STM32 Embedded C++ Project 🚀

Overview 🌐

This repository demonstrates the application of C++ in embedded systems, specifically using STM32 microcontrollers. The goal is to provide a learning resource for developers transitioning from general C++ programming to embedded development. The project includes core components, hardware drivers, and practical examples, all aimed at showcasing the capabilities of STM32 microcontrollers and the efficiency of C++ in embedded programming.

Recent changes (Sept 17, 2025)

This project received a focused refactor of the GPIO/EXTI subsystem and an example application demonstrating interrupt-driven button handling.

• Implemented a static registry for EXTI-capable GPIO objects so external interrupts dispatch to the correct C++ object and callback.
• Moved the EXTI IRQ handlers into the CubeMX-friendly Core/Src/stm32l4xx_it.c (C ISRs) which forward to a C-wrapper that calls GPIO::GPIOEXTI::handleInterrupt(pin).
• Removed the separate gpio_isr_example.cpp file and added an App example (App/Src/App.cpp) that uses LED on PB11 and buttons on PC0..PC3.
• Refactored GPIOEXTI::configureEXTI() to simplify EXTI source selection and SYSCFG mapping.
• Switched to RAII-style initialization: constructors perform hardware configuration and GPIOEXTI objects register/unregister themselves in the static registry; a destructor cleans up on deletion.
• Improved const-correctness and API cleanup (removed virtual init() from the base class; updated headers).

If you use the GPIO/EXTI features, ensure the LL driver headers are available and your CubeMX configuration enables the EXTI/SYSCFG peripheral clocks.

Example: what was added in App/Src/App.cpp

• LED on PB11 (push-pull output).
• Buttons on PC0..PC3 configured with internal pull-ups and falling-edge triggers.
• Button behaviors:
  • PC0: toggle LED
  • PC1: LED ON
  • PC2: LED OFF
  • PC3: cycle LED patterns (OFF → ON → slow blink → fast blink)

The application registers lightweight callbacks for each button and defers heavier work to the main loop.

ISR wiring and notes

• The C IRQ handlers (in Core/Src/stm32l4xx_it.c) now check EXTI pending flags and call a small C bridge function GPIO_EXTI_HandleInterrupt(pin) which forwards into C++.
• For grouped IRQs (EXTI5..9 and EXTI10..15) the ISR scans all pending lines and calls the bridge for each active pin.
• Callback functions execute in interrupt context — keep them short and non-blocking. Use flags/atomic variables or an RTOS queue to pass work to the main task.

Quick usage snippet

// Create LED on PB11 and buttons on PC0..PC3
auto led = new GPIO::GPIOOutput(GPIOB, 11, GPIO::PinOutputType::PUSH_PULL);
auto b0 = new GPIO::GPIOEXTI(GPIOC, 0, GPIO::EXTITrigger::FALLING, GPIO::PinPull::PULL_UP);
// set callbacks and enable
b0->setCallback([](){ /* quick action */ });
b0->enableInterrupt();

Build & run notes

• Open in STM32CubeIDE and build as usual.
• Ensure stm32l4xx_ll_* headers are available and CubeMX config enables the required peripherals (GPIO, SYSCFG, NVIC lines for EXTI).

Recommendations

• Verify NVIC group handling on your STM32 part: EXTI lines share IRQs — disabling a shared NVIC line affects all pins on the same group.
• Use the App example as a starting point and adapt pin numbers / ports to your board.

Repository Structure 🗂️

• Core/: Core components and configurations.
• App/: Example applications demonstrating usage.
• Inc/: Header files for classes and interfaces.
• Src/: Source files for implementations.
• Drivers/: Hardware drivers and related files.

Features ✨

• GPIO Class: Comprehensive implementation for STM32 microcontrollers.
• Modern C++: Utilizes C++11/14/17 features.
• HAL Integration: Seamless hardware control via STM32 HAL.

Getting Started 🚀

Prerequisites 📋

• STM32CubeIDE or a compatible IDE.
• Basic C++ and embedded systems knowledge.
• STM32 development board (e.g., STM32F4 Discovery, STM32 Nucleo).

Installation 💻

1. Clone the repository:

   git clone https://github.com/MootSeeker/STM32_Embedded_CPP.git
   cd STM32_Embedded_CPP

2. Open in STM32CubeIDE.
3. Build and upload to your STM32 board.

ToDo ✅

• Complete GPIO class
• Implement class for Timer
• Implement class for ADC
• Implement class for DAC
• Implement class for CRC
• Implement class for SPI
• Implement class for I2C
• Implement class for CAN
• Implement class for QSPI
• Implement class for USART
• Create examples for all interfaces
• Transition to Bare Metal, removing HAL dependencies

Statistics 📊

Languages Used in This Repository

Contributing 🤝

Contributions are welcome! Please fork the repository, create a feature branch, commit your changes, and open a pull request.

License 📜

This project is licensed under the MIT License. See the LICENSE file for details.

Contact 📧

For questions or feedback, please open an issue on the repository or contact MootSeeker.

Happy coding!