Tune Gain Parameter During Simulation

Step 1. Create a Simple Gain Model

If you would like to perform the example steps yourself, first create an example model.

The example model has a single gain block with a gain parameter that is tuned during simulation.

  1. Open the Simulink® Block Library and click Commonly Used Blocks.

  2. Add an Inport block.

  3. Add a Gain block. Double-click to open the block mask and change the value in the Gain parameter to gain.

  4. Add an Outport block.

  5. Connect all blocks as shown in the preceding diagram.

Step 2. Create Data Object for Gain Parameter

  1. Create a data object for the gain parameter:

    At the MATLAB® command prompt, type:

     gain = Simulink.Parameter
  2. Next, type:


    This command opens the property dialog box for the parameter object.

  3. Enter or select the following values:

    • Value: 2

    • Data type: double

    • Storage class: Model default

  4. Click OK.

For more information about using parameter objects for code generation, see Apply Storage Classes to Individual Signal, State, and Parameter Data Elements (Simulink Coder).

Step 3. Generate SystemVerilog DPI Component

  1. With the gain model open, select Simulation > Model Configuration Parameters.

  2. Click Code Generation.

  3. At System target file, click Browse and select systemverilog_dpi_grt.tlc.

    • If you have a license for Embedded Coder®, you can select target systemverilog_dpi_ert.tlc. This target allows you to access its additional code generation options (on the Code Generation pane in Model Configuration Parameters).

  4. At Toolchain, under Build process, select the toolchain you want to use from the list. See Generate Cross-Platform DPI Components for guidance on selecting a toolchain.

    You can optionally select flags for compilation. Under Build Configuration, select Specify from the drop-down list. Click Show Settings to display the current flags.

  5. In the Code Generation group, click SystemVerilog DPI.

  6. Leave both Generate test bench and Customize generated SystemVerilog code cleared (because this example modifies the generated SystemVerilog code, any test bench generated at the same time does not have the correct results).

  7. Click OK to accept these settings and to close the Configuration Parameters dialog box.

  8. In the example model, right-click the gain and delay blocks and select Create Subsystem from Selection. For this example, rename the subsystem dut.

  9. Right-click the subsystem and select C/C++ Code > Build this subsystem.

  10. In the Build code for subsystem dialog box, click Build.

    The SystemVerilog component is generated as dut_build/dut_dpi.sv in your current working folder.

Step 4. Add Parameter Tuning Code to SystemVerilog File

  1. Open the file dut_build/dut_dpi.sv and examine the generated code.

  2. In this example, after you call the initialize function, call the DPI_dut_setparam_gain function with the new parameter value. For example, here the gain is changed to 6:

    DPI_dut_setparam_gain(objhandle, 6);
  3. If the asynchronous reset signal is high (goes from 0 to 1), call Initialize again.

    if(reset == 1'b1) begin
        objhandle = DPI_dut_initialize(objhandle);
        DPI_dut_setparam_gain(objhandle, 6);
  4. The SystemVerilog code now looks like this:

    // File: dut_build\dut_dpi.sv
    // Created: 2015-01-21 13:58:40
    // Generated by MATLAB 8.5 and HDL Verifier 4.6
    `timescale 1ns / 1ns
    module dut_dpi(
        input clk,
        input clk_enable,
        input reset,
        input real dut_U_In1,
        output real dut_Y_Out1
        chandle objhandle=null;
        // Declare imported C functions
        import "DPI" function chandle DPI_dut_initialize(chandle existhandle);
        import "DPI" function void DPI_dut_output(input chandle objhandle, input real dut_U_In1, inout real dut_Y_Out1);
        import "DPI" function void DPI_dut_update(input chandle objhandle, input real dut_U_In1);
        import "DPI" function void DPI_dut_terminate(input chandle objhandle);
        import "DPI" function void DPI_dut_setparam_gain(input chandle objhandle, input real dut_P_gain);
        initial begin
            objhandle = DPI_dut_initialize(objhandle);
            DPI_dut_setparam_gain(objhandle, 6);
        always @(posedge clk or posedge reset) begin
            if(reset == 1'b1) begin
                objhandle = DPI_dut_initialize(objhandle);
                DPI_dut_setparam_gain(objhandle, 6);
            else if(clk_enable) begin
                DPI_dut_output(objhandle, dut_U_In1, dut_Y_Out1);
                DPI_dut_update(objhandle, dut_U_In1);

Step 5. Run Simulation with Parameter Change

To run your simulation, build the shared library and export the component, as explained in the following topics: