Event driven and cycle based simulation software

This is done by placing the identification of the gate into another queue called the gate queue. Heres the explanation helps you understand this event based simulator. In this paper, a revised cyclebased algorithm is proposed and implemented in vhdl simulator. Many times we get confused to this simple topic difference between event based simulator and cycle based simulator. Fast, easy, flexible dynamic simulation for lifecycle results. The former is most effective for cyclebased twovalued simulation.

An extended example will now illustrate one of the more common uses of a priority queues, which is to support the construction of a simulation model. Cycle based simulator provides a gain of speed with the reduction of resolution. Due to these considerations, almost all commercial logic simulators have an event based capability, even if they primarily rely on cycle based techniques. The most commonly used logic simulation techniques are compiledcode simulation and eventdriven simulation wang 2006. Eventdriven simulation engine and cyclebased simulation engine have been imbedded in the same simulation. Each event occurs at a particular instant in time and marks a change of state in the system.

Discrete eventbased simulation discrete eventbased simulation centralized or. Synopsys new highestperformance vhdl simulator expands support for system design and verification. In the eventdriven execution scheme, a runtocompletion step is executed each time an event is raised. Planning eventdriven simulation 2016 software design. Basic difference between event based simulator and cycle based. For example, all of the combinational logic between a set. In the eventbased approach, the system attributes to consider first are the events, inputs, and outputs. Eventdriven simulation based on tabledriven simulation event. The state machine can define one of two different execution schemes. For example, to create an adapter between cyclebased models and eventdriven models, one will have to map the cycle to a clock, a transaction or an instruction event. It is based on a novel concept of spatial parallelism using accurate prediction of input and output signals of individual local modules in local simulations, derived from a model at a higher abstraction level rtl. For more details, please refer to chapter execution schemes in our documentation. Timedriven simulation is suitable here because there is an event movement that happens at each time step.

Eventdriven simulation another approach is eventdriven 69, which is also known as the discrete event simulation approach. Synopsys new highestperformance vhdl simulator expands. What are the major tradeoffs between cyclebased simulation and. The details of event processing are given in algorithm 32. In other words, the job of the gatelevel simulator is to apply an input vector at the abc primary inputs pis and compute the response values at the g. Save fast, easy, flexible dynamic simulation for lifecycle results learn more about mimic. Event based simulation evaluates inputs looking for state change. The combination of eda and microservices facilitated a simulation system for automation, and a rapid development and testing cycle. Event driven simulation 5 event structures into permanent storage. This makes the simulation very slow compared to cycle based simulators. The integration of cyclebased and eventdriven models in the same simulation environ ment is a challenging task as the semantics for the composition are often not wellde.

Planning eventdriven simulation 2016 previous post in skuvault story. Software system for distributed eventdriven logic simulation. Event based simulation evaluates inputs looking for state change schedule events in time calculate time delay store state values and time information identify timing violations cycle based simulation evaluate entire design every. Runs in browser and a guibased modeling tool is supported. This example demonstrates the two different execution schemes of yakindu statecharts. Low cost cycle based simulation is a good compromise. Software agents an agent is an encapsulated computer system that is. In the following table, consider the characteristics of the eventdriven feeder model that are different from the system based on transition conditions.

Cyclebased algorithm has very high performance for the simulation of synchronous design, but it is confined to synchronous design and it is not as accurate as eventdriven algorithm. The simulation of a certain processing element is performed only as soon as a simulation event occurs a simulation event is a change of the contents in at least one of the input or output registers of a pe cyclebased instruction set simulation is used between events in order to achieve higher simulation speeds as compared to rtl. Cyclebased simulation is a class of eventbased simulation where you only consider clock events. Does your stateflow chart fully express the logical or eventdriven components of your system. Kevin cameron, an ee who spends his time doing software. State key laboratory of simulation and regulation of water cycle in river basin, research center on flood and drought disaster reduction of the ministry of water resources, china institute of. Vcs and nc verilog cycle based or event based simulator. Let me respectfully suggest that one way to at least start to get the lay of the land with respect to circa 50 available discreteevent simulation software packages is to obtain prof. Basic approach for modeling eventdriven systems with stateflow charts. Development of an event based robotic simulation implemented in process simulate samir dalili marcus persson c samir dalili, marcus persson, 2009 report no. Cyclebased and eventdriven simulators can conceptually accept the. Visualize an eventbased simulation model made in process.

Does anyone know what is the best software tool for. Cycle based concept reduce the number of calculation. If nothing is specified, the cyclebased execution scheme with a time interval of 200 milliseconds is used for simulation. A discreteevent simulation des models the operation of a system as a sequence of events in time. Talking about vcs, it is an eventdriven simulator, but it contains many optimization techniques, one of them being cyclebased acceleration. Visualize an eventbased simulation model made in process simulate master of science thesis performed for volvo cars corporation, sweden. Between consecutive events, no change in the system is assumed to occur. A new distributed eventdriven gatelevel hdl simulation. Technologies for design verification kurt keutzer 20 matching problems and technologies event driven interactive phase high flexibility quick turnaround time good debug capabilities cyclebased simulation regression phase highest performance highest capacity emulation and acceleration insystem verification. Rtl synchronous fsm is an eventbased simulation level below that, and asynchronousfsm or tlmdataflow is a level above that that doesnt consider the clocks, but is also eventbased. Can ant body tell me which one is cycle based simulator and which one is event based simulator. Heres a general algorithm for timedriven simulation. The cyclebased simulation paradigm for tlm cyclebased scheduling is an approach in tlm to cope with the simulation speed issues, and this is particularly relevant for cycleaccurate soc models.

Eventdriven online machine state decision for energy. The authors identified that there was a distinct lack of product life cycle tools that are able to model energy use for. Simulator architectures and operations, including eventdriven, cyclebased, hybrid, and hardwarebased simulators. Mathworks is the leading developer of mathematical computing software for engineers and. This is a function that checks for the occurrence of events, and then calls the matching event handler to process it. Ten software packages were assessed in the product lifecycle category and twenty were considered in the energy management category. For example, an event based simulator will order the execution of combination logic blocks so that each block only needs to execute once per clock cycle. Simulation based on events in logic means that whenever there is change in a input event, the output is evaluated.

Enabling heterogeneous cycle based and event driven simulation in a design flow integrated using the spirit consortium specifications. Objects in the simulation model objects in the real world, and are programmed to react as much as possible as the real objects. A new hybrid datadriven model for eventbased rainfall. Js is a generalpurpose discrete event simulation library written entirely in javascript. Code coverage cycle based simulation property checking abv deliverables cyclebased simulation in the verification flow 6 event driven cyclebased sanity check triggers, constructs, combinational loops faster simulation first trials acceleration emulation event driven gate level simulation logic synthesis. A variation to cyclebased approach is to synchronize at every n cycle instead of every cycle 34. Identify system attributes for eventdriven systems. In the hard disc model, all particles travel in straight line trajectories at constant speeds between collisions.

List of discrete event simulation software wikipedia. As soon as you introduce a few different clocks, andor asynchronous signals, the performance advantage of a cyclebased simulator goes down rapidly. Pdf eventdriven simulation of digital circuits using. Event driven scheduling tends to have slow simulation speed compared to what virtual platform creators and users expect. Eventdriven scheduling tends to have slow simulation speed compared to what virtual platform creators and. A discrete eventdriven simulation is a popular simulation technique. For rtl simulations, there is no need to specify a fine resolution since we are only interested in clock cycle by clockcycle behaviour and the transfer functions are. Why hdl i think we are the reason behind the invention of this language. Thus, our main challenge is to determine the ordered sequence of particle collisions. In comparison to event simulation, cycle simulation tends to be faster, to scale. Event simulation also has the advantage of greater flexibility, handling design features difficult to handle with cycle simulation, such as asynchronous logic and incommensurate clocks. Since it can not test physical characteristic of a design, event driven simulator may be used in conjunction. Nevertheless, improved simulation performance comes with a penalty of greater inaccuracy.

Event simulation versus cycle simulation basically, i think of event driven simulators as including timing delays and 10xzrweakstrong signal strengths and cycle simulation as having only 10 logic states and no use of individual delays. Eventdriven gatelevel logic simulation using a timing. Hence, not suitable for initial tests that needs many changes. In my previous article i shared with you through some of growth pains of an eventdriven business system. Efficient eventdriven simulation of parallel processor. With eventdriven simulation we focus only on those times at which interesting events occur. A key challenge is to specify how to synchronize the two different scheduling techniques to allow correct and precise communication between the different models. Cyclebased algorithm used to accelerate vhdl simulation. The technology breakthrough delivers the highestperformance and largest capacity available in any. Eventdriven simulation of digital circuits using modified petri nets algorithm. We can use either the criterion of time reaching a certain point, or the model reaching a certain state, or some combination of the two.

Multiparadigm guibased modelling and simulation software for complex dynamic systems in the earth, environmental and life sciences. The third step in developing an eventdriven program is to write the main loop. Enabling heterogeneous cyclebased and eventdriven simulation. An eventbased simulation model was built in process simulate with operations and all nec. However, many of the concepts from cycle based simulation have been used to optimize event driven simulators. End user never have any control to choose between cycle based and event based simulation in vcs. The second part is to schedule all gates in the fanout of a net for simulation. Most eventdriven programming environments already provide this main loop, so it need not be specifically provided by the application programmer. Logic simulation wikipedia, the free encyclopedia scroll down to. Eventdriven simulation if events arent guaranteed to occur at regular intervals, and we dont have a good bound on the time step it shouldnt be so small as to make the simulation run too long, nor so large as to make the number of events unmanageable, then its more appropriate to use an eventdriven simulation. Eventbased simulators operate by taking events, one at a time, and propagating them through a design until a steady state condition is achieved. Cycle based simulators and emulators may have long compilation. How ousta simulates rides within a twominute test cycle. Logic simulation is the use of simulation software to predict the behavior of digital circuits and.

In this paper we cover an approach for cyclebased and eventdriven mixed simulation. Cycle based vs event based simulators verification academy. Based on dynamic and kinematic behaviors of machine tools, bi et al. Digital hardware implementation of petri net based. Basic difference between event based simulator and cycle. Eventdriven gatelevel logic simulation using a timing wheel data structure ece470 digital design ii imagine how the circuit in fig. A new hybrid datadriven model named pbk has been proposed to improve the eventbased rainfallrunoff simulation. However, many techniques for optimizing cycle based simulation have work their way into eventbased simulators. Ex1002009 department of signals and systems division of automatic control, automation and mechatronics chalmers university of technology se412 96 g oteborg sweden telephone.