C to C++: Using Abstract Interfaces to Create Hardware Abstraction Layers (HAL)
In C to C++, we've been exploring how to transition from a C developer to a C++ developer when working in embedded system. In this post, we will explore how to leverage classes to create hardware abstraction layers (HAL). You'll learn about the various inheritance mechanisms, what an virtual function is, and how to create an abstract class.
Summary
This blog post shows how an embedded C developer can start using C++ to build hardware abstraction layers (HALs) for microcontrollers. It explains object-oriented tools—classes, inheritance, virtual functions, and abstract classes—and demonstrates how to design clean, portable HAL interfaces that improve testability and reuse.
Key Takeaways
- Design abstract HAL interfaces using pure virtual (abstract) C++ classes to decouple hardware from application code.
- Choose appropriate inheritance and composition patterns to implement concrete drivers for different MCUs and peripherals.
- Manage virtual function overhead and optimize for embedded constraints (inlining, final, LTO, and vtable considerations).
- Migrate existing C drivers to C++ progressively and integrate C code with C++ interfaces safely.
- Use interface-based design to enable unit testing and mocking of hardware-dependent code.
Who Should Read This
Embedded firmware engineers experienced in C who want practical guidance on adopting C++ to create modular, portable, and testable HALs for microcontrollers.
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