1. In your current folder, create the file ex_cc_simpleTypes.h.

   typedef enum {
     PWR_LOSS = 0,                 /* Default value */
     OVERSPD,
     PRESS_LOW,
   } fault_T;
   
   typedef struct {
       double coeff;
       double init;
   } params_T;

2. Generate Simulink representations of the types by calling Simulink.importExternalCTypes.

   Simulink.importExternalCTypes('ex_cc_simpleTypes.h');

   The function creates a Simulink.Bus object, params_T, in the base workspace.

3. To inspect the properties of the object, open the Bus Editor.

   buseditor

   Each bus element uses a name and a data type (double) that match the corresponding structure field in ex_cc_simpleTypes.h.

4. In your current folder, inspect the generated file, fault_T.m, which defines the enumerated type fault_T as an enumeration class.

   You can use the bus object and the enumeration class to set signal and parameter data types in Simulink models.

This example shows how to generate a Simulink representation of a structure type whose fields use custom data types (typedef).

Create the file ex_integer_aliases.h in your current folder.

typedef int sint_32;

typedef unsigned short uint_16;

Create the file ex_cc_struct_alias.h in your current folder.

#include "ex_integer_aliases.h"

typedef struct {
    sint_32 accum;
    uint_16 index;
} my_ints_T;

Import the structure type into Simulink as a Simulink.Bus object in the base workspace. Import the typedef statements as Simulink.AliasType objects.

Simulink.importExternalCTypes('ex_cc_struct_alias.h');

Inspect the data types of the bus elements in the bus object. For example, inspect the DataType property of the first bus element, which corresponds to the structure field accum.

my_ints_T.Elements(1)

ans = 

  BusElement with properties:

              Name: 'accum'
        Complexity: 'real'
        Dimensions: 1
          DataType: 'sint_32'
               Min: []
               Max: []
    DimensionsMode: 'Fixed'
        SampleTime: -1
              Unit: ''
       Description: ''

The Simulink.importExternalCTypes function uses the generated Simulink.AliasType objects to set the data types of the bus elements.

Inspect the Simulink.AliasType objects in the base workspace. For example, the object named sint_32 corresponds to one of the typedef statements in ex_integer_aliases.h.

sint_32

sint_32 = 

  AliasType with properties:

    Description: ''
      DataScope: 'Imported'
     HeaderFile: 'ex_integer_aliases.h'
       BaseType: 'int32'

For most host computers (which the function targets by default), the word length of int is 32 bits and the word length of unsigned short is 16 bits. The function maps int and unsigned short to the Simulink types int32 and uint16.

If you have Embedded Coder, the code that you generate from the model can use sint_32 and uint_16 instead of the standard data type names, int32_T and uint16_T.

This example shows how to store the imported data types in a Simulink data dictionary. A data dictionary stores data specifications (such as for signals and block parameter values), data types, and other design data for one or more Simulink models.

In your current folder, create the file ex_cc_simpleTypes.h.

typedef enum {
  PWR_LOSS = 0,            /* Default value */
  OVERSPD,
  PRESS_LOW,
} fault_T;

typedef struct {
    double coeff;
    double init;
} params_T;

Create a subfolder called myDictionaries.

mkdir('myDictionaries')

Generate Simulink representations of the types by calling Simulink.importExternalCTypes. Permanently store the type definitions by creating a new data dictionary, ex_cc_myTypes.sldd, in the new subfolder.

Simulink.importExternalCTypes('ex_cc_simpleTypes.h',...
    'DataDictionary','ex_cc_myTypes.sldd',...
    'OutputDir','myDictionaries');

To inspect the contents of the dictionary, set your current folder to myDictionaries and double-click the dictionary file.

To use the Simulink representations in the dictionary, you must link a model or models to the dictionary. See Migrate Models to Use Simulink Data Dictionary.

This example shows how to generate Simulink representations only for enumerated and structure data types that you identify by name.

In your current folder, create the file ex_cc_manySimpleTypes.h. The file defines three structure types: params_T, signals_T, and states_T.

typedef struct {
    double coeff;
    double init;
} params_T;

typedef struct {
    double flow_rate;
    double steam_press;
} signals_T;

typedef struct {
    double accum;
    double error;
} states_T;

Generate Simulink representations only for params_T and signals_T.

Simulink.importExternalCTypes('ex_cc_manySimpleTypes.h',...
    'Names',{'params_T','signals_T'});

The Simulink.Bus objects, params_T and signals_T, appear in the base workspace.

By default, Simulink.importExternalCTypes represents an enumerated data type by creating an enumeration class that derives from the built-in class Simulink.IntEnumType. When you simulate or generate code from a model that uses the generated class, configuration parameters that you select for the model (for example, on the Hardware Implementation pane) determine the specific integer length that Simulink.IntEnumType and the enumeration class employ.

By default, the function interprets generic, primitive C data types, such as short and int, according to the word lengths of your host computer. For example, to represent an int structure field, the function typically applies the 32-bit data type int32 to the corresponding bus element. When you want to simulate and generate code for hardware other than your host computer, use the HardwareImplementation pair argument to identify the target hardware and, by extension, the word lengths of the hardware.

This example shows how to import data types from code that you intend to use on 16-bit hardware. For this board, int has a 16-bit length, and each item of enumerated data (enum) consumes 16 bits.

In your current folder, create the file ex_cc_intTypes.h.

typedef enum {
  PWR_LOSS = 0,            /* Default value */
  OVERSPD,
  PRESS_LOW,
} fault_T;

typedef struct {
    int coeff;
    int init;
} params_T;

The code defines an enumerated data type and a structure type whose fields use the generic C data type int.

To generate an accurate Simulink representation of the structure type, first open an existing model or create a new model. For this example, create a new model named ex_hdwImpl_16bit.

In the new model, set Configuration Parameters > Hardware Implementation > Device vendor to Atmel. Set Device type to AVR.

Alternatively, at the command prompt, use these commands to create and configure the model:

new_system('ex_hdwImpl_16bit','Model');
set_param('ex_hdwImpl_16bit','ProdHWDeviceType','Atmel->AVR')

Generate Simulink representations of the types. To specify the word lengths of the target 16-bit hardware, extract the model configuration parameters (which include the Hardware Implementation settings) as a Simulink.ConfigSet object.

configSet = getActiveConfigSet('ex_hdwImpl_16bit');
Simulink.importExternalCTypes('ex_cc_intTypes.h','HardwareImplementation',configSet);

The Simulink.Bus object params_T appears in the base workspace. The bus elements, such as coeff, use the Simulink data type int16.

params_T.Elements(1)

ans = 

  BusElement with properties:

              Name: 'coeff'
        Complexity: 'real'
        Dimensions: 1
          DataType: 'int16'
               Min: []
               Max: []
    DimensionsMode: 'Fixed'
              Unit: ''
       Description: ''

In your current folder, the file fault_T.m defines the enumeration class fault_T. The class derives from Simulink.IntEnumType, so you must use model configuration parameters to identify the target hardware and, by extension, the correct native integer length.

Create the file ex_cc_fixpt_struct.h in your current folder.

typedef struct {
    
    int coeff;   /* Word length 16, 
       binary fraction length 7 */
    
    int init;   /* Word length 16, 
       binary fraction length 3 */
    
} params_T;

The file defines a structure type whose fields use fixed-point data types. For example, the structure stores the field coeff in a signed, 16-bit integer data type. A binary fraction length of 7 relates the stored integer value to the real-world value.

Suppose that this code operates on 16-bit hardware (such that the generic C data type int has a 16-bit word length). To generate a Simulink representation of the type, first create a coder.HardwareImplementation object that identifies the hardware.

hdw = coder.HardwareImplementation;
hdw.ProdHWDeviceType = 'Atmel->AVR';

Generate a Simulink representation of the structure type.

Simulink.importExternalCTypes('ex_cc_fixpt_struct.h',...
    'HardwareImplementation',hdw);

The Simulink.Bus object, params_T, appears in the base workspace. Each bus element, such as coeff, uses the data type int16.

params_T.Elements(1)

ans = 

  BusElement with properties:

              Name: 'coeff'
        Complexity: 'real'
        Dimensions: 1
          DataType: 'int16'
               Min: []
               Max: []
    DimensionsMode: 'Fixed'
              Unit: ''
       Description: ''

Simulink.importExternalCTypes cannot infer the fixed-point scaling (binary fraction length) from the C code. You must manually specify the data types of the bus elements. To specify the data types at the command prompt, use the fixdt function.

params_T.Elements(1).DataType = 'fixdt(1,16,7)';
params_T.Elements(2).DataType = 'fixdt(1,16,3)';

To specify the data types interactively (by using the Data Type Assistant), use the Bus Editor.

buseditor

Import Custom C Types

Create the file ex_cc_myTypes_rec.h in your current folder. The file defines a custom structure type.

typedef struct {
    double flow;
    double pres;
    double tqe;
} sigStructType;

Generate a Simulink.Bus object that represents the type.

Simulink.importExternalCTypes('ex_cc_myTypes_rec.h');

Modify Type Definition in C Code

In ex_cc_myTypes_rec.h, add a field named spd to sigStructType.

In the same file, create a new structure type, stateStructType.

typedef struct {
    double flow;
    double pres;
    double tqe;
    double spd;
} sigStructType;

typedef struct {
    double err;
    double read;
    double write;
} stateStructType;

Attempt to Import Types Again

Attempt to generate bus objects that represent the types.

importInfo = Simulink.importExternalCTypes('ex_cc_myTypes_rec.h');

The function generates warnings at the command prompt. Instead of relying on the warnings, you can inspect the output, importInfo, to determine whether the function failed to import any types.

importInfo.failedToImport.Bus

ans =

  1×1 cell array

    {'sigStructType'}

The function did not import sigStructType. The corresponding bus object in the base workspace still has only three bus elements. To determine the reason that the function did not import sigStructType, inspect the report field of importInfo.

Import sigStructType again. This time, overwrite the existing bus object.

importInfo = Simulink.importExternalCTypes('ex_cc_myTypes_rec.h',...
    'Names',importInfo.failedToImport.Bus,'Overwrite','on');

When you overwrite existing Simulink representations, any customizations that you made to the Simulink representations (such as the application of fixed-point data types to bus elements) are overwritten.