modelsim simulation tutorial

ECE 4242/5242 Department of Electrical and Computer Engineering

Advanced Digital Design Methodology University of Colorado at Colorado Springs Fall Semester "Illuminate, Investigate, Innovate" Dr. Greg Tumbush, [email protected]

ModelSim Simulation Tutorial Page 1 of 3 Version 1.7

ModelSim/QuestSim Simulation Tutorial

1. Start ModelSim or the fully featured QuestaSim. There are many ways to access these

tools:

a. Download student version (ModelSim only) from

http://www.mentor.com/company/higher_ed/modelsim-student-edition

b. PCs in EN229, EN230, and 136.

c. Access through the windows server ClaaS. Instructions at

http://www.uccs.edu/~gtumbush/misc/QuestaSim_ClaaS.pdf (once certificate errors

are resolved). Until certificate errors are resolved access ClasS via

https://claas1.uccs.edu/portal/webclient/index.html. Ignore certificate warnings. You

will need to be connected to the UCCS Resources VPN (Voyager).

d. Access through the linux server LATS1.

i. From Windows 7 instructions at

http://www.uccs.edu/~gtumbush/misc/accessing_lats1.pdf

ii. From Windows 8 instructions at http://www.uccs.edu/~gtumbush/misc/LATS-

HowToSetup.pdf

iii. You will need to be connected to the UCCS Resources VPN (Voyager).

2. Create a new project

a. Create a directory called Add_half in your workspace using Windows Explorer

(windows) or mkdir (Linux).

b. Click on File->New->project

c. In pop-up window fill in the Project Name field (ex: Add_half)

d. Click on Browse to create the project in the desired location. (ex:

Z:/Data/4242/Add_half)

e. Click on OK

3. Add files

a. In Add items to the Project pop-up click on Add Exiting File or Create New File.

Since Im creating Add_half from scratch Ill click on Create New File.

b. Fill in the File Name field (ex Add_half) and in the Add file as type pull-down

select verilog. The correct file extension will be added. Click on OK

c. Click on Close

4. In the Project tab of the main modelsim window double click on Add_half.v. The file will

open in an editor. If you wish undock the editing window by clicking on . in the editor

window. Type in the following data:


Advanced Digital Design Methodology University of Colorado at Colorado Springs Fall Semester "Engineering for the Future"


5. Click on File->Save in either the main modelsim window or the undocked editor window.

6. In main modelsim window click on Compile->Compile All. In the transcript window you

should see Compile of Add_half.v was successful. If not fix any syntax errors.

7. Simulate

a. In the Transcript window type vsim novopt Add_half. In the transcript

window you should see # Loading work.Add_half

b. In the main modelsim window Click on View->Wave

c. In the Workspace window make sure the Sim tab is selected and click on

Add_half. This will show you all the signals at the Add_half level of hierarchy in

the Objects window.

d. Select all the signals in the Objects window and drag them to the wave window.

e. In the Transcript window type run 10ns

f. In the wave window click on View->Zoom->Zoom Full if the wave window is

undocked or type F. Note that your inputs are Z and outputs are X. This is

because the inputs are not driven. The wave window can be undocked by

clicking on the . button on the upper right hand side of the wave window.

g. In the Transcript window type the following

h. You should see signal a being driven to a 0, signal b being driven to a 1, and

the expected output is c_out = 0 and sum = 1.

8. To restart a simulation type in the Transcript window quit sim

9. To quit modelsim click on File->Quit

10. To open up an existing project do one of the following:

a. Start Modelsim, click on File->Open, in the Open File dialog box select Project

Files (*.mpf) in the Files of Type pull-down, select the project and click Open.

b. Browse to the location you specified in step 2 and double click on the project.

11. Notes:

force a 0

force b 1

run 10ns

// Definition of a half adder using primitives

module Add_half (input a, b, output sum, c_out);

xor (sum,a,b);

and(c_out,a,b);

endmodule


Advanced Digital Design Methodology University of Colorado at Colorado Springs Fall Semester "Engineering for the Future"


a. You must add signals before running the simulation or else the simulator will not

collect the data for you.

b. If you recompile any code or add signals to the waveform and want to re-run

type the following:

i. quit sim

ii. vsim novopt Add_half

iii. add your signals

iv. run

modelsim simulation tutorial

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