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Altera_Forum's avatar
Altera_Forum
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14 years ago

Timing Not Being Constrained?

My problem is that my design passes timing closure no matter how I constrain it (well almost). In particular, if I constrain the output timing like this; create_clock -name {real_clock} -perio...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
14 years ago

set_clock_groups is pretty safe as long as you don't use the special syntax of having only one -group. That tells it to cut the clocks in that group from all other clocks in the design without explicitly naming them, so it's an implicit cut. You should merge them:

set_clock_groups -asynchronous

-group {

real_clk

}

-group {

real_clkb

}

-group {

real_clkb

}

This only cuts between clocks in different groups of the same command, but will not cut timing to any clocks not listed.