一、path_group相关 (1)report_path_group (2)group_path (3)同步时钟间的path计算 (4)clock_latency 二、多时钟周期设置 (5)multicycle_path 设置 三、clock_groups设置 (6)set_clock_groups 设置时钟关系为异步 (7)logically exclusive 与 physically exclusive 经过上一篇用chisel写了个简单的跨时钟rtl后,...
外部器件的频率和FPGA内部的频率不同 creat_clock -name sysclk -period 10 [get_portsclkin] creat_clock -name vclk -period 5 set_input_delay 6 -clock sysclk [get_ports dina] set_input_delay 6 -clock vclk [get_ports dinb] 注意vclk的时钟频率和internal clock的时钟频率相同 虽为同一个时钟...
设置端口或者pin上时钟的输入或输出时延值. 3.2 Exceptions 添加时序例外路径约束可减少编译时间,降低约束的调试难度以及阻止工具优化掉一些需要的信号,常用的时序例外约束Set minimum Delay/Set maximum Delay,Set Multicycle Path,Set False Path. 3.2.1 Set minimum Delay/Set maximum Delay 设置某些路径的最大时延或...
(1)report_path_group 这是用于报告path_group的指令。在dc中，如果没有sdc约束时钟，所有path都会被放置在名为default的path_group中。如果sdc中约束了时钟，不同时钟的path会被分配到不同的path_group中。我们可以先简单地查看跨时钟域的path。例如，根据rtl，keepvalue[0]在快时钟域中准备向慢时钟...
In an integrated circuit, a system and method of programmably controlling the delay between a second clock signal with respect to a first clock signal after fabricating the integrated circuit. Prior to fabrication, a programmable delay group is formed and will be included in the integrated circuit...
Zero skew island: The island refers to a group of registers with equal delays. 2. Target delays:tcdk1, where kα≤ r and δk1…δkα are explicitly specified clock signal delay constants. 3. Target skews: sj1 = σj1…, sjβ = σjβ, where jβ < nb and σj1…σjβ are explici...
Delay locked loop and its control method for correcting a duty ratio of a clock signal A delay locked loop (DLL) capable of correcting a duty ratio including: a clock buffer for receiving an external clock signal and an inverted external clock signal to generate a rising edge clock signal; ...
Using the CLOCK_DELAY_GROUP Constraint on Several Clock Nets Using the CLOCK_DEDICATED_ROUTE Constraint Using the CLOCK_ROUTE_GUIDE Constraint Clocking Topology Recommendations MBUFG Primitives Parallel Clock Buffers Cascaded Clock Buffers Clock Multiplexing ...
Our concern with using set_clock_groups is that one bit in a group of signals will end up having a much longer delay than the other signals in the group, between two registers clocked with different clocks. (e.g., several latch clock cycles more) My thoughts is that even...
(1)减小扇出Fanout,扇出指模块直接调用的下级模块的个数,如果这个数值过大的话,在FPGA直接表现为Net Delay较大,不利于时序收敛。减小扇出的方法有:①寄存器复制,寄存器复制是解决高扇出问题最常用的方法之一,通过复制几个相同的寄存器来分担由原先一个寄存器驱动所有模块的任务,继而达到减小扇出的目的。②Max_Fanout...