Designing Satelite Flight Software

When developing a CubeSat, many focus on its mechanical and electrical engineering components. This presentation details the intricacies of high-level flight software, discussing our challenges, solutions, and structure and execution of code. Our software uses FreeRTOS, a real-time operating system that functions based on tasks and priorities. The challenge lies in managing the pipeline of task execution. Priority, order, and duration must follow a deterministic path so no unexpected behaviors may occur. Memory is a scarce resource. We use statically allocated memory to reduce the possibility of memory fragmentation. Our hardware limits communication to a bitrate of 9600 bits per second. Therefore, we achieve cohesive communication through a custom-designed protocol employing checksums and identifiers that ensure robust and resilient data transfer. Our last challenge lies in internal communication with subsystems and sensors. Such subsystems include the array of AMUs (Aerospace Measurement Units) and its various supporting systems: electrical power system, transceiver, antennas, magnetorquer, and solar panels. Together with smaller sensors, the challenge lies in managing and balancing a cohesive system that maintains its health, performs the experiment, and transfers the data.