Verification Academy

Search form

My Account Menu

  • Register
  • Log In
  • Topics
  • Courses
  • Forums
  • Patterns Library
  • Cookbooks
  • Events
  • More
  • All Topics
    The Verification Academy offers users multiple entry points to find the information they need. One of these entry points is through Topic collections. These topics are industry standards that all design and verification engineers should recognize. While we continue to add new topics, users are encourage to further refine collection information to meet their specific interests.
    • Languages & Standards

      • Portable Test and Stimulus
      • Functional Safety
      • Design & Verification Languages
    • Methodologies

      • UVM - Universal Verification Methodology
      • UVM Framework
      • UVM Connect
      • FPGA Verification
      • Coverage
    • Techniques & Tools

      • Verification IQ
      • Verification IP
      • Static-Based Techniques
      • Simulation-Based Techniques
      • Planning, Measurement, and Analysis
      • Formal-Based Techniques
      • Debug
      • Acceleration
  • All Courses
    The Verification Academy is organized into a collection of free online courses, focusing on various key aspects of advanced functional verification. Each course consists of multiple sessions—allowing the participant to pick and choose specific topics of interest, as well as revisit any specific topics for future reference. After completing a specific course, the participant should be armed with enough knowledge to then understand the necessary steps required for maturing their own organization’s skills and infrastructure on the specific topic of interest. The Verification Academy will provide you with a unique opportunity to develop an understanding of how to mature your organization’s processes so that you can then reap the benefits that advanced functional verification offers.
    • Universal Verification Methodology (UVM)

      • Introduction to UVM
      • UVM Basics
      • Advanced UVM
      • UVM Connect
      • UVM Debug
      • UVMF - One Bite at a Time
    • Featured Courses

      • Introduction to ISO 26262
      • Introduction to DO-254
      • Clock-Domain Crossing Verification
      • Portable Stimulus Basics
      • Power Aware CDC Verification
      • Power Aware Verification
      • SystemVerilog OOP for UVM Verification
    • Additional Courses

      • Assertion-Based Verification
      • An Introduction to Unit Testing with SVUnit
      • Evolving FPGA Verification Capabilities
      • Metrics in SoC Verification
      • SystemVerilog Testbench Acceleration
      • Testbench Co-Emulation: SystemC & TLM-2.0
      • Verification Planning and Management
      • VHDL-2008 Why It Matters
    • Formal-Based Techniques

      • Formal Assertion-Based Verification
      • Formal-Based Technology: Automatic Formal Solutions
      • Formal Coverage
      • Getting Started with Formal-Based Technology
      • Handling Inconclusive Assertions in Formal Verification
      • Sequential Logic Equivalence Checking
    • Analog/Mixed Signal

      • AMS Design Configuration Schemes
      • Improve AMS Verification Performance
      • Improve AMS Verification Quality
  • All Forum Topics
    The Verification Community is eager to answer your UVM, SystemVerilog and Coverage related questions. We encourage you to take an active role in the Forums by answering and commenting to any questions that you are able to.
    • UVM Forum

      • Active Questions
      • Solutions
      • Replies
      • No Replies
      • Search
      • UVM Forum
    • SystemVerilog Forum

      • Active Questions
      • Solutions
      • Replies
      • No Replies
      • Search
      • SystemVerilog Forum
    • Coverage Forum

      • Active Questions
      • Solutions
      • Replies
      • No Replies
      • Search
      • Coverage Forum
    • Additional Forums

      • Announcements
      • Downloads
      • OVM Forum
  • Patterns Library
    The Verification Academy Patterns Library contains a collection of solutions to many of today's verification problems. The patterns contained in the library span across the entire domain of verification (i.e., from specification to methodology to implementation—and across multiple verification engines such as formal, simulation, and emulation).
    • Implementation Patterns

      • Environment Patterns
      • Stimulus Patterns
      • Analysis Patterns
      • All Implementation Patterns
    • Specification Patterns

      • Occurrence Property Patterns
      • Order Property Patterns
      • All Specification Patterns
    • Pattern Resources

      • Start Here - Patterns Library Overview
      • Whitepaper - Taking Reuse to the Next Level
      • Verification Horizons - The Verification Academy Patterns Library
      • Contribute a Pattern to the Library
  • All Cookbooks
    Find all the methodology you need in this comprehensive and vast collection. The UVM and Coverage Cookbooks contain dozens of informative, executable articles covering all aspects of UVM and Coverage.
    • UVM Cookbook

      • UVM Basics
      • Testbench Architecture
      • DUT-Testbench Connections
      • Configuring a Test Environment
      • Analysis Components & Techniques
      • End Of Test Mechanisms
      • Sequences
      • The UVM Messaging System
      • Other Stimulus Techniques
      • Register Abstraction Layer
      • Testbench Acceleration through Co-Emulation
      • Debug of SV and UVM
      • UVM Connect - SV-SystemC interoperability
      • UVM Versions and Compatibility
      • UVM Cookbook
    • Coding Guidelines & Deployment

      • Code Examples
      • UVM Verification Component
      • Package/Organization
      • Questa/Compiling UVM
      • SystemVerilog Guidelines
      • SystemVerilog Performance Guidelines
      • UVM Guidelines
      • UVM Performance Guidelines
    • Coverage Cookbook

      • Introduction
      • What is Coverage?
      • Kinds of Coverage
      • Specification to Testplan
      • Testplan to Functional Coverage
      • Bus Protocol Coverage
      • Block Level Coverage
      • Datapath Coverage
      • SoC Coverage Example
      • Requirements Writing Guidelines
      • Coverage Cookbook
  • All Events
    No one argues that the challenges of verification are growing exponentially. What is needed to meet these challenges are tools, methodologies and processes that can help you transform your verification environment. These recorded seminars from Verification Academy trainers and users provide examples for adoption of new technologies and how to evolve your verification process.
    • Featured & On-Demand

      • Exploring Formal Coverage
      • Processor Customization
      • Interconnect Formal
      • Formal and the Next Normal
      • Formal Verification Made Easy
      • Data Independence and Non-Determinism
      • Exhaustive Scoreboarding
      • Visualizer Debug Environment
      • Webinar Calendar
    • On-Demand Library

      • SystemVerilog Assertions
      • Practical Flows for Continuous Integration
      • Continuous Integration
      • Questa Verification IQ
      • Avery & Siemens VIP
      • Protocol and Memory Interface Verification
      • HPC Protocols & Memories
      • Preparing for PCIe 6.0: Parts I & II
      • High Defect Coverage
      • SoC Design & Functional Safety Flow
      • Complex Safety Architectures
      • All On-Demand Recordings
    • Recording Archive

      • Lint vs Formal AutoCheck
      • FPGA Design Challenges
      • Design Solutions as a Sleep Aid
      • Fix FPGA Failures Faster
      • CDC and RDC Assist
      • The Dog ate my RTL
      • Questa Lint & CDC
      • Hierarchical CDC+RDC
      • Improving Initial RTL Quality
      • CDC Philosophy
      • Hardware Emulation Productivity
      • The Three Pillars of Intent-Focused Insight
      • All Webinar Topics
    • Conferences & WRG

      • 2022 Functional Verification Study
      • Improving Your SystemVerilog & UVM Skills
      • Automotive Functional Safety Forum
      • Aerospace & Defense Tech Day
      • Siemens EDA Functional Verification
      • Industry Data & Surveys
      • DVCon 2023
      • DVCon 2022
      • DVCon 2021
      • Osmosis 2022
      • All Conferences
    • Siemens EDA Learning Center

      • EDA Xcelerator Academy(Learning Services) Verification Training, Badging and Certification
      • View all Xcelerator Academy classes
  • About Verification Academy
    The Verification Academy will provide you with a unique opportunity to develop an understanding of how to mature your organization's processes so that you can then reap the benefits that advanced functional verification offers.
    • Blog & News

      • Verification IQ
      • Verification Horizons Blog
      • Technical Resources
    • Verification Horizons Publication

      • Verification Horizons - July 2023
      • Verification Horizons - March 2023
      • Verification Horizons - December 2022
      • Issue Archive
    • About Us

      • Verification Academy Overview
      • Subject Matter Experts
      • Academy News
      • Contact Us
    • Training

      • Learning @OneGlance (PDF)
      • SystemVerilog & UVM Classes
      • Siemens EDA Classes
Ask a Question
SystemVerilog
  • Home
  • Forums
  • SystemVerilog
  • Assertion for clock gating

Assertion for clock gating

SystemVerilog 6741
#SVA 96 #systemverilog #ASSERTION 112 Assertion system verilog 70 assertion clock sync 3 assertion clock gating 1
nimitz_class
nimitz_class
Full Access
52 posts
March 27, 2021 at 11:40 am

Hi,

Below are my requirements for clock gating assertion :

1. refclk toggles when both req and ack are asserted. I want to check for the refclk to be
gated or 0 during the other 3 situations,

ie ref = 0 and ack = 0;
ref = 0 and ack = 1;
ref = 1 and ack = 0;

2. I have another clock in my test bench to time this assertion, ie sclk. But my assertion
gets triggered @ every posedge of sclk and hence it fails until req and ack becomes zero.

property refclkDeassert;
          @(posedge sclk) 1 |-> !refclk throughout (!refClkReq && !refClkAck) [*1:$]; 
endproperty

Can someone please suggest a better way to write an assertion for this?

Thanks

Replies

Log In to Reply
ben@SystemVerilog.us
ben@SystemVerilog.us
Full Access
2880 posts
March 27, 2021 at 1:25 pm

In reply to foxtrot:
Your requirements are ambiguous.
Can you create a table or a better description of the requirements?
For example,

  • If ref = 0 and ack = 0 then .. // or is it "if($fell(ref) and ack", or is it "if($fell(ack) ..
  • ....If(..) then ..
  • ...
You need to clarify the antecedents. It is OK (or even better) to have multiple small assertions.
With !refclk throughout (!refClkReq && !refClkAck) [*1:$];
are you trying to say
@(posedge sclk) $fell(req) |-> !refclk throughout (!Req ##[*1:$] !Ack);

The throughout operator specifies that a signal (expression) must hold throughout a sequence.
( b throughout R ) is equivalent to ( b [*0:$] intersect R )
For example, in the following handshake example, a req is honored with an acknowledge within the next 4 cycles. The ack is then followed at a later time by a done control signal. However, there is one additional requirement that throughout the time between the ack and done an enable signal must be asserted to drive a tri-state bus. That assertion can be expressed as follows. Figure 2.4.6 demonstrates a timing diagram that satisfies an assertion of this property.
ap_handshake : assert property (
$rose(req) |-> ##[1:4] enable throughout (ack ##[1:$] done));

Ben Cohen
http://www.systemverilog.us/
For training, consulting, services: contact http://cvcblr.com/home.html
** SVA Handbook 4th Edition, 2016 ISBN 978-1518681448
...
1) SVA Package: Dynamic and range delays and repeats https://rb.gy/a89jlh
2) Free books: Component Design by Example https://rb.gy/9tcbhl
Real Chip Design and Verification Using Verilog and VHDL($3) https://rb.gy/cwy7nb
3) Papers:
- Understanding the SVA Engine,
https://verificationacademy.com/verification-horizons/july-2020-volume-16-issue-2
- SVA Alternative for Complex Assertions
https://verificationacademy.com/news/verification-horizons-march-2018-issue
- SVA in a UVM Class-based Environment
https://verificationacademy.com/verification-horizons/february-2013-volume-9-issue-1/SVA-in-a-UVM-Class-based-Environment
nimitz_class
nimitz_class
Full Access
52 posts
March 27, 2021 at 1:32 pm

In reply to ben@SystemVerilog.us:

Let me simplify and ignore other scenarios. I want the assertion to check for refclk to be gated when req and ack both are zero. Not at any edge, I want it to be level-triggered.

Btw, the assertion I posted earlier will not be useful in my case as it will get triggered at every posedge of sclk and I will see failures throughout my simulation. So, please suggest a better method.

Thanks

ben@SystemVerilog.us
ben@SystemVerilog.us
Full Access
2880 posts
March 27, 2021 at 5:58 pm

In reply to foxtrot:
Below is my approach. Note my use of a delayed sysclk to be used in the concurrent assertion.

/* @(posedge sclk) $fell(req) |-> !refclk throughout (!Req ##[*1:$] !Ack);
I want the assertion to check for refclk to be gated when req and ack both are zero.
 Not at any edge, I want it to be level-triggered.
 req ack gate ref_clk
 0    0   0     0
 0    1   1     ==clk 
 1    0   1     == clk
 1    1   1     == clk
 */
module top;   
  `include "uvm_macros.svh"
  import uvm_pkg::*;
  logic req, ack, ref_clk, gate, sysclk=0, sysclk1; 
  // gate is the enable for the ref_clk to equal the sysclk 
  // sysclk is the system clock 
  // sysclk1 is a delayed sysclk by 1ns; it is used for the conccurrent assertion 
  // I delayed by 1ns to evaluate the signals after they settled from the gating. 
 
  initial forever #10 sysclk = !sysclk;
  assign #1 sysclk1= sysclk;  
  always_comb begin  // Operation of the ref_clk per the design 
      if(req==0 && ack==0) ref_clk=0; 
      else ref_clk = sysclk; 
  end
 
  always_comb begin
    if(req==0 && ack==0) gate=0; // logic for the gate, used in the verification 
    else gate = 1'b1; 
end
 
  always_comb begin  // check on the gate 
      p_ref: assert final (gate==(req || ack));
  end
  // concurrent assertions on the ref clk 
  ap_ref_clk1: assert property(@ (sysclk1) gate |-> ref_clk==sysclk);  
  ap_ref_clk1b: assert property(@ (sysclk1) (req || ack) |-> ref_clk==sysclk);  
  ap_ref_clk0: assert property(@ (sysclk1) !gate |-> ref_clk==0);  
 
  initial begin
    repeat (200) begin
      @(posedge sysclk);
      if (!randomize(req, ack) with {
        req dist {1'b1 := 1, 1'b0 := 1};
        ack dist {1'b1 := 1, 1'b0 := 2};
      })
        `uvm_error("MYERR", "This is a randomize error");
    end
    $finish;
  end
endmodule

Ben Cohen
http://www.systemverilog.us/
For training, consulting, services: contact http://cvcblr.com/home.html
** SVA Handbook 4th Edition, 2016 ISBN 978-1518681448
...
1) SVA Package: Dynamic and range delays and repeats https://rb.gy/a89jlh
2) Free books: Component Design by Example https://rb.gy/9tcbhl
Real Chip Design and Verification Using Verilog and VHDL($3) https://rb.gy/cwy7nb
3) Papers:
- Understanding the SVA Engine,
https://verificationacademy.com/verification-horizons/july-2020-volume-16-issue-2
- SVA Alternative for Complex Assertions
https://verificationacademy.com/news/verification-horizons-march-2018-issue
- SVA in a UVM Class-based Environment
https://verificationacademy.com/verification-horizons/february-2013-volume-9-issue-1/SVA-in-a-UVM-Class-based-Environment

Siemens Digital Industries Software

Siemens Digital Industries Software

#TodayMeetsTomorrow

Portfolio

  • Cloud
  • Mendix
  • Electronic Design Automation
  • MindSphere
  • Design, Manufacturing and PLM Software
  • View all Portfolio

Explore

  • Community
  • Blog
  • Online Store

Siemens

  • About Us
  • Careers
  • Events
  • News and Press
  • Customer Stories
  • Partners
  • Trust Center

Contact

  • VA - Contact Us
  • PLM - Contact Us
  • EDA - Contact Us
  • Worldwide Offices
  • Support Center
  • Give us Feedback
© Siemens 2023
Terms of Use Privacy Statement Cookie Statement DMCA