13. Generating C code with Simulink Coder

The Vortex DDS Blockset for Simulink supports Simulink Coder generation of C code, if you have a Simulink Coder license from MathWorks.

13.1. Prerequisites for C generation

In order to generate and compile C code containing DDS blocks, you must:

• Have Simulink Coder and MATLAB Coder installed and licensed from MathWorks.

• You have an appropriate C compile installed, as described by the MATLAB documentation.

• Vortex OpenSplice must be installed, and the appropriate release.com (Linux) or release.bat (Windows) script must have been executed in a command window.

• MATLAB must have been started from the same command window. You can check this by running the MATLAB command getenv('OSPL_HOME'). It should return a non-empty value.

• Your Simulink mode should execute correctly in simulation mode.

13.2. Preparing for C generation

Once your model has been validated via simulation mode, you are ready to generate and compile code. Because of an issue with the OpenSplice C99 language headers, you must manualy change the code generation options for your model. Follow these steps:

• From the model’s menu, choose Code > C/C++ Code > Code Generation Options.

• Click on the Code Generation tab in the left-hand pane.

• In the Build Configurations drop-down, choose Specify.

• In the table that appears below this, edit the Options value in the C Compiler row to remove the text $(ANSI_OPTS).

• Click OK or Apply to save your changes, then close the Code Generation Options dialog.

See the image, below, for an example of the code generation dialog.

C/C++ Code Generation Options. Remove the text $(ANSI_OPTS) for C Compiler to avoid compile errors.

A Simulink model without a Domain block and compiled with Simulink Coder will fail with a segmentation fault error if the Default parameter behavior is set to Inlined. The Inlined setting of Default parameter behavior is useful to reduce global RAM usage and increase efficiency of the generated code. But with this setting, the Simulink Coder does not generate code for all the blocks correctly.

To solve this problem you need to set the Default parameter behavior to Tunable.

Follow these steps:

• From your Simulink model, open Model Configuration Parameters dialog.

• Go to Optimization > Signals and Parameters or Code Generation > Optimization tab depending on Matlab version.

• Set the Default parameter behavior = Tunable.

• Click OK to save your changes, then save the model.

See the image, below, for an example of the Optimization dialog.

Set Default parameter behavior to Tunable to generate code correctly.

13.3. Generating code

At least from the Vortex DDS Blockset point of view, you are ready to generate code. Follow these steps:

• From the model’s menu, choose Code > C/C++ Code > Build Model.

• Simulink will get busy. You may see the following warnings in the Diagnostic View. These are OK, but are explained below.

Domain Participant Warning

A warning may appear about the domain participant block:

Source 'SimpleDomain/Domain/Participant_Entity ' specifies that its sample time (-1)
is back-inherited. You should explicitly specify the sample time of sources. You can
disable this diagnostic by setting the 'Source block specifies -1 sample time'
diagnostic to 'none' in the Sample Time group on the Diagnostics pane of the
Configuration Parameters dialog box.

Component:Simulink | Category:Blockwarning

As the message states, this is because the block specifies a sample time of -1. The block only creates meaningful output on initialization (it connects to DDS), so any inherited sample time is sufficient. Specifying a sample time of -1 allows the block to be place into a function-call subblock.

Full header search warning

The following warning about reverting to full header searches may appear:

The following error occurred while attempting to run the preprocessor to find the
minimum needed set of include files:

While parsing the source file '<path-to>/source/debug_utils.c' the following error
occurred

<path-to>/source/debug_utils.c:14: cannot open source file "os_stdlib.h"
|  #include "os_stdlib.h"
|                        ^

Reverting to full header search.

This may occur as you are trying to package code from compilation on another platform. The referenced header file is part of the OpenSplice distrubution. When you compile on another platform, you will need to have that platform’s OpenSplice distribution installed, and release variables set. The warning may be ignored.

Copy File information messages

If you are creating a source distrubution, you may see information messages such as the following:

cp: cannot stat ‘/libdcpsc99’: No such file or directory

The build is attempting to copy OpenSplice shared libraries (which are refered to via environment variables). These should not be copied by the build. Instead, when you compile the source on a target platform, these libraries will be found in the local OpenSplice installation.

13.4. Cross-compilation of models

If you are using Simulink Coder to cross-compile a model using the VortexDDS Block Set to a target other than environment in which you are running MATLAB, then the cross compilation needs access to:

• the OpenSplice HDE environment on the host, in order to obtain include files as well as libraries and executables required to run the VortexDDS block set. This is specified by the OSPL_HOME environment variable.

• the OpenSplice RTS environment for the target environment, in order to obtain libraries necessary to link your executables. This is specified by the LINK_OSPL_HOME environment variable.

During a Simulink Coder build, the VortexDDS Block Set will print a warning if the LINK_OSPL_HOME environment variable is set, indicating that it is appropriate only for cross-compilation. If you are performing both cross-compilations and host compilations, you must take care to set LINK_OSPL_HOME appropriately. For host compilations, you should clear LINK_OSPL_HOME.

13.5. Running built models

When you run a compiled Simulink executable, you will need:

• An appropriate OpenSplice runtime installation on the machine executing the model

• The correct OpenSplice environment variables, which are set by the release script in the installation root directory.