To restart and re-run the simulation, click the “RestartSimulation” button at the top of the console window. By default, Modelsim will onlyrecord data for the signals that have been added to the waveform window before or during the simulation.Therefore, when new signals are added to the waveform window, the simulation needs to be restartedand re-run for the desired amount of time. This isbecause Modelsim did not record the simulation data for these signals. When you addnew signals to the wave window, you will notice that waveforms do not automatically appear. You can drag and drop them fromthe signals window, or highlight them in the signals window and then select Add Wave Selected Signals.If you use this second technique, you will see that there are additional options available. Figure 50: Simulated waveformsThere are two basic methods for adding signals to the wave window. Additionalsignals are displayed in the signal window based upon the selected structure in the structure window. ProjectNavigator automatically adds all top-level signals to the wave window, as shown in Figure 50. 49įigure 49: Modelsim Signals WindowThe fourth and final window is the wave window, which is used to display simulated waveforms. This window shows the signals that arepresent in the portion of the design selected in the structure window. Figure 48: Modelsim Structure WindowThe third window is the signals window, shown in Figure 49. In large hierarchical designs, it is very handy. This window allows you to browse thehierarchy of the test bench and the design under test. 48įigure 47: Modelsim Console WindowThe second window is the structure window, shown in Figure 48. You should see text output from the test bench. These messages include notes, warnings, and errors,plus any output created by the design being simulated. The first, and most important, is the main Modelsim console, shown in Figure 47.This window displays messages from the simulator. Modelsim creates a work directory,compiles the source files, loads the design, and performs simulation for the time specified. Click “Ok”.To start the simulation, double-click Simulate Behavioral Model. For test benches that require moresimulation time, this property should be adjusted as needed. The most interesting of these parameters is probably the simulation runtime – 1000 ns is more than sufficient for the test bench in the project. Make sure the propertiesare set as shown in Figure 46. Select the Processes tab, set theProperty Display Level to advanced, and then return to Simulation Properties. 47įigure 46: Simulation Process PropertiesIf you do not have all the properties shown in Figure 46, you can make them visible by canceling thedialog box, then selecting Edit Preferences from the main menu. The Process Properties dialog box appears, as shown in Figure 46. Right click on Simulate Behavioral Model, and selectSimulation Properties. Simulates the netlist after Place & Route.At this point, you will perform a functional simulation using Simulate Behavioral Model but you mustspecify the simulation process properties first. Simulate Post-Place & Route Verilog Model.Simulates the netlist after the Map stage.
Simulates the netlist after the NGDBuild stage.
This process will start the design simulation. The following simulation processes are available:
Next to theModelsim Simulator entry in the Processes for Current Source window to expand the item, this is alsoshown in Figure 45.