Скачать или смотреть Implementing Bare Metal Code on STM32F103C8 Using GCC

Discover how to write bare metal code for the STM32F103C8 microcontroller using assembly and GCC, including tips for linker scripts and vector table initialization.
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Writing Bare Metal Code on STM32F103C8 Using GCC

Have you ever found yourself stuck while trying to write bare metal code in assembly for the STM32F103C8 microcontroller? You’re not alone. Many developers face challenges getting their code to compile and run due to various issues like linker script errors and vector table misconfigurations. In this guide, we will take a deep dive into the proper way to set up your bare metal code environment using the GCC toolchain. We'll address common problems and provide organized steps for troubleshooting.

Understanding the Bare Metal Environment

Bare metal programming refers to writing low-level code that interacts directly with the hardware without an operating system. This allows for precise control over hardware, but it comes with its own set of complexities. Here’s a general approach to writing your code:

Initialize the Stack Pointer: When the microcontroller resets, it must check the vector table and execute the reset handler. The stack pointer must be set up correctly to prevent crashes.

Execute Main Code: After the initialization, the program should jump to the main function, where the application logic resides.

Linker Script Configuration

One of the primary sources of errors in bare metal coding is the linker script. The linker script defines memory areas and how sections of your code are laid out in flash and RAM. Below are tips to set up a linker script correctly:

Basic Linker Script

A simplified linker script looks like this:

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This should define a section in flash memory for your program instructions. Ensure that you adjust the ORIGIN and LENGTH parameters according to your microcontroller's specifications.

Correcting Linker Script Errors

Ensure that the vector table is positioned in memory correctly. To place the vector table at the start of the executable section, the ENTRY() directive can be adjusted.

Optimize the complexity; often, a simpler script can resolve many issues. Avoid unnecessary complexity unless needed.

Vector Table and Handler Execution

To make sure the vector table is correctly set up, you can organize your ASM code as follows:

[[See Video to Reveal this Text or Code Snippet]]

Key Points About the Vector Table:

The stack address must be correctly defined as a function.

Use the .thumb_func directive to ensure the microcontroller correctly interprets the function type.

Compiling and Linking Your Code

The compilation process involves assembling, linking, generating object files, and dumping the output. Here are the compilation commands:

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This command setup will yield a binary output that you can use to flash your STM32F103C8.

Debugging Disassembly

Always analyze your disassembly after building. This helps ensure the correct instruction layout. Here’s a command to view the disassembly:

[[See Video to Reveal this Text or Code Snippet]]

Check that your reset handler directly points to your main function and that code alignment is respected.

Conclusion

Writing bare metal code for the STM32F103C8 using the GCC toolchain can be straightforward if you understand the basics of stack initialization, linker scripts, and vector tables. By keeping your linker scripts simple and ensuring proper addressing in your code, you can avoid many common pitfalls.

You are now equipped with the knowledge to tackle the typical issues you might face when developing bare metal applications. With practice and patience, you will become adept at handling the intricacies of microcontroller programming.

Happy coding!