Refactoring regarding Software Latency in a Real Time Operating System for Spaceflight

Abstract

The evolving area of reusable rockets, like the CALLISTO demonstrator, demands precision, speed, and reliability. As spacecraft systems becomes more intricate and the expectations for their performance rise, the software components ensuring their effective functioning must similarly advance. An important component in this system is the General Purpose In/Output driver in RTEMS for the LEON3 processor. This leads to the question, what specific parts of the General Purpose In/Output driver's code might be slowing things down and need a refactoring and will making changes to the GPIO interface improve how fast a LEON3 Board with RTEMS responds when using GPIO ports? To answer this research question, besides the current implementation of the General Purpose In/Output driver, two additional implementations were developed to evaluate specific aspects of General Purpose In/Output pin usage in the context of latency performance across three different test series and to compare them against each other. The central findings reveal significant performance differences between the various implementations when writing output values of a General Purpose In/Output pin. These differences can be attributed to technical factors, including the directness of access, the way data is resolved, and the testing methodology employed. Future porting of the driver into RTEMS's native interface, considering the insights from this study, can enhance the system's performance.