Every timing result depends on the clocks, so clock definition is the first constraint you write and the first you audit. This topic covers how a clock is created, how its waveform and edge cases work, how uncertainty models jitter and margin, and the difference between source and network latency.
Lesson | After it you can... |
|---|---|
Write a correct clock definition and say what it implies. | |
Define non-50% duty cycles and offset clocks. | |
Choose and apply setup and hold uncertainty. | |
Say which latency applies to which clock model. |
The conceptual side of clocks in timing is in Clocks in Timing Analysis; this topic is the constraint syntax and its meaning.
create_clock on the port or pin. Without it flops have no clock, their endpoints are unconstrained, and nothing is checked.