SDC constraints

create clock

create_clk  -name  SYSCLK  -period 10 –waveform {0 5}  [get_ports clk]                                    

 (more_about_this_construct)

Setting clock uncertainty

set_clock_uncertainty  2  [get_clocks SYSCLK]                                  (more_about_the_construct)

Setting clock transition

set_clock_transition  -rise  1     [get_clocks SYSCLK]      

set_clock_transition  -fall  1      [get_clocks SYSCLK]      (more_about_the_construct)