Celestial is an open-source flight controller designed for autonomous drone projects. Compared to other flight controllers, it's built from the ground up to address several issues:

• Cross-platform compatibility.
• Ease of programming and testing.
• Safety-critical code.

Celestial is currently in early developement and does not yet boast many features. Currently, it can be run similar to other flight controllers. (** = in development, likely not commited yet)

• Acro and self-stablizing flight modes.
• ** Automatic takeoff and landing.
• ** Altitude hold, using ultrasonics and barometer.
• ** Acoustic localization for position estimation.
• ** GPS waypoint navigation.

Celestial is written as a basic C library that can be compiled to any device that can compile C99. Devices can include STM32F4, XMOS, Arduino, Raspberry Pi, and others. In order to use processor specific functionality (ie. I2C, SPI), a hardware abstraction layer needs to be written to interface between Celestial and the hardware.

Currently, the following devices are planned to be supported:

• XMOS (https://github.com/CelestialFlight/Celestial_XMOS.git)
• STM32F4 (coming soon)
• Raspi (coming soon)
• Arduino (coming soon)

Celestial was written with safety in mind from it's conception. This code follows what is called the "Power of Ten" and goes over several rules. In short, they are:

• No goto, setjmp/longjmp or indirect recursion
• All loops should have an upper bound.
• No dynamic memory allocation after initialization.
• Functions should be kept short (less then N lines).
• Assertions should average 2 per function.
• Declare objects at smallest possible scope.
• The return value of non-void functions should always be checked.
• Limit the preprocessor to header files and simple macros.
• • The use of pointers should be restricted.
• All code must be compiled with all compiler warnings on.

All code in should also be unit-tested and built before pushing.