The implementation of a COTS based fault tolerant avionics bus architecture

X2000 is a technology program at the Jet Propulsion Laboratory to develop enabling technologies for future flight missions at affordable cost. The cost constraints mandate the use of commercial-off-the-shelf (COTS) components and standards in the X2000 multi-mission avionics system architecture. The X2000 has selected two commercial bus standards, the IEEE 1394 and I²C, as the avionics system buses. These two buses work together to provide the performance, scalability, low power consumption, and fault tolerance required by long life deep space missions. We report our approach to implementing a fault-tolerant bus architecture for the X2000 avionics system using these two COTS buses. The system approach is described first. Then, the focus of the rest of the discussion is on the implementation of two ASICs, digital I/O and mixed signal I/O ASICs, which are the key components of this COTS based fault-tolerant bus architecture