Not every crossing needs a synchroniser. A signal that provably does not change while it is used needs no settling time, because there is nothing to settle. Such quasi-static signals are the cheapest crossings in a design, and also the most lied about: “it never changes” said without proof is how torn configuration reaches silicon.
Lesson | After it you can... |
|---|---|
Design signals so they are provably static in a mode, with sequencing rules. | |
State the stable-before-use proof obligation and assert it. | |
Communicate quasi-static intent to the checks without blanket waivers. | |
Change configuration while running through safe sequencing patterns. |
Because quasi-static treatment is an optimisation on top of correct crossings: partition first, synchronise properly, document the interfaces, and only then replace synchronisers with proven stability where the saving is worth the proof.