====== clock ======

===== - LE TE =====

A for clock-off, B for leading edge, and C for trailing edge events

{{:edastudy:tessent:pasted:20240528-193153.png?nolink}}


===== - 同步时钟 =====
add_clocks 0 shift_clock

===== - 异步时钟 =====
add_clocks REF_CLK -period 20ns

===== - generated时钟 =====
add_clocks PLL_1/pll_clock_0 -reference REF_CLK -freq_multiplier 16 -freq_divider 5


===== - 注意项 =====
要注意async clock 与 sync clock的区别，定义不同。