The development of satellite flight software for time-critical
applications is a challenging task. In the paper, the development of the flight
software for the Cheng Kung University Technology EXperimental satellite
(CKUTEX) microsatellite is presented. The flight software is responsible
for command validation and execution, data reception, store and downlink,
and satellite health monitoring. To meet these design requirements as well
as to accommodate potential faults, a systematic, hierarchical approach is
adopted to decompose the software system into a set of Computer Software
Configuration Items (CSCI). This greatly simplifies the coding and
maintenance of the software and, consequently, ensures the modularity,
reusability, and transparency of the software. For the space application, the
CKUTEX flight software is also designed with a fault detection and
recovery scheme. In the paper, the development approach of the flight
software, subsystem-level verification, and system tests are discussed.