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How to write sdc for pre/post CTS ?

yamakazu

I want to set different clock uncertainity values in the same sdc file for both pre and post CTS modes. Can I do that ? The following sdc didn't work. How to do that ?

if {[getAnalysisMode -clockPropagation -quiet] == "forcedIdeal"} {
    set jit_add 0.2
} else {
    set jit_add 0
}
set_clock_uncertainty [expr 0.200+${jit_add}] \
  -from [get_clocks {my_clk}] -to [get_clocks {my_clk}]

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  • yamakazu

    Hi Khandaker,

    I am confused. My original question is to ask how to identify pre/post CTS in the SDC. I have some more questions.

    1. If we need the set_propagated_clock command to propagate clock (it means post-CTS), does it mean that the SDC (includes set_propagated_clock) is for post-CTS usage but not for pre-CTS?

    2. If we use this command for pre-CTS netlist, is clock propagation really done ?

    3. Where should this command be ? (Before or after the following code ?)

    if {[get_property [get_clocks $my_clock] is_propagated_clock]] == "true"} {
                set_clock_uncertainty [expr .......] $my_clock
    } else {
                set_clock_uncertainty [expr .......] $my_clock
    }

Reply
  • yamakazu

    Hi Khandaker,

    I am confused. My original question is to ask how to identify pre/post CTS in the SDC. I have some more questions.

    1. If we need the set_propagated_clock command to propagate clock (it means post-CTS), does it mean that the SDC (includes set_propagated_clock) is for post-CTS usage but not for pre-CTS?

    2. If we use this command for pre-CTS netlist, is clock propagation really done ?

    3. Where should this command be ? (Before or after the following code ?)

    if {[get_property [get_clocks $my_clock] is_propagated_clock]] == "true"} {
                set_clock_uncertainty [expr .......] $my_clock
    } else {
                set_clock_uncertainty [expr .......] $my_clock
    }

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