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Configure Generated Code According to Interface Control Document Specifications

This example shows how to configure code generation settings for a model according to specifications in an interface control document (ICD). The example also shows how to store shared Simulink variables and data objects in a data dictionary.

An ICD describes the data interface between software components. To exchange and share data, the components declare and define global variables that store signal and parameter values according to the ICD. The ICD names the variables and lists characteristics such as data type, physical units, and parameter values. When you create component models in Simulink, you can configure the models such that the generated code conforms to the ICD. For example, you can use the ICD as a reference source while configuring models interfactively or you can automate configuraiton by using a script to import data from an ICD.

Explore Interface Control Document

In Microsoft® Excel® or another compatible program, open the ex_ICD_PCG.xlsx workbook and review the contents of the worksheets.

open ex_ICD_PCG.xlsx
  • Signals worksheet. Each row represents a signal that crosses the interface boundary. Inspect the cell values in the worksheet. The Owner column identifies the name of the component that allocates memory for a signal. The DataType column names the signal data type in memory. For example, the worksheet uses the expression Bus: EngSensors to name the structure type EngSensors.

  • Parameters worksheet. The Value column lists the value of each parameter. If the value of a parameter is nonscalar, the value is stored in its own separate worksheet, which has the same name as the parameter.

  • Numeric Types worksheet. Each row represents a named numeric data type. In this ICD, the data uses fixed-point data types (Fixed-Point Designer). The IsAlias column indicates whether the C code uses the name of the data type (for example, s16En3) or uses the name of the primitive integer data type that corresponds to the word length (such as short). The DataScope column indicates whether the generated code exports or imports the data type definition.

  • Structure Types worksheet. Each row represents a structure type or a field of a structure type. For structure types, the value in the DataType column is struct. Subsequent rows that do not use struct represent fields of the preceding structure type. This ICD defines structure type, EngSensors, with four fields: throttle, speed, ego, and map.

  • Enumerated Types worksheet. Similar to the Structure Types worksheet, each row represents an enumerated type or an enumeration member. This ICD defines enumerated type sldemo_FuelModes.

Explore External Code

Some data items in the ICD belong to other_component, which is a component that exists outside of MATLAB. Open and explore the content of these example files, which define and declare the external data:

edit ex_inter_types.h
edit ex_inter_sigs.c
edit ex_inter_sigs.h

Explore Example Model

In this example, you generate code from the controller model rtwdemo_fuelsys_dd_controller. Open your copy of the model.

open_system('rtwdemo_fuelsys_dd_controller')

Some signals in the controller model have names, for example, the input signal sensors. Some block parameters in the model refer to Simulink.Parameter objects in a data dictionary. For example, in the airflow_calc subsystem, the Pumping Constant block uses the parameter objects PumpCon, SpeedVect, and PressVect. These parameter objects set the values of the corresponding block parameters. You can apply code generation settings to the signals and parameter objects.

The controller model is linked to data dictionary rtwdemo_fuelsys_dd_controller.sldd. Explore the data dictionary.

  1. In the lower-left corner of the controller model, click the model data badge.

  2. Click the External Data link.

  3. In the Model Explorer Model Hierarchy pane, expand the nodes rtwdemo_fuelsys_dd_controller, External data, and rtwdemo_fuelsys_dd_controller.

  4. Select Design Data.

The dictionary stores:

  • Parameter objects

  • Simulink.NumericType objects, such as u8En7

  • Simulink.Bus object, EngSensors

Configure Model Design Data According to ICD

  1. Open the ICD spreadsheet, if not open already.

  2. In the Simulink Editor window for the controller model, navigate to the root level of the model.

  3. On the Modeling tab, click Model Data Editor.

  4. In the Model Data Editor, click the Change scope button. The Model Data Editor shows information about data items in the model subsystems.

  5. Click the Show/refresh additional information button. The Model Data Editor shows information about data objects (the Simulink.Parameter objects in the data dictionary) that the model uses.

Configure Design Settings for Signals

  1. In the ICD, click the Signals tab.

  2. In the Model Data Editor, click the Inports/Outports tab.

  3. Make sure that the configuration settings for Inport block sensors matches the ICD specification. Data Type must be set to Bus: EngSensors.

  4. Make sure that the configuration settings for Outport block fuel_rate match the ICD specification. Data Type must be set to s16En7. Min must be set to 0.8000. Max must be set to 1.7000. Unit must be set to g/s.

  5. Make sure that the configuration settings for signal fuel_mode match the ICD specification. Because fuel_mode is an output signal of a Stateflow chart, you must use Model Explorer to configure the design settings. In the model, navigate into the Stateflow chart. Open Model Explorer. In the Model Explorer Contents pane (the middle pane), select fuel_mode. Data Type must be set to Enum:sld_FuelModes.

Configure Design Settings for Parameters

  1. In the ICD, click the Parameters tab.

  2. Navigate to the root level of the control model.

  3. In the Model Data Editor, click the Parameters tab.

  4. Use the Filter contents box to search for parameter PressEst. The Model Data Editor shows two rows: one row that corresponds to parameter object PressEst and one row that corresponds to the block parameter that uses PressEst.

  5. Make sure that the configuration settings for parameter PressEst match the ICD specification. Data Type must be u8En7. Value must be a 19x45 matrix of numeric values.

  6. Make sure that the Data Type and Value settings for parameters PumpCon, SpeedEst, ThrotEst, and RampRateKiz match the ICD specification.

Configure Design Settings for Numeric Types

  1. In the ICD, click the Numeric Types tab.

  2. If the Model Explorer is not open, open it.

  3. In the Model Hierarchy pane, navigate to the design data in the data dictionary for the controller model (rtwdemo_fuelsys_dd_controller> External Data>rtwdemo_fuelsys_dd_controller>Design Data).

  4. In the Contents (middle) pane, select the Simulink.NumericType object u8En7. This object represents one of the typedef statements in ex_inter_types.h.

  5. In the right pane, on the Design tab, confirm that the setting for Data type mode aligns with the ICD specification.

  6. Make sure that the design configuration for numeric types s16En3, s16En7, and s16En15 matches the ICD specification.

Configure Design Settings for Structures

  1. In the ICD, click the Structure Types tab.

  2. In the Model Explorer Contents pane, select EngSensors. This Simulink.Bus object represents the structure type defined in ex_inter_types.h.

  3. Confirm that the data type configuration aligns with the ICD specification. In the right pane, on the Design tab, or in the Bus Editor, adjust the bus signal configurations (for example, settings for Min and Max) to align with the ICD specification.

Configure Design Settings for Enumerated Types

  1. In the ICD, click the Enumerated Types tab.

  2. Open the file sld_FuelModes.m, which defines the class for the enmerated type sld_FuelModes.

  3. Confirm that the class definitnion aligns with the ICD specification. In the file sld_FuelModes.m, adjust member names and underlying integer values to align with the ICD specification.

Configure Model for Code Generation According to ICD

  1. Open the ICD spreadsheet, if not open already.

  2. Open the Embedded Coder app.

Configure Code Generation Settings for Inport and Outport Blocks

  1. In the ICD, click the Signals tab. The Owner column in the ICD implies that a different component (other_componnent), not rtwdemo_fuelsys_dd_controller, provides the code definition of the sensors variable.

  2. Include the C source code file that defines the variable sensors. In the Simulink Editor, on the C Code tab, select Settings> C/C++ Code generation settings. Make sure that the code generation custom code parameter Source files is set to ex_inter_sigs.c.

  3. In the Simulink Editor, on the C Code tab, select Code Interface> Individual Element Code Mappings.

  4. In the Code Mappings editor, click the Inports tab.

  5. Select the row for sensors. Because the source code definition is provided in the external file ex_inter_sigs.c, which you configured in step 2, Storage class must be set to ImportFromFile.

  6. Click the icon. Check that the HeaderFile property setting matches the ICD specification, ex_inter_sigs.h. Make sure that a value is specified for the Identifier property. This property specifes the variable name for the data element in the generated code.

  7. In the Code Mappings editor, click the Outports tab.

  8. Select the row for fuel_rate. Because the ICD specifies rtwdemo_fuelsys_dd_controller as the owner of fuel_rate, Storage Class must be set to ExportToFile.

  9. Click the icon. Make sure that the settings for properties HeaderFile, DefinitionFile, and Owner match the ICD specifications global_data.h, signals.c, and rtwdemo_fuelsys_dd_controller, respectively. Make sure that a value is specified for the Identifier property.

Configure Code Generation Settings for Signals

  1. In the Code Mappings editor, click the Signals/States tab. The third signal listed on the Signals tab of the ICD is fuel_mode.

  2. Add the fuel_mode signal to the model code mappings. In the model diagram, select signal fuel_mode. Place your cursor on the ellipsis that appears above or below the signal line to open the action bar. Click the Add selected signals to code mappings button. In the Code Mappings editor, the Signals node expands and lists the signal that you added. The Storage Class setting must indicate that the signal resolves to a signal object and that the storage class for the object is set to ExportToFile. Because the signal is associated with a signal object, you must use the Model Explorer to confirm that the code generation configuration aligns with the ICD specification.

  3. Open the Model Explorer. In the Model Hierarchy pane, navigate to the design data in the data dictionary for the controller model (rtwdemo_fuelsys_dd_controller> External Data> rtwdemo_fuelsys_dd_controller> Design Data). In the Contents pane, select fuel_mode.

  4. In the right pane, click the Code Generation tab. Storage class must be set to ExportToFile. Confirm that properties HeaderFile, DefintionFile, and Owner match the ICD specifications global_data.h, signals.c, and rtwdemo_fuelsys_dd_controller, respectively.

Configure Code Generation for Parameters

  1. In the ICD, click the Parameters tab.

  2. In the Code Mappings editor, click the Paramters tab.

  3. Use the Filter contents box to search for parameter PressEst. The Code Mappings editor shows a row that corresponds to parameter object PressEst. Because the ICD specifies rtwdemo_fuelsys_dd_controller as the owner of PressEst, Storage Class should be set to ExportToFile.

  4. Click the icon. Check that the settings for properties HeaderFile, DefinitionFile, and Owner match the ICD specifications global_data.h, params.c, and rtwdemo_fuelsys_dd_controller, respectively. Also, make sure that a value is specified for the Identifier property.

  5. Check the Storage Class, HeaderFile, DefinitionFile, Identifier, and Owner settings for parameters PumpCon, SpeedEst, ThrotEst, and RampRateKiz.

Configure Code Generation for Numeric Types

  1. In the ICD, click the Numeric Types tab.

  2. If the Model Explorer is not open, open it.

  3. In the Model Hierarchy pane, navigate to the design data in the data dictionary for the controller model (rtwdemo_fuelsys_dd_controller> External Data> rtwdemo_fuelsys_dd_controller> Design Data).

  4. In the Contents pane, select the Simulink.NumericType object u8En7. This object represents one of the typedef statements in ex_inter_types.h.

  5. In the right pane, click the Code Generation tab. Confirm that the settings for Data scope and Header file align with the ICD specifications, Imported and ex_inter_types.h, respectively.

  6. Check and adjust the code generation configuration for numeric types s16En3, s16En7, and s16En15.

Configure Code Generation for Structures

  1. In the ICD, click the Structure Types tab.

  2. In the Model Explorer Contents pane, select EngSensors. This Simulink.Bus object represents the structure type defined in ex_inter_types.h.

  3. In the right pane, click the Code Generation tab. Confirm that the settings for Data scope and Header file align with the ICD specifications, Imported and ex_inter_types.h, respectively.

Generate and Inspect Code

1. Generate code for the controller model.

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

Build Summary

Top model targets built:

Model                          Action                       Rebuild Reason                                    
==============================================================================================================
rtwdemo_fuelsys_dd_controller  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 3m 1.371s

2. Inspect the generated code. The generated header file rtwdemo_fuelsys_dd_controller_types.h:

  • Includes (#include) the external header file ex_inter_types.h, which defines numeric data types u8En7, s16En3, and s16En7 and the structure type EngSensors

  • Defines the enumeration sld_FuelModes

file = fullfile('rtwdemo_fuelsys_dd_controller_ert_rtw',...
    'rtwdemo_fuelsys_dd_controller_types.h');
rtwdemodbtype(file,'#include "ex_inter_types.h"','} sld_FuelModes;',1,1)
#include "ex_inter_types.h"

/* Model Code Variants */
#ifndef DEFINED_TYPEDEF_FOR_sld_FuelModes_
#define DEFINED_TYPEDEF_FOR_sld_FuelModes_

typedef enum {
  LOW = 1,                             /* Default value */
  RICH,
  DISABLED
} sld_FuelModes;

The file rtwdemo_fuelsys_dd_controller_private.h includes the header file ex_inter_sigs.h. This external header file contains the extern declaration of the signal sensors, which a different software component owns.

The data header file global_data.h declares the exported parameters and signals that the ICD specifies. To share this data, other components can include this header file.

file = fullfile('rtwdemo_fuelsys_dd_controller_ert_rtw','global_data.h');
rtwdemodbtype(file,'/* Exported data declaration */',...
    'fuel_rate',1,1)
/* Exported data declaration */

/* Declaration for custom storage class: ExportToFile */
extern real32_T PressEst[855];   /* Referenced by: '<S6>/Pressure Estimation' */
extern real32_T PumpCon[551];       /* Referenced by: '<S1>/Pumping Constant' */
extern real32_T RampRateKiz[25];       /* Referenced by: '<S1>/Ramp Rate Ki' */
extern real32_T SpeedEst[1305];     /* Referenced by: '<S7>/Speed Estimation' */
extern real32_T ThrotEst[551];   /* Referenced by: '<S8>/Throttle Estimation' */
extern sld_FuelModes fuel_mode;        /* '<Root>/control_logic' */
extern real32_T fuel_rate;             /* '<Root>/fuel_rate' */

The algorithm code is in the model step function in the file rtwdemo_fuelsys_dd_controller.c. The algorithm uses the global data that the ICD identifies. For example, the algorithm uses the value of the signal fuel_mode in a switch block to control the flow of execution.

file = fullfile('rtwdemo_fuelsys_dd_controller_ert_rtw',...
    'rtwdemo_fuelsys_dd_controller.c');
rtwdemodbtype(file,'/* End of MultiPortSwitch: ''<S9>/Multiport Switch'' */',...
    '/* Outport: ''<Root>/fuel_rate'' incorporates:',0,0)
  /* SwitchCase: '<S10>/Switch Case' */
  switch (fuel_mode) {
   case LOW:
    /* Outputs for IfAction SubSystem: '<S10>/low_mode' incorporates:
     *  ActionPort: '<S12>/Action Port'
     */
    /* DiscreteFilter: '<S12>/Discrete Filter' incorporates:
     *  DiscreteIntegrator: '<S1>/Discrete Integrator'
     */
    denAccum = rtDWork.DiscreteIntegrator_DSTATE - -0.7408F *
      rtDWork.DiscreteFilter_states_g;
bdclose('rtwdemo_fuelsys_dd_controller')
Simulink.data.dictionary.closeAll('rtwdemo_fuelsys_dd_controller.sldd','-discard')

Import ICD Specifications into Simulink

You can use a MATLAB script to import data settings from the ICD into variables in the Simulink base workspace.

1. Open and inspect the example script ex_importICD_PCG.m.

edit ex_importICD_PCG

The script:

  • Imports the data from each worksheet of the ICD into variables in the base workspace.

  • Uses the imported data to configure design and code generation properties of Simulink.Signal and Simulink.Parameter objects in the base workspace.

If the base workspace already contains a data object that corresponds to a data element in the ICD, the script configures properties of the existing object. If the object does not exist, the script creates the object.

2. Load the model and run the script.

load_system('rtwdemo_fuelsys_dd_controller')
run('ex_importICD_PCG')

3. Regenerate and inspect the code.

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

Build Summary

Top model targets built:

Model                          Action                       Rebuild Reason                   
=============================================================================================
rtwdemo_fuelsys_dd_controller  Code generated and compiled  Generated code was out of date.  

1 of 1 models built (0 models already up to date)
Build duration: 0h 1m 36.732s

Considerations

  • When you make changes to an ICD, you can reuse your import script to reconfigure the model.

  • If you use a script to import data from an ICD to the base workspace, consider migrating the data objects and variables to a data dictionary. A data dictionary permanently stores and tracks changes to data objects and variables. For example, you can import the definition of enumerated type sld_FuelModes into the controller model dictionary. See Import and Export Dictionary Data and Enumerations in Data Dictionary.

  • You can store configuration settings for signal and state data elements, such as data types, minimum and maximum values, and physical units inside or outside of model files. Simulink.Signal objects store the configuration settings outside of a model file. Alternatively, you can store the configuration settings in the model file by using block and port parameters that you can access through the Model Data Editor, Property Inspector, and other dialog boxes. See Store Design Attributes of Signals and States.

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