Real-Time Responsiveness and Communication Validation Platform for CubeSats

This article presents a real-time testing platform designed to evaluate the timing behavior and communication reliability of CubeSat subsystems. At its core, the platform integrates a custom logger, along with mock software modules that simulate key CubeSat subsystems. These modules are implemented using the Zephyr real-time operating system (OS) and communicate using the CubeSat space protocol (CSP) over a controller area network bus. The system supports controlled and repeatable experimentation, enabling precise assessment of message latency, deadline adherence, and intertask communication dynamics. In addition, the platform offers extensible interfaces to support the integration and testing of flight software components under realistic operational constraints. The proposed platform facilitates early stage design validation and performance characterization within the CubeSat development lifecycle, offering deeper insights into intersubsystem communication behavior. This enables development teams to deliver more reliable software and produce more accurate data link budgets, with particular emphasis on timing determinism and subsystem interaction fidelity.