Main Content

Improve Code Readability of Variant Parameters Using Enumerated Types

You can use enumerated types to improve code readability of variant control values in variant parameters. Simulink Enumerations improve readability because enumerated types of variant controls values are represented as meaningful names instead of integers in the generated code.

You can define enumerated types of variant control values in the storage locations listed in Storage Locations for Variant Control Variables (Operands) in Variant Parameters.

For variant parameters with startup activation time, only enumerations that are defined using these techniques are supported:

  • By subclassing built-in integer data types int8, int16, int32, uint8, or uint16, or by subclassing Simulink.IntEnumType

These enumerations are also supported when permanently stored in a Simulink® data dictionary. See Enumerations in Data Dictionary.

Model

Open the model slexVariantSubsystemsAndParametersWithStartup.

open_system('slexVariantSubsystemsAndParametersWithStartup')

This model represents a fog lamp controller system that operates in driver control mode and in sensor connected mode. In driver control mode, the intensity of the fog lamps is controlled by the driver. In sensor connected mode, the sensor adjusts the intensity of different types of fog lamps based on the intensity of ambient light in the external environment.

In this example, lightVolt is a variant parameter that represents fog lamp intensities. The sensor voltage from Signal Builder block is the intensity of ambient light in the external environment. The LIGHT_TYPE is the variant control variable that represents different types of fog lamps. LIGHT_TYPE enables you to switch between fog lamp intensities, lightVolt, for the given intensity of ambient light. LIGHT_TYPE can have two values, LightType.Type1 and LightType.Type2.

When LIGHT_TYPE == LightType.Type1 evaluates to true, a fog lamp intensity from [0 0 0 0.7 0.7] that corresponds to the given ambient light becomes active. When LIGHT_TYPE == LightType.Type2 evaluates to true, a fog lamp intensity from [0 0 0 1 1] that corresponds to the given ambient light becomes active. For example, if the ambient light has an intensity 4 and the type of the fog lamp is Type1, the fog lamp is illuminated with intensity 0.7. Similarly, if the ambient light has an intensity 4 and the type of the fog lamp is Type2, the fog lamp is illuminated with intensity 1. For more information on this fog lamp controller system, see Run Iterative Simulations Without Recompiling Model for Variant Systems Using Fast Restart.

Fog Lamp Types in a Enumeration Class

In this example, the enumeration LightType, saved in LightType.m, derives from the built-in class Simulink.IntEnumType. It defines two enumeration members, Type1 and Type2, with underlying integer values 1 and 2.

type LightType.m
classdef LightType < Simulink.IntEnumType
% ControllerType - enumeration class used by
% slexVariantSubsystemsAndParametersWithStartup
    
% Copyright 2021-2022 The MathWorks, Inc.
   
    enumeration
        Type1 (1)
        Type2 (2)
    end
    
    methods (Static)
        function val = getDataScope()
            val = 'Imported';            
        end
        
        function val = getHeaderFile()
            val = 'LightType.h';
        end
    end
end

Simulate Fog Lamp Controller for Different Types of Fog Lamps in Sensor Connected Mode

1. In the MATLAB® Command Window:

a. Set CTRL_MODE to 1 to activate the Sensors Connected.

CTRL_MODE.Value = int32(1)
CTRL_MODE = 

  Parameter with properties:

          Value: 1
      CoderInfo: [1x1 Simulink.CoderInfo]
    Description: ''
       DataType: 'int32'
            Min: []
            Max: []
           Unit: ''
     Complexity: 'real'
     Dimensions: [1 1]


b. Set LIGHT_TYPE to LightType.Type1 to represent Type1 type of fog lamps.

LIGHT_TYPE.Value = LightType.Type1
LIGHT_TYPE = 

  VariantControl with properties:

             Value: Type1
    ActivationTime: 'startup'

Check that the activation time of the LIGHT_TYPE is set to startup.

2. Run the simulation. Use the Scope block to visualize the results. For details about the signals that the Scope block plots, see the Model Inputs and Outputs section of Run Iterative Simulations Without Recompiling Model for Variant Systems Using Fast Restart.

3. Change the value of LIGHT_TYPE to LightType.Type2 and run the simulation again. Use the Scope to visualize the results.

LIGHT_TYPE.Value = LightType.Type2
LIGHT_TYPE = 

  VariantControl with properties:

             Value: Type2
    ActivationTime: 'startup'

Generate Code for Enumerated Type of fog lamps

Before you generate code from the model, make sure that you have write permission in your current folder.

To generate code using Simulink® Coder™, the configuration parameters in Model Settings > Code Generation are set as:

1. The System target file is specified as grt.

2. On the Custom Code pane, the header file is specified as ReadLightControllerValues.h and the source file is specified as ReadLightControllerValues.c. This setting inserts the ReadLightControllerValues() function in the model source file, slexVariantSubsystemsAndParametersWithStartup.c, of the generated code.

3. In the Apps gallery of the model toolstrip, click Simulink Coder. On the C Code tab, click Generate Code. For more information, see Generate Code Using Simulink Coder (Simulink Coder).

slbuild('slexVariantSubsystemsAndParametersWithStartup')
### Starting build procedure for: slexVariantSubsystemsAndParametersWithStartup
### Successful completion of build procedure for: slexVariantSubsystemsAndParametersWithStartup

Build Summary

Top model targets built:

Model                                          Action                       Rebuild Reason                                    
==============================================================================================================================
slexVariantSubsystemsAndParametersWithStartup  Code generated and compiled  Code generation information file does not exist.  

1 of 1 models built (0 models already up to date)
Build duration: 0h 0m 21.698s

Review Generated Code

1. In the C Code tab, select Open Report.

2. From the Generated Code pane of the report,select the slexVariantSubsystemsAndParametersWithStartup.c file. The slexVariantSubsystemsAndParametersWithStartup_intialize function contains the ReadLightControllerValues() function to read the values of CTRL_MODE and LIGHT_TYPE for determining the mode of operation and the type of the fog lamp. The value of LIGHT_TYPE read using the function is compared to the enumerated names Type1 and Type2 that maps to the values 1 and 2 of the enumeration LightType. Based on the condition that evaluates to true, the set of fog lamp intensities to activate is determined.

void slexVariantSubsystemsAndParametersWithStartup_initialize(void)
{
...
 /* user code (Initialize function Body) */
   /* System '<Root>' */
   ReadValueOfVariantControls();
   /* Variant Parameters startup activation time */
   if (LIGHT_TYPE == Type1) {
     for (i = 0; i < 5; i++) {
       slexVariantSubsystemsAndParam_P.lightVolt[i] = (real_T)tmp[i];
     }
   } else if (LIGHT_TYPE == Type2) {
     for (i = 0; i < 5; i++) {
       slexVariantSubsystemsAndParam_P.lightVolt[i] = tmp_0[i];
     }
   }
...
}

See Also

Enumerated Types to Improve Code Readability of Variant Control Variables of Variant Parameters