Gatelevel timing simulation using nativelink feature. Drag from the hollow circles to the solid circles to make connections. To see how the gate level simulation is done we will write the verilog code that that we used for comparator circuit using primitive gates. Using modelsim to simulate logic circuits in verilog designs for quartus prime 16. Running modelsimaltera from the quartus ii software modelsimaltera software simulation user guide january 20 altera corporation 1. Write, compile, and simulate a verilog model using modelsim. This tutorial explains first why simulation is important, then shows how you can acquire modelsim student edition for. The typical rtltogatelevelnetlist flow is shown in the following illustration. Find modelsim training at mentor graphics training centers around the world or at your site. Modelsim tutorial introduction modelsim is a simulation and debugging tool for vhdl, verilog, systemc, and mixedlanguage designs. Verilog has built in primitives like gates, transmission gates, and switches to model gate level simulation. Gate level simulation with modelsim sepe simulator vhdl you can use this design example to learn how to perform gate level timing simulations for designs implemented in stratix ii devices with the mentor graphics modelsim sepe simulator. It means a test which takes x ns in rtl simulation will take the same amount in gate level simulations too.
However, those simulations can take days or weeks to run. In the tool name list, specify simulation tool as modelsim. The design netlist output file is a netlist of the design mapped to architecturespecific primitives. Edition design in the modelsimintel fpga edition simulator. Even today, gate level simulation is still a major signoff step for most semiconductor projects. Ive tried to do some research but the topics ive seen here are more in uvm and system verilog but none for gate level simulations. This vhdl design example describes how to set up and perform a gatelevel timing simulation of a vhdl design implemented in a stratix ii device with modelsim. Later, we are going to use modelsim to simulate our project. Aug 03, 2016 i have been working in gls fullypartly since 2 years in one of the soc company.
We show how to perform functional and timing simulations of logic circuits implemented by using quartus ii cad software. And that modelsimaltera verilog is your simulator you probably did this any way before 3. Ee 108 digital systems i modelsim tutorial winter 20022003 page 4 sur 14 at this point, you would generally run the simulation and analyze or debug your design. As a consequence, simulation does not accurately predict silicon functionality. Read from c through foreign language interface fli, modelsim. Modelsim is a program created by mentor graphics used for simulating your vhdl and verilog designs.
In modelsim, all designs are compiled into a library. Gatelevel simulation methodology improving gatelevel simulation performance author. For now, lets wrap up by ending the simulation and closing the project. It can be used to simulate gate level and transistor level circuits.
Simulation with timing information is also done postfitting known as the timing simulation or gate level simulation. Creating and simulating memories in maxplus2 and modelsim. An rtl or gate level simulation of a design that has more than one clock domain i. As of my knowledge every soc company is depending on gls, even after efficiently using rtl simulations, advancements in static verification tools like sta static tim. Investigate the behaviour of and, or, not, nand, nor and xor gates. This is ok in rtl simulation, but with gls it causes everything to go x. As we can see in the above result when switches s0 0 and s11 the output should be i3 which it is. I have the net list in vhdl format and i need now to simulate it again to be sure the functionality is right after the synthesis. There are many sources of trouble in gate level simulation. Once a problem is found, you can edit, recompile, and resimulate without leaving the simulator. Modelsim supports all microsemi fpga libraries, ensuring accurate timing simulations.
Gate level simulation with modelsimaltera simulatorverilog hdl. Gatelevel timing simulation is an important step in ensuring that the device functionality is correct and meets all timing requirements following. Eda gate level simulation to automatically run the eda simulator, compile all necessary design files, and complete a simulation. In the processing menu, point to start and click on start eda netlist writer. In all cases, getting a gate level simulation up and running is generally accompanied by a series of challenges so frustrating that they invoke a shower of adjectives. In the category list, select simulation under eda tool settings. Gate level timing simulation placeandroute in the quartus ii software produces a design netlist. After you compile your code, select tools and choose gate level simulation. You should now notice that the module included in the library is pointing to a. You typically start a new simulation in modelsim by creating a working library called work. Verilog tutorial electrical and computer engineering. This tutorial explains how to write and simulate verilog code for nand gate on modelsim. You typically start a new simulation in modelsim by creating a working library called work, which is the default library name used by the compiler as the default destination for compiled design units. Using modelsim to simulate logic circuits in verilog designs.
For this tutorial we will be performing gate level simulation on the netlist of the synthesized, placed, and routed greatest common divisor gcd circuit, which you should have generated in tutorial 3. Logic simulation is the use of simulation software to predict the behavior of digital circuits and hardware description languages. Functional simulation and gate level simulation using synopsys vcs compiler. These three examples will help you clear out the idea of gate level modelling using verilog. Modelsim tutorial basic simulation flow the following diagram shows the basic steps for simulating a design in modelsim.
Start a new quartus project using the project wizard and choose sums as the name of design and top module. I have the net list in vhdl format and i need now to simulate it again to be sure the functionality is right after the syn. Ensure that run gate level simulation automatically after compilation box is turned off. In this tutorial, we will be using design architect to implement a nor gate shown below, and simulate it using. Navigate to the help pdf documentation pulldown menu and select tutorial from the list. Do not check the run gate level simulation automatically after compilation box. You can use this design example to learn how to perform gatelevel timing simulations of your design implemented in stratix ii devices with the cadence ncsim simulator. In gls, these force statements can be put into a file, and included in simulation.
Modelsim tutorial introduction modelsim is a simulation and debugging tool for vhdl, verilog, and mixedlanguage designs. Im trying to make a post gate level simulation for a pipelined processor. Quartus ii setup and use for the modelsim altera simulator. You should have working knowledge of the linux operating system using text editors, copying. We show how to perform functional and timing simulations of logic circuits implemented by using quartus prime cad software. A necessary evil part 1 rising complexity, tightening schedules and ever demanding time to market pressure are pushing the industry to move to the next level of abstraction for design representation viz esl electronic system level. Under eda netlist writer settings, in the format for output netlist list. The next slides showv tial compatiblev erilog model o f an xor gate and a d flip flop from the library. The increase in design sizes and the complexity of timing checks at 40nm technology nodes and below is responsible for longer run times, high memory requirements, and the need for a. It is a more complex type of simulation, where logic components and wires take some time to respond to input stimuli. Design files for this lesson the sample design for this lesson is a simple 8bit, binary upcounter with an associated testbench. Creating the working library in modelsim, all designs, be they vhdl, verilog, or some combination thereof, are compiled into a library.
So we need to tell quartus to generate the files needed by modelsim. Using modelsim to simulate logic circuits for altera fpga devices 1introduction this tutorial is a basic introduction to modelsim, a mentor graphics simulation tool for logic circuits. Treat xgobblers as sketchy engineers like to put xgobblers on their gate simulation models like rams, fuses, and plls because the ram model authors love to drive xs out of their ram. Quartus software tutorial developed for quartus eecs 270 at the university of michigan. Aug 31, 20 i write verilog code to model an inverter logic gate, compile that verilog code into a model whose behavior i can simulate, and simulate the behavior of that model, all within modelsim altera. Functional simulation and gate level simulation using. To run a gatelevel timing simulation using the nativelink feature. The implementation was the verilog simulator sold by gateway. The second step of the simulation process is the timing simulation. It is divided into fourtopics, which you will learn more about in subsequent. What i need are the proper way on creating a testbench for a gate level simulation. Gate level simulation methodology improving gate level simulation performance author.
For gatelevel simulation, the eda netlist writer generates a. Simulation a simulation is a computer model that mimics the operation of a real or proposed system and it is time based and takes into account all the resources and constr. You can simulate behavioral, rtl, and gate level code separately or simultaneously. All the device libraries required for this gate level simulation example come precompiled with the modelsim altera software. Design architect is a leading cadeda tool from mentor graphics. Generating a test bench with the alteramodelsim simulation tool. Although the circuit behaviour in verilog is normally specified using assignment statements, in some cases modeling the circuit using primitive gates is done to make sure that the critical sections of circuit is most optimally laid out. Custom flows support manual control of all aspects of simulation, including. Gate level simulation may take up to onethird of the simulation time and could potentially take most of the debugging time. Verilog simulator was first used beginning in 1985 and was extended substantially through 1987. Xl, which added a few features and implemented the infamous xl algorithm which was a very efficient method for doing gate. The increase in design sizes and the complexity of timing checks at 40nm technology nodes and below is responsible for longer. Gatelevel simulation with modelsim sepe simulator vhdl intel. For faster simulation, we can simulate the functionality of the memory without timing information behavioral mode.
This tutorial guide is an introduction to digital logic simulation and synthesis using the mentor graphics modelsim and precision rtl and xilinx ise and impact tools. Gatelevel simulation with modelsimaltera simulatorverilog hdl. For item 1 and 2, the flopslatchesrams should be forced to known value, either 0 or 1, before reset is done. This lesson provides a brief conceptual overview of the modelsim simulation environment. It is the most widely use simulation program in business and education. While we will be focusing on postplaceandroute gate level simulation in this tutorial, the same principles apply. You start a new simulation in modelsim by creating a working library called work.
Select gates from the dropdown list and click add node to add more gates. In the quartus software, in the processing menu, point to start and click start analysis and synthesis. What are the benefits of doing gate level simulations in vlsi. Modelsim fully supports current vhdl and verilog language standards. Cic training manual logic synthesis with design compiler, july, 2006. To simulate in modelsim, you will need to add an alteraspecific library containing models for the lpm memory that we generated above. Tutorial using modelsim for simulation, for beginners.
Gate level simulation is increasing trend tech trends. Using the menu tools, click on run eda simulation tool, and then click eda rtl simulation to automatically run the eda simulator, compile all necessary design files, and complete a simulation. On the tools menu, point to run eda simulation tool and click eda rtl simulation to automatically run the eda simulator, compile all necessary design files, and complete a simulation. Or we can simulate with full timing information for accurate results gate level mode. It is divided into four topics, which you will learn more about in subsequent lessons. Modelsim tutorial university of california, san diego. For gate level simulation, if you want to run simulation in modelsim automatically.
Then these new directories are created under the working directory, and the different modelsim output files. Quartus ii setup and use for the modelsimaltera simulator uio. Standard delay format sdf file of estimated delays. Virtuoso ams designer simulator tutorials november 2008 7 product version 8. Is there a tutorial here on how to do gate level simulations. Manual incremental compilation is more efficient because the compiler. Nov 27, 2011 please note although, gate level simulations take a lot of real time compare to rtl simulation, the time intervals in the test is the same. The problem is i have a 2 rams one for instructions. We will look at gate level simulations in a later class.
Cmos8hp in box library maps to, enter, or use the browse button to select. The tutorial was prepared using modelsim pe student edition running on windows 7. Gatelevel simulation with modelsim sepe simulator vhdl. It is run after rtl code is simulated and synthesized into a gate level netlist. For more information, please go to how to use quartus ii nativelink feature web page shows you the setting for the nativelink feature. Go to the tools menu, under eda simulation tool, click run eda gate level simulation. Not turn on run gate level simulation automatically. The method to handle item 1,2 is different from the way to handle item 3.
Using modelsim to simulate logic circuits for altera fpga. Creating gate level schematics and simulation design architect and eldo. Simulating altera ip in thirdparty simulation tools. Do not turn on run gate level simulation automatically. In this simulation design example, the gatelevel netlist multiplier. You can try implementing the above code in modelsim and try with your own set of inputs. Modelsimaltera and altera quartus ii setup by malik umar sharif, rabia shahid. Is gatelevel simulation still required nowadays verification horizons blog rss. To save the waveform as an image, click in the wayeform window, then click on file export image. The output directory should be simulation modelsim. Gatelevel simulation with modelsimaltera simulator. Repeat step 6 to place t wo level shifter not gates.
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