对具有不寻常时钟波形的信号进行约束,这些约束无法通过create_clock命令轻松指定 总线skew的约束 异步preset和clear输入引脚之间的recovery和removal约束 Data Check Examples 以下示例显示了具有非连续约束的cell: 该单元有两个数据输入,D1 和 D2。D2 的上升沿是可用来锁存 D1 处数据的有效沿。引脚 D1 称为constrai...
Ogawa, "Bucket spreading parallel hash: A new, robust, parallel hash join method for data skew in the super database computer (SDC)," Proc. 16th Int'l Conf: VLDB, pp. 210.221, Brisbane, Aug. 1990.M. Kitwregawa, and Y. Ogawa, "Bucket spreading parallel hash: A new, robust, ...
set_data_check 通常用于信号间的skew 约束,比如一些高速接口相关信号间的约束。摘一段: Data checks are normally applied where there is a specific requirement of skew (either minimum of maximum) or race condition (where the order of arrival of two signals can affect output and the intention is to...
set_input_delay -max 5 -clock CLKB [get_ports data_in] set_input_delay -min 2 -clock CLKB [get_ports data_in] 仅考虑上面的4条约束语句,对于EDA工具而言,CLKA与CLKB都是频率为100m,相位为0的时钟,只是CLKA接到了内部的寄存器当中,而CLKB只是作为输入IO的参考时钟。甚至set_input_delay 中的CL...
设置时钟的Skew and jitter #Intraclock Uncertainty set_clock_uncertainty0.5[get_clocksC1]set_clock_uncertainty-setup0.5[get_clocksC2]set_clock_uncertainty-hold0.2[get_clocksC2] #Clock uncertainty from C1 to C2 for setup and hold set_clock_uncertainty-from C1-to C2-setup0.5set_clock_uncertainty-fr...
set_output_delay -max [expr 0.7 * apb_clk] -clock apb_clk [get_ports apb_prdata] 为什么要设置70%?因为input delay是约束芯片外部的delay 情况,也就是外部约束70%,内部剩余30%的余量,因为外部的情况并不太清楚,所以估计的悲观一些,output delay原因同理。如果估计的过于乐观,那么如果都是这么设置的有可...
我在设置sdc约束的时候,是对每级逻辑均设置了max delay的,举个栗子。 我设置了get_ports input到In0的max delay。然后又设置了get_pins logic1/o到In1的max delay,那么就存在一个问题,即logic1/o处在input到In0之间,这个在STA中是不允许的。
Timing Constraint 是关键部分,要清楚每个clock 定义对应的电路结构,要清楚所有clock 之间的关系, 要能根据clock 的定义大致抽出clock 结构,要明确uncertainty 需要覆盖哪些因素,要能根据当前flow 调整对应的过约策略,要明确设计中有哪些combinational 的cell 需要做gating check, 要明确哪些逻辑需要做data check, 要明确...
Making source synchronous constraining from FPGA to ASIC and ASIC to FPGA separately might be not enough if the paths on PCB/ASIC are not well balanced (so that data doesn't come in the same moment when clock changes or there is some clock skew/slew rate problem). So we can add ...
Making source synchronous constraining from FPGA to ASIC and ASIC to FPGA separately might be not enough if the paths on PCB/ASIC are not well balanced (so that data doesn't come in the same moment when clock changes or there is some clock skew/slew rate problem). So we can add ...