Set clock latency. # Specifies the clock latency for a given clock.

Set clock latency. Q4) Write commands to specify Source Latency and Network Latency. 0 CLKA These are the constraint commands used in ASIC designs. 5ns。 set_clock_latency 0. set_cloCK_latency -0. In this part basically, we set clocks definition, clock group, clock latency, clock uncertainty, clock transition, input delay, output delay, timing derates etc. This requirement ensures that all signal paths are constrained for timing. place opt后，CTS之前，design database，关于pin的clock_latency, 在SDC中定义中有如下定义： set_clock_latency7 [get_pins {xxx/A/CK}] set_clock_latency-1 [get_pins {xxx/B/CK}] 两个CK pin均为launch path！ CTS时，tool自动产生的spec文件针对上述latency转变为了以下语句： set_ccopt_property insertion_delay -pin xxx/A/CK-1 set_ccopt_property insertion_delay There are two other ways to handle clock delays/skew, either with an offset when defining the clock, or set_clock_latency. set_clock_latency -source -late 1. 请问set_clock_latency 设太大会有什么不好，除了需要多加buffer和面积变大之外，还有什么不好的影响吗？ 请问set_clock_latency 设太大会有什么不好 ,EETOP 创芯网论坛 (原名：电子顶级开发网) set_propagated_clock [all_clocks] => Specifies that delays be propagated through the clock network to determine latency at register clock pins. Netlist clocks can be referred to using The Set Clock Latency (set_clock_latency) constraint allows you to specify additional delay (that is, latency) in a clock network. I tried something : set_min_delay 0. set_propagated_clock [all_clocks] I have never needed to specify source latency, so my answer is about network latency only. TCL Commands and Packages 4. In this article, CE Timing at placement Step Tightening available cycle time by changing ICG setup time set timing_scgc_override_library_setup_hold true set_clock_gating_style–setup 400ps clock_gate Tightening available cycle time by changing ICG clock latency Standard design constraints or Synopsys design constraints contains the timing and power related constraints which control design wrt to the spec. we set some max fan out limit by using set_max_fanout. 5 This article mainly focuses on minimization clock latency during physical implementation with Synopsys IC Compiler. periph::check_plan (::quartus::periph) 3. periph::get_cell_info (::quartus::periph) 3. 1 -fall [all_clocks] 这两条命令表示的是 时钟网络延迟，也就是上图的 ② 部分。 上升延迟 0. Note: This command operates silently and does not return direct feedback of its operation. How to specify clock latency: In EDA tools, we can model clock latency using SDC command ‘set_clock_latency’ to imitate the behavior there will be after clock tree will be built. These are the constraint commands used in ASIC designs. If not specified, ideal clocking is assumed. clock latency：clock源到时序器件的clk脚的延迟叫做clock latency. Can I do that ? The following sdc didn't work. 1个单位，并且将其标记为最小延迟；而引用中的命令将时钟延迟设置为0. periph::get_cells (::quartus::periph) 3. 1: Valid for Synopsys The set_clock_latency command allows designers to model the behavior of the clock after the clock tree synthesis (CTS) has been completed. They behave differently, and usually I would choose set_clock_latency (I don't think 对于clock 一直感觉没有理解到实质，这篇文章是网上搜索到的，加以理解发了出来 1. 3. 1: Valid for Synopsys tools, the behaviour can be different for other EDA vendors. 2 [get_clocks clk] 3|3时钟延迟 (latency)的建模 命令为set_clock_latency。 如上述概念所述，latency包含source latency和network latency，二者需要分开进行约束。 在DC过程中通常仅对source Description This command defines a clock's source or network latency for specified clocks, ports, or pins. Libero SoC Design Suite Help Documentation - Revision 2025. 1ns，最大延迟0. Post-CTS clock gating timing path. Q4) Explain Pre CTS and Post CTS Latency. The diagram below Hello everyone, I have a design where on the top level I have a clock signal as a port and I want to make sure it arrives with a delay at a specific pin inside the hierarchy. Fig. Hi, can anyone pls explain how should i use this command? should i set the latency on the clock port? does it affect the early or late path? if i have gated clocks in my design, i must use also set_clock_gate_latency? Thanks! The following table displays information for the set_clock_latency Tcl command: Tcl Package and Version Belongs to ::quartus::sdc 1. This delay value represents the external delay from a virtual (or ideal) clock through the longest Late (-late) or shortest Early (-early) path, with reference to the Rise (-rise) or Fall (-fall) of the clock transition. Quartus® Prime Pro Edition User Guide Scripting Archives A. Description This command defines a clock's source or network latency for specified clocks, ports, or pins. Q4) Explain Description This command defines a clock's source or network latency for specified clocks, ports, or pins. If the constraint is incorrect, then you're compiling with incorrect timing analysis and some of the time it may just This brings more flexibility. This is useful in two cases: To specify the clock delay propagation outside the device independently from the input and output delay constraints. The following table displays information for the set_clock_latency Tcl command: Tcl Package and Version Belongs to ::quartus::project 5. Understanding clock latency is essential to ensure your circuits meet timing requirements and operate efficiently. 1. Command Line Scripting 2. 0 Syntax set_clock_latency [-h | -help] [-long_help] [-early] place opt后，CTS之前，design database，关于pin的clock_latency, 在SDC中定义中有如下定义： set_clock_latency 7 [get_pins {xxx/A/CK}] set_clock_latency -1 关于set_clock_latency的疑问 ,EETOP 创芯网论坛 (原名：电子顶级开发网) DC综合的 约束文件 中需要创建时钟，设置时钟的各种参数。包括：clock period、clock latency、clock transition、clock uncertainty等。 下面记录一下时钟的一些参数： （1）、clock skew 时钟分支信号在到达寄存器的时钟 HFN's are the nets which drives more number of load as compared to other nets. As you noted, Clock Latency CLK NOTE: Altera’s TimeQuest analyzer automaAcally computes network latencies; therefore, you only can characterize source latency with the set_clock_latency command. create_clock –name SYSCLK –period 10. 000 [get_clocks SYSCLK] -> -source 옵션을 사용하지 않으면 기본적으로 Network latency 값을 지정해주는 것이 된다. 5 Syntax set_clock_latency [-h | -help] [-long_help] [-clock set_clock_latency 1 [get_clocks CLK]这个命令。 基本的时钟建模就OK了，下面进行总结并给出我们这个例子中使用的约束脚本，理想时钟和实际时钟的对比，如下图所示： Clock latency plays a crucial role in the accurate functioning of digital circuits. VerificationmasterSo, from this blog you can answer the below set of questions: Q1) What is Clock Latency? Q2) What are the categories of Clock Latency? Q3) Define Source Latency and Network Latency. The following table displays information for the set_clock_latency Tcl command: Set Clock Latency (set_clock_latency)约束使您能够制定时钟网络中的额外延迟 (也就是，latency)。此延迟值代表从虚拟 (或理想)时钟到最长Late (-late)或者最短Early (-early)路径的外部延迟，参考时钟跳变的Rise (-rise)或者Fall (-fall)。 Fig. clock tree：从一个clock源出发，clock网络经过多级buffer，到达每个时序器件的clk脚。 Dear all, I need some guidance on how to perform a proper timing analysis in Innovus to ensure all paths meet the performance requirements. Slack margin overrides-based clock annotations. AMD 以外のタイミング エンジンを使用している場合は通常、クロック ツリーの伝搬遅延が算出されるようにするため、set_propagated_clock という SDC コマンドを使用する必要があります。 Vivado ツールではこのコマンドは必要ありません。 set_clock_latency是一个在clk上与input_delay相对于是概念。 他们的意思都是信号从port进来，跑到reg上所要用的时间，只不过input_delay是data信号，并且只会接触有限的reg，而clk_latency是针对clk信号，所有这个时钟 set_clock_latency -source 3. Unlock your system's true potential. In ASIC designs, you do synthesis of the design before the clock tree has been inserted, and the set_clock_latency -network is used as an "early placeholder" for the expected clock insertion delay. set_clock_latency depends on the board and traces which establish the delay between the oscillator output pin, and the programmable logic input pin. sdc commands that accommodate various clocking schemes, such as: The set_clock_latency constraints are used to specify the clock latency through the STARTUPE2 primitive and board trace when it arrives at the SPI Flash. To model the internal propagation latency of a cl # Specifies the clock latency for a given clock. Source latency is the time in nanoseconds that a clock signal takes to The Set Clock Latency (set_clock_latency) constraint allows you to specify additional delay (that is, latency) in a clock network. The obstacles in optimizing clock networks may come from many aspects. 22. This delay value represents the external delay from a virtual (or ideal) clock through the longest Late (-late) or shortest Early (-early) path, with reference to the Rise (-rise) or Fall (-fall) of the clock Source latency is the latency from the ideal waveform to the source pin or port and -source option in the set_clock_latency command represents just that only. How to do Note that once the set_propagated_clocks is used for analysis (post-CTS), the analyzer calculates the Actual clock skew, Latency (both Network and Source) in case of generated clock and (Network) in case of Master clock, and clock transition time. In this article, we will explore the concept of clock latency, its components, and how it affects timing analysis. Verify all content and data in the device’s PDF documentation found on the device product page. Source Synchronous Input Timing ¶ A source synchronous input is an interface in which the data is co-incident with a clock. Clock network latency is useful in controlling the behavior of optimization during pre-clock-tree stages, in constraint command: set_clock_latency. v file) and 本文详细介绍了FPGA设计中的时序约束，特别是set_clock_latency约束的概念和作用。时序约束对规范设计时序行为至关重要，而set_clock_latency用于指定时钟源延迟和时钟网络延迟，确保综合和布局布线满足预期的时序要求。同步与异步时钟的区分以及不可扩展时钟的定义进一步丰富了时钟约束的背景知识。 The following table displays information for the set_clock_latency Tcl command: Tcl Package and Version Belongs to ::quartus::project 5. 在sta时，都会将latency加到data arrival、data require上，计算slack时会抵消 Clock latency只能模拟时钟树综合前的理想时钟的网络延迟，一旦时钟树综合完成，理想时钟会被转化为传播时钟，此时传播时钟的有关网络延迟相关 二、时钟例外 Vivado 的时序约束中，考虑时钟不稳定影响的约束包括set_clock_latency, set_clock_uncertainty,set_input_jitter， set_system_jitter，这些约束可分为两类：clock latency和clock 本文基于innovus工具讨论。基于block level的设计进行时序分析，如果在SDC和flow脚本中对clock 没有设置source clock latency 和network clock latency，在ccopt之前clock模式是ideal的，所有的clock latency都是 Aquí nos gustaría mostrarte una descripción, pero el sitio web que estás mirando no lo permite. Answers to Top FAQs 1. create_clock Creates a netlist or virtual clock. This is also called network delay from the clock output from source generating it to the point under consideration. 0 [get_ports CLK] set_clock_latency –source 3. Using this command, we can specify both the Clock latency of CDC clocks is factored into the max delay timing, unless using -ignore_clock_latency with set_max/min_delay: pt_shell> set_clock_latency 2. You should also define the uncertainty, latency, and transition constraints for each clock by using the set_clock_uncertainty, set_clock_latency, and The Set Clock Latency (set_clock_latency) constraint allows you to specify additional delay (that is, latency) in a clock network. Unless multiple related clocks are coming into the FPGA, it only affects I/O timing, but it certainly will give a different result. By specifying both the source latency and the network latency The Set Clock Latency (set_clock_latency) constraint allows you to specify additional delay (that is, latency) in a clock network. 0 [get_clocks C1] Clock source latency impacts the way setup and hold check may be performed when multiple clocks are interacting. Quartus® Prime Pro Edition User Guides Clock latency of CDC clocks is factored into the max delay timing, unless using -ignore_clock_latency with set_max/min_delay: pt_shell> set_clock_latency 2. As you noted, in an FPGA, the clock tree is always inserted. The nets which have greater than these limits are set_clock_transition -max 0. Then, and only for clock- gating Description This command defines a clock's source or network latency for specified clocks, ports, or pins. 上述命令直接由时序分析工具，在CTS之后自动计算clock latency。 理想网络延迟（Ideal Network Latency）：在CTS及PR阶段之前，评估并直接指定该延迟。 可以通过set_clock_latency命令指定该延迟，该命令的语法如下： I want to set different clock uncertainity values in the same sdc file for both pre and post CTS modes. 5个单位，并且将其标记为最大 set_clock_latency 0. 5 -source -early [get_clocks CLK] For Setup analysis, it uses the late value for each startpoint and the early value for each endpoint. 9ns ，下降延迟1. set_external_check set_clock_to_output Clock-to-clock Uncertainty set_clock_uncertainty Clock Source Latency set_clock_latency Refer to "Timing Constraints and Design Flow" on page 7 for the Timing Assertion SDC commands Synplify Pro and SmartTime support. The online versions of the documents are provided as a courtesy. Source latency is the time in nanoseconds that a clock signal takes to propagate from its waveform origin to the clock definition point Clock Latency: Clock latency is the time delay seen between the clock edges of the clock signal at its source of generation and the same signal at the destination, where it is connected to the input of a sequential element. This time, as highlighted above, its ‘set_clock_transition’ and ‘slew’. 4. 0 CLKA How to specify clock latency: In EDA tools, we can model clock latency using SDC command ‘set_clock_latency’ to imitate the behavior there will be after clock tree will be built. 1ns。 最后，以上内容均为个人见解，如果错误，还请指正。 ×Sorry to interruptCSS Error 或者在DC 中开启ccd ， 通过write_scripts 写出工具根据组合逻辑和你的设置推出来的tree长度脚本set_clock_latency -offset ， 通过脚本转换set_clock_latency -offset 为标准set_clock_latency -clock xxx [get_pins SDC Commands The following subset of SDC syntax is supported by VPR. The clock latency estimator provides the expected delay of every clock net in the design. pt_shell> set_clock_latency 2. DC中，约束的时候，需要添加关于latency的约束。约束latency的命令是set_clock_latency。使用man命令，查看。这里，有个技巧，可以将man的结果重定向到一个临时文件中，可以可以方便查看。 sh表示使用shell命令。 If clock latency of the pin is represented by a pin-specific network latency using the set_clock_latency SDC command, this information is translated to the automatically-generated clock tree specification. 2. 什么是虚拟时钟？ 虚拟时钟（virtual clock）是存在但没有clock source (pin/port)定义的时钟，仅作为输入输出端口延时约束的 The following table displays information for the set_clock_latency Tcl command: Tcl Package and Version Belongs to ::quartus::sdc 1. This delay value represents the external delay from a virtual (or How to specify clock latency: In EDA tools, we can model clock latency using SDC command ‘set_clock_latency’ to imitate the behavior there will be after clock tree will be built. Tcl Scripting 3. The Timing Analyzer supports . For AMD FPGAs, use the set_clock_latency command primarily to specify the clock latency outside the device. 5k次，点赞13次，收藏50次。本文详细介绍了同步电路设计中的时钟约束，包括时钟源点、时钟周期、时钟占空比、时钟命名、时钟转换延时、时钟不确定性以及时钟延迟等关键概念，通过具体 You must define all clocks and any associated clock characteristics, such as uncertainty, latency or skew. 5ns (注意这里的network delay其实指的是总延迟，而不只是网络延迟)，括号中的ideal提示了这是一个理想时钟。 Vivado的时序约束中，考虑时钟不稳定影响的约束包括set_clock_latency, set_clock_uncertainty,set_input_jitter，set_system_jitter，这些约束可分为两类：clock latency和clock uncertainty 另外，假定时钟树中存在的任何单元也具有零延迟。 在逻辑综合阶段， STA 通常以理想的时钟路径执行，分析的重点放在数据路径上。 在理想的时钟树中，默认clock skew为0ps。 时钟树的clock latency可以显式地使 VerificationmasterSo, from this blog you can answer the below set of questions: Q1) What is Clock Latency? Q2) What are the categories of Clock Latency? Q3) Define Source Latency and Network Latency. 300 [get_pins ICG/CK] 在CTS阶段，在Reg1的CK pin上设置一个insert delay，这就是所谓的floating pin，这个insert delay的值大概也等于CTS后T3（ICG→reg2的时钟树长度）的大小。 Please select the desired version. Source latency is the time in nanoseconds that a clock signal takes to propagate from its waveform origin to the clock definition point You access this dialog box by clicking Constraints > Set Clock Latency in the Timing Analyzer, or with the set_clock_latency Synopsys Design Constraints (SDC) command. 2. 0 Syntax set_clock_latency [-h | -help] [-long_help] [-early] Generated clocks are treated by the STA tool as synchronous to master/base clocks and automatically infers source latency = source latency of base clock + latency between the base and generated clock definition points. 文章浏览阅读5. It can be used to model the clock insertion delay or skew that will occur after building the tree ahead of time. The board hardware engineer would have info on the delay. At a minimum, the timing constraints must constain a clock definition for each clock signal, as well as input delay or output delay for each I/O port. periph::get_location_info This brings more flexibility. The insertion delay includes the propagation delay from USERCCLKO to CCLK pin and the trace delay on the board. set_clock_latency 是一个在综合和时序分析中使用的指令，用于指定时钟网络中的额外延迟，也就是latency。这个延迟值代表从虚拟（或理想）时钟到最长Late（-late）或者最短Early（-early）路径的外部延迟，参考时钟跳变 Aquí nos gustaría mostrarte una descripción, pero el sitio web que estás mirando no lo permite. First, in my Innovus scripts, I feed the design (. 5 Syntax set_clock_latency [-h | -help] [-long_help] [-clock Description This command defines a clock's source or network latency for specified clocks, ports, or pins. Source latency is the time in nanoseconds that a clock signal takes to propagate from its waveform origin to the clock definition point You have to understand that XDC is derived from SDC - the Synopsys Design Constraints. set_clock_latency是一个时钟延迟设置的命令。 通过这个命令可以设置时钟信号在时序单元输入端的延迟。 具体来说，引用中的命令将时钟延迟设置为0. 9 -rise [all_clocks] set_clock_latency 1. In addition, there is a known relationship between the clock and the data. 3. Source latency is the time in nanoseconds that a clock signal takes to propagate from its waveform origin to the clock definition point The only difference between set_clock_latency snippet and above set_clock_transition snippet is the search keyword and append keyword. 5 [get_clock clk] 图2所示的建立时间时序报告显示，时钟的总延迟为2. 000 [get_clocks SYSCLK] The following table displays information for the set_clock_latency Tcl command: It is possible to model the latency of a clock at its source by using the set_clock_latency command with the -source option. Regarding second qn. Using this command, we can specify both the What's the value of set_clock_latency? This command adds delay to the clock and can be used to model external clock delays. 1, Version 16 Discover how clock latency impacts Static Timing Analysis (STA) and the significance in digital circuit design. There are two types of latency: network and source. Assigns a desired period (in nanoseconds) and waveform to one or more clocks in the netlist (if the –name option is omitted) or to a single virtual clock (used to constrain input and outputs to a clock external to the design). Source latency is the clock network delay between the clock definition pin and its source, while network latency is the clock 部分。 最小延迟0. qpic gifxt fajdec hjtxwrk kbgyz gdygry pbuit ehfj ojvi cuvj