GNC Flight Software

This monorepository is the home of all flight software and related on-device programs for all major GNC projects. Certain standalone and helper programs have their own repositories, see:

• Ground Station: https://github.com/Georgia-Tech-GNC/ground-station

This repository is intended to serve as a flexible and modular embedded project for designing avionics software targeting STMicroelectronics microcontrollers and FreeRTOS. More specific details can be found in the wiki.

NEW MEMBERS: Check out the setup guide and the onboarding materials in the wiki!

Git and Repository Organization Strategy

Branch Overview:

• main - Base project template and reusable drivers and code segments
• project/<project-name> - Project-specific branches for ongoing rocket projects
• other - Miscellaneous feature/development branches

It is very important that every commit in main and project-specific branches represents a functional step in project history. This makes it easy for users to go back through project commit logs and see when/how features are implemented. To help enforce this rule, project branches (and main) can only be updated using squash and merge. All features, improvements, and bugfixes should be developed on a dedicated branch, and then pulled into project branches via a PR. PR's to main and project branches should compile, pass all CI checks, and be tested on target hardware prior to being merged.

File Structure

• core/src - Source files for the active project and the shared main.c entrypoint
• core/include - Header files for the active project
• drivers/<driver-name> - Source files and headers for reusable device and peripheral drivers
• lib/<name> - Reusable submodules and utility functions
• targets/<target-name> - CubeMX-generated code, including HAL and CMSIS drivers, target-specific sources, FreeRTOS source and header files, and the target-specific main.c entrypoints

Supporting multiple targets

• Never include device-specific HAL headers (for example, stm32h7xx_hal.h). Include main.h instead, which is defined per-target and will recursively include all available HAL headers for the chosen target.
• FreeRTOS headers can be included directly, and all targets are assumed to implement it.
• All targets must call void shared_main(void) inside their main() functions immediately after initializing peripherals. The prototype for this method must go in main.h.
• Since different configurations may or may not compile with different targets, the only compilation requirement is that everything should compile when using the "dev" cmake profile (the Nucleo-h723zg target). Project branches should also compile when targeting that rocket's specific flight computer chip.

Compiling

This repository is intended to be compiled using CMake with the Ninja backend. The main CMakeLists.txt can be found in the root directory of the project. Each subdirectory (core/, drivers/, lib/, and targets/) has its own CMakeLists.txt, which is recursively included into the CMake project. Cache variables can be used to select a specific target and library list. Use ccmake to view all relevant options in a terminal user interface.

The recommended way to compile this repository is via the presets available in CMakePresets.json. The most of important of these is dev and dev-release, which builds the flight-software and all modules targeting the STM32h723zg Nucleo-144 development board.

• To configure the dev preset (you must re-run this every time the CMake configuration is modified), run the command cmake --preset dev.
• To build the dev preset, run the command cmake --build --preset dev

After running both, the compiled flight-software.elf file should appear in build/dev. This project also supports Doxygen as an optional dependency. If you have it installed, then compiling will automatically generate documentation for the project. This documentation can be viewed by opening build/dev/html/index.html in a browser window.