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Configure Variants for AUTOSAR Elements

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AUTOSAR software components can use VariationPoint elements to enable or disable AUTOSAR elements, such as ports and runnables, based on defined conditions. In Simulink®, to configure variants that enable or disable AUTOSAR ports and runnables:

  • Use Variant Sink and Variant Source blocks to define variant condition logic and propagate variant conditions.

  • Use AUTOSAR.Parameter data objects with storage class SystemConstant to model AUTOSAR system constants. The system constants represent the condition values that enable or disable ports and runnables. 

open_system('mAutosarInlineVariant.slx');

autosar_inlinevar_model.png

To model an AUTOSAR system constant, the model defines AUTOSAR.Parameter data object SysConA:

SysConA = AUTOSAR.Parameter;
SysConA.CoderInfo.StorageClass = 'Custom';
SysConA.CoderInfo.CustomStorageClass = 'SystemConstant';
SysConA.DataType = 'int32';
SysConA.Value = 1;

Each Variant Source or Variant Sink block defines variant condition logic, which is based on the system constant value. You can specify an expression or a Simulink.VariantExpression object containing an expression. Here is the variant condition logic for Variant Source block RunnableStepVP.

When you generate code for the model:

  • The exported ARXML code contains definitions for variation point proxies and variation points. In this example, the VARIATION-POINT-PROXY entry has a short-name c0, which is referenced in the generated C code. SysConA appears as a system constant representing the associated condition value. 

<VARIATION-POINT-PROXYS>
    <VARIATION-POINT-PROXY UUID="...">
        <SHORT-NAME>c0</SHORT-NAME>
        <CATEGORY>CONDITION</CATEGORY>
        <CONDITION-ACCESS BINDING-TIME="PRE-COMPILE-TIME">
          <SYSC-REF DEST="SW-SYSTEMCONST">/mInlineVariant_pkg/mInlineVariant_dt/SystemConstants/SysConA</SYSC-REF>
          == 0 ||
          <SYSC-REF DEST="SW-SYSTEMCONST">/mInlineVariant_pkg/mInlineVariant_dt/SystemConstants/SysConA</SYSC-REF>
          == 1</CONDITION-ACCESS>
    </VARIATION-POINT-PROXY>
</VARIATION-POINT-PROXYS>

VARIATION-POINT entries appear for AUTOSAR ports, runnables, and runnable accesses to external data. 

<R-PORT-PROTOTYPE UUID="...">
    <SHORT-NAME>In1</SHORT-NAME>
    <VARIATION-POINT>
        <SHORT-LABEL>In1_a3VP</SHORT-LABEL>
        <SW-SYSCOND BINDING-TIME="PRE-COMPILE-TIME">
          <SYSC-REF DEST="SW-SYSTEMCONST">/mInlineVariant_pkg/mInlineVariant_dt/SystemConstants/SysConA</SYSC-REF>
          == 0 ||
          <SYSC-REF DEST="SW-SYSTEMCONST">/mInlineVariant_pkg/mInlineVariant_dt/SystemConstants/SysConA</SYSC-REF>
          == 1</SW-SYSCOND>
    </VARIATION-POINT>
    ...
</R-PORT-PROTOTYPE>

  • In the RTE compatible C code, short-name c0 is encoded in the names of preprocessor symbols used in the variant condition logic. For example:

#if Rte_SysCon_c0
...
#endif

For more information, see Variant Systems.

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