Here the setup check now has one extra clock cycle of the startClock.
Now let’s constraint it for multicycle operation. This is equivalent to specifying `set_multicycle_path 1 -setup -end -from FF1/CP -to FF2/D set_multicycle_path 0 -hold -start -from FF1/CP -to FF2/D` The above figure gives the default setup and hold check edges of a fast-to-slow timing path. `set_multicycle_path 5 -setup -end set_multicycle_path 4 -setup -end`ĬASE2: Fast launch clock and slow capture clock. `set_multicycle_path 3 -setup -end set_multicycle_path 2 -hold -end` Move the hold edge ([ath_multiplier – 1) cycles from the endClock.Į.g. This is the required constraint for a proper timing check. Let’s see what happens if we move the hold edge with respect to the capture clock. Now let’s try setting a hold constraint `set_multi_cycle_path 1 -hold -start` Once you set this, the hold check edge will also move to one clock cycle before the setup check, if you don’t specifically state the hold checking edge. To move this one clock cycle of CLK2, specify `set_multi_cycle_path 2 -setup -end -from FF1/CP -to FF2/D` Here, the red lines show the default setup and hold checking edges without any constraints specified. Here CLK1 and CLK2 are two different frequencies, and multicycle path needs to be set between FF1 & FF2.ĬASE1: Slow launch clock and fast capture clock start/-end options are relevant only for multifrequency paths. (-end is the default) Hold: Regarding to StartClock by Default. Default path_multiplier: Setup 1, Hold 0. end indicates that the multicycle information is relative to the endClock. start indicates that multicycle information is relative to the startClock. `set_multicycle_path -from -to path_multiplier` The SDC command `set_multicycle_path` has an option `-start/-end` that helps in these scenarios. Now let’s explore multicycle paths with two synchronous clock domains of different frequencies. When prompted to save changes you made, click Yes.We have seen set_multicycle_path constraint for timing path within a single clock domain.