Generated C code inspection in Simulink

Introduction

Generated C code inspection helps you check the code created automatically from Simulink models. It ensures the code works as expected and is easy to understand.

You want to verify that the automatic code matches your Simulink model logic.

You need to find errors or inefficiencies in the generated C code.

You want to learn how Simulink converts models into C code for embedded systems.

You need to document or explain the generated code to your team.

You want to optimize or customize the generated code for better performance.

Syntax

Simulink

1. Open your Simulink model.
2. Configure code generation settings.
3. Generate C code using Simulink Coder.
4. Use the Code Inspector tool to review the generated code.
5. Navigate through code files and compare with model elements.

The Code Inspector is a graphical tool inside Simulink for easy code review.

You can link code sections back to model blocks for better understanding.

Examples

This command generates C code from the Simulink model named 'my_model'.

Simulink

simulink_model = 'my_model';
rtwbuild(simulink_model);

This sequence opens the model, sets it to generate code only (no build), then generates the code.

Simulink

open_system('my_model');
set_param('my_model', 'GenerateCodeOnly', 'on');
rtwbuild('my_model');

This command opens the Code Inspector for the generated code folder 'my_model_ert_rtw'.

Simulink

codeInspector('my_model_ert_rtw');

Sample Program

This example opens a Simulink model called 'simple_model', sets it to generate embedded C code only, builds the code, then opens the Code Inspector to review the generated files.

Simulink

model = 'simple_model';
open_system(model);
set_param(model, 'SystemTargetFile', 'ert.tlc');
set_param(model, 'GenerateCodeOnly', 'on');
rtwbuild(model);
codeFolder = [pwd filesep model '_ert_rtw'];
codeInspector(codeFolder);

Important Notes

Always check that your model is error-free before generating code.

Use the Code Inspector to trace code back to model blocks for easier debugging.

Generated code may be complex; focus on key functions and variables related to your model.

Summary

Generated C code inspection helps verify and understand code from Simulink models.

Use Simulink Coder and Code Inspector tools to generate and review code.

Inspecting code ensures correctness and helps optimize embedded system software.

Practice

1. What is the main purpose of inspecting generated C code from a Simulink model?

easy

A. To run the Simulink model faster in simulation

B. To create new Simulink blocks automatically

C. To verify the correctness and understand the behavior of the generated code

D. To convert C code back into Simulink diagrams

Solution

1. Step 1: Understand the role of generated code inspection

   Generated C code inspection is used to check if the code matches the Simulink model's logic and to understand how the model is translated into code.

2. Step 2: Eliminate unrelated options

   Creating new blocks, speeding simulation, or converting code back to diagrams are not purposes of code inspection.

3. Final Answer:

   To verify the correctness and understand the behavior of the generated code -> Option C

4. Quick Check:

   Code inspection = verify and understand code [OK]

Hint: Code inspection checks correctness and logic match [OK]

Common Mistakes:

• Thinking code inspection creates new blocks
• Confusing code inspection with simulation speedup
• Assuming code inspection converts code back to diagrams

2. Which Simulink tool is primarily used to generate C code from a model?

easy

A. Simulink Profiler

B. Simulink Data Inspector

C. Simulink Real-Time

D. Simulink Coder

Solution

1. Step 1: Identify the tool for code generation

   Simulink Coder is the tool designed to generate C and C++ code from Simulink models.

2. Step 2: Confirm other tools' purposes

   Profiler measures performance, Data Inspector visualizes signals, Real-Time runs models on hardware, none generate code.

3. Final Answer:

   Simulink Coder -> Option D

4. Quick Check:

   Code generation tool = Simulink Coder [OK]

Hint: Simulink Coder generates C code from models [OK]

Common Mistakes:

• Confusing Profiler with code generator
• Mixing Data Inspector with code generation
• Assuming Real-Time generates code

3. Given the following snippet from generated C code, what does the variable rtU.inputSignal represent?

/* Model step function */
void model_step(void) {
  real_T output = rtU.inputSignal * 2.0;
  rtY.outputSignal = output;
}

medium

A. An output signal from the model

B. An input signal to the model

C. A local temporary variable

D. A constant value defined in the code

Solution

1. Step 1: Analyze variable naming conventions

   In generated code, rtU prefix usually denotes inputs to the model, so rtU.inputSignal is an input.

2. Step 2: Check usage in code

   The code multiplies rtU.inputSignal by 2 and assigns to output, confirming it is an input value.

3. Final Answer:

   An input signal to the model -> Option B

4. Quick Check:

   rtU = inputs, rtY = outputs [OK]

Hint: rtU prefix means input signals in generated code [OK]

Common Mistakes:

• Thinking rtU is output or local variable
• Assuming inputSignal is a constant
• Confusing variable scope

4. You find this line in generated C code:

int32_T counter = 0
counter += 1;

What is the error here?

medium

A. Missing semicolon after the first statement

B. Incorrect variable type for counter

C. counter cannot be incremented like this

D. Variable counter should be declared as float

Solution

1. Step 1: Check syntax of variable declaration

   The first line declares counter but misses a semicolon at the end, which is required in C.

2. Step 2: Validate increment statement

   The increment counter += 1; is correct syntax and valid for int32_T type.

3. Final Answer:

   Missing semicolon after the first statement -> Option A

4. Quick Check:

   Every C statement ends with ; [OK]

Hint: Check for missing semicolons in C code lines [OK]

Common Mistakes:

• Ignoring missing semicolon errors
• Thinking increment syntax is wrong
• Confusing variable types unnecessarily

5. You want to optimize generated C code by removing unused signals. Which step should you take in Simulink before generating code?

hard

A. Use the Code Mappings editor to mark unused signals as 'Exclude from code'

B. Enable signal logging for all signals

C. Increase the sample time of all blocks

D. Disable the Simulink Coder entirely

Solution

1. Step 1: Understand code optimization options

   Simulink allows marking signals as unused in the Code Mappings editor to exclude them from generated code.

2. Step 2: Evaluate other options

   Enabling logging increases code size, increasing sample time changes model behavior, disabling coder stops code generation.

3. Final Answer:

   Use the Code Mappings editor to mark unused signals as 'Exclude from code' -> Option A

4. Quick Check:

   Exclude unused signals via Code Mappings [OK]

Hint: Mark unused signals to exclude in Code Mappings editor [OK]

Common Mistakes:

• Enabling logging increases code size
• Changing sample time affects model timing
• Disabling coder stops code generation