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Generate HDL Code from Simulink Model from Command Line

You can customize and edit HDL code generation options and then generate code at the command line. This example illustrates how you can use the Configuration Parameters dialog box to generate HDL code for the Symmetric FIR filter model.

FIR Filter Model

Before you generate HDL code, the model must be compatible for HDL code generation. To check and update your model for HDL compatibility, see Check HDL Compatibility of Simulink Model Using HDL Code Advisor. You can also customize the model parameters by using the hdlsetup function.


This example uses the Symmetric FIR filter model that is compatible for HDL code generation. To open this model at the command line, enter:


The model uses a division of labor that is suitable for HDL design.

  • The symmetric_fir subsystem, which implements the filter algorithm, is the device under test (DUT). An HDL entity is generated from this subsystem.

  • The top-level model components that drive the subsystem work as a test bench.

The top-level model generates 16-bit fixed-point input signals for the symmetric_fir subsystem. The Signal From Workspace block generates a test input (stimulus) signal for the filter. The four Constant blocks provide filter coefficients. The Scope blocks are used for simulation and are not used for HDL code generation.

To navigate to the symmetric_fir subsystem, enter:


Symmetric FIR filter algorithm.

Create a Folder and Copy Relevant Files


  1. Create a folder named sl_hdlcoder_work, for example:

    mkdir C:\work\sl_hdlcoder_work

    sl_hdlcoder_work stores a local copy of the example model and folders and generated HDL code. Use a folder location that is not within the MATLAB folder tree.

  2. Make the sl_hdlcoder_work folder your working folder, for example:

    cd C:\work\sl_hdlcoder_work
  3. Save a local copy of the sfir_fixed model to your current working folder. Leave the model open.

Generate HDL Code

To generate HDL code for the DUT, you use the makehdl function. For example, to generate HDL code for the symmetric_fir subsystem, enter:


To specify the customizations before you generate HDL code, use the hdlset_param function. You can also specify various name-value pair arguments with the makehdl function to customize HDL code generation options while generating HDL code. For example, to generate Verilog code, use the TargetLanguage property.

makehdl('sfir_fixed/symmetric_fir', 'TargetLanguage', 'Verilog')
Alternatively, if you are using hdlset_param, set this parameter on the model and then run the makehdl function.
hdlset_param('sfir_fixed', 'TargetLanguage', 'Verilog')

HDL Coder™ compiles the model before generating code. Depending on model display options such as port data types, the model can change in appearance after code generation. As code generation proceeds, HDL Coder displays progress messages in the MATLAB command line with:

  • Link to the Configuration Set that indicates the model for which the Configuration Parameters are applied.

  • Links to the generated files. To view the files in the MATLAB Editor, click the links.

    • symmetric_fir.vhd: VHDL code. This file contains an entity definition and RTL architecture implementing the symmetric_fir.vhd filter.

    • Mentor Graphics® ModelSim® compilation script (vcom command) to compile the generated VHDL code.

    • symmetric_fir_synplify.tcl: Synplify® synthesis script.

    • symmetric_fir_map.txt: This report maps generated entities to the subsystems that generated them. See Trace Code Using the Mapping File

The process completes with the message:

### HDL Code Generation Complete.

See Also


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