Description The set_false_path command identifies specific timing paths as being false. The false timing paths are paths that do not propagate logic level changes. This constraint removes timing requirements on these false paths so that they are not considered during the timing analysis. The path ...
因为reg到reg之间的设定,reg1/Q到reg2/D,必然会打断reg1的CP到Q的timing arc ,从而影响到了同步paths check,此时可以准备两套sdc,分别对timing 进行check 4)set_max_delay命令优先级 set_clock_group之后,对于异步时钟组的时钟,设置从reg1的cp端口到reg2的D端口,这种合法的起始点,是不能生效的,但是从reg1...
1、异步fifo中格雷码约束 为了保证异步fifo的功能和性能保证,需要在综合约束文件sdc中,约束异步FIFO格雷码的最大延时。约束如图所示:从格雷码寄存器的时钟端口--->到3级同步器的输入端口的最大延时。写地址waddr和读地址raddr格雷码同步都需要设置set_max_delay。此处set_max_delay是为了保证源端信号到达目的端被采样...
指定禁止路径的起点(时钟、端口、接脚或单元)。如果你没有指定一个from_list,所有终点在to_list的路径都被设为禁止。from_list可以包含时钟、接脚或端口。如果你指定一个时钟,所有起点与指定时钟相关的路径都会有影响。如果你指定一个内部接脚,接脚必须是一个路径的起点(比如一个触发器的时钟接脚)。如果一个单元...
其实针对于异步电路,是有专门的sdc的命令来完成这项任务的。 set_clock_groups -asynchronous AI代码助手复制代码 从作用上来看,似乎和falsepath的效果是一样的。那么为什么还有这么个命令呢。 AI代码助手复制代码 设想一下,有两个clock, clka和clkb,属于异步关系,应该怎么设置呢?
Hi, I've tried to constrain my project in timequest. One register in design is clocked by 200 Hz, so i decided not to constrain this clock, but use set_false_path SDC command. set_false_path -from [get_pins {Gen|clkA|regout}] -to [get_pins {Diagn|regA|clk}] regA is the ...
Should be no problem to use the sdc constraint, if there a problem, you will see the constraint being ignored in the Report Ignored SDC in the Timing Analyzer. Let me add more info: The set_false_path command tells the timing analyzer not to analyze a path or group of ...
Within Vivado (and SDC/XDC) path enumeration is done the same way for all commands that need to select paths (these being the timing exception commands, set_false_path, set_multicycle_path, set_min_delay, set_max_delay and the path reporting commands, like report_timing, get_timing_paths...
对于异步时钟,当我们书写SDC时,可以使用set_false_path语句来指定由于异步时钟导致的timing exceptions。 set_false_path-from [get_clocks CLKA] -to [get_clocks CLKB]]. 只能指定单方向路径的timing exceptions。如果需要指定双向的timing exceptions,则需要 ...
先上结论 : 1. 同步时钟域: 不需要timing check 的 path 才用 set_false_path ,only disable timing analyze; 2. 异步时钟域: set_clock_group -async 同步时钟域和异步时钟域 的 Timing window: 如图,在cro…