated design.

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    18 years ago

    Hello,

    just want to remind my comment, that I'm not sure, if the said 360 measurement or "clock" signals need constraints at all. It depends on the kind of processing, that is performed with this signals, e. g. frequency counting, intervall measurement, etc. In other words, I doubt if the discussion, beside giving interesting insights in Timequest operation, has an actual object.

    Regards,

    Frank