Embedded-Coder (C-Code)

The Matlab/Simulink Embedded-Coder generates C-Code from Simulink models. This page describes an easy way to get started with the Embedded-Coder on the UltraZohm. Use the example model uz_codegen.slx as a template for your own models. It has the recommended coding settings configured. Note the following key concepts and see the comprehensive documentation of the Embedded-Coder:

  • Every discrete-time is synchronous to the highest discrete-time in the generated model

  • independent of which sample rate is set in Simulink, each call to the step function is one discrete time step

  • Slower sample rates within the model are generated relative to the number of times the step function is called

  • Use single data type in Matlab/Simulink, which is a 32-bit float

How to use

The uz_codegen module encapsulates the code that is generated by the Embedded-Coder. This enables the usage of multiple instances of the same generated Simulink model. The API of uz_codegen has two functions:

uz_codegen_init(uz_codegen *self)

Initialization function for the codegen struct. Has to be passed a pointer to a variable of type uz_codegen.

uz_codegen_step(uz_codegen *self)

steps the model one time, i.e., all calculations inside the Simulink model are executed once. Has to be passed a pointer to a variable of type uz_codegen.

ultrazohm_sw/
└── vitis/
    ├── software/
    |   └── Baremetal/src
    |        └── Codegen/
    |            ├── uz_codegen.c
    |            ├── uz_codegen.h
    |            └── uz_codegen0_ert_rtw/
    └── SimulinkCodegen
        ├── uz_generateSimulinkModel.m
        ├── uz_setCodegenPaths.m
        └── uz_codegen.slx

Note

Code generation with Simulink creates a lot of auxiliary files when generating code (slprj folder, codeInfo.mat, ..). Please do not add them to git.

First usage

  1. Open Matlab

  2. Set your Matlab path to ultrazohm_sw/vitis/SimulinkCodegen

  3. Open uz_codegen.slx with Matlab/Simulink.

  4. The Simulink model calls uz_setCodegenPaths.m (defined as preLoadFcn callback)

  5. uz_setCodegenPaths.m sets the appropriate paths for the code generation on the UltraZohm

  6. Right-click on the subsystem uz_codegen

  7. Click C/C++ Code -> Build This System

  8. Code Generation Advisor will open

  9. Check for warnings and errors

  10. Build code for Subsystem:uz_codegen opens

  11. Click Build

  12. Code is generated and usable in Vitis

  13. Alternative: execute the script uz_generateSimulinkModel.m which executes all of the above steps

  14. Open Vitis

  15. The code is generated in ultrazohm_sw/vitis/software/Baremetal/src/Codegen/uz_codegen0_ert_rtw

  16. Code is not called by the standard Vitis project

  17. Define uz_codegen codegenInstance as a global variable in main.c of the Baremetal project

  18. Call the init function (uz_codegen_init(&codegenInstance)) inside the main

  19. Add extern uz_codegen codegenInstance to Baremtal/sw/isr.c to use the global inside the ISR

  20. Call uz_codegen_step(&codegenInstance) inside the ISR to execute the generated code

  21. codegenInstance.input holds all input values and can be set directly

  22. codegenInstance.output holds all output values and can be set directly

Define multiple instances as globals inside main.c (e.g., codegenInstance2) and call uz_codegen_init and uz_codegen_step with the respective instance to use multiple independent instances of the generated code. The input and output variables are directly accessible.

float timeFeedback;
codegenInstance.input.time=time;
uz_codegen_step(&codegenInstance);
timeFeedback=codegenInstance.output.timeFeedback;

Warning

The direct access of the variables is not recommended and not good coding practice. The approach above is simply shown to get over the first configuration barrier of the Embedded-Coder. The user is expected to fit the configuration and coding practices to their application using the information below.

Code generation settings

All Simulink configuration parameters that are not mentioned below are set to the Simulink standard settings. These settings are present if a new Simulink model from the Embedded-Coder templates is created.

Code Generation

  • System target file: ert.tlc

  • Language: C

  • Build process: Generate code only (checked)

  • Build process: Package code and artifacts (not checked)

  • Toolchain: Automatically locate an installed toolchain

Optimization

  • Remove root level I/O zero initialization unchecked to ensure everything is there and to have a way to reset

  • Remove internal data zero initialization unchecked to ensure everything is there and to have a way to reset

More Information