Middleware Technique to Synchronize Applications Across Modules Using an ARINC 653 RTOS
Roscoe C. Ferguson · 2007
[Abstract] During the past several years, safety critical systems have been incorporating the Aeronautical Radio, Inc. (ARINC) 653 specification into their implementation. ARINC 653 specifies the baseline-operating environment for application software used within Integrated Modular Avionics (IMA). NASA’s Constellation Program will consist of systems of systems each requiring the need for safety critical avionics. These systems normally have the requirement to be two-fault tolerant and are composed of multiple computers that either operate in parallel and vote or operate as master and backup. For either case, some form of computer synchronization is required. The Space Shuttle Program avionics use computers that operate in parallel and vote to achieve two-fault tolerance. This is accomplished primarily using an architecture that relies on software-based synchronization and has been successful over the service life of the Shuttle Program. The Shuttle approach for synchronization can be incorporated into ARINC 653 systems using the concept of partition synchronization. In this concept, the applications executing on each of the primary computers are synchronized at partition context switches. COTS RTOS products such as VxWorks and Integrity provide hooks that can be used to support this concept. These hooks are integrated with the ARINC 653 Partition Scheduler to support operations at the start of both Major and Minor Frames.