Deterministic SpaceWire networks

TL;DR: This research contributes a novel SpaceWire-D scheduling strategy using a combination of path selection and transaction allocation algorithms that allows for a Space Wire-D network to be defined as a list of periodic, aperiodic and payload data bandwidth requirements and outputs aList of paths and an allocation of transactions to time-slots which satisfy the networking requirements of a mission.

Abstract: SpaceWire-D is an extension to the SpaceWire protocol that adds deterministic capabilities over existing equipment. It does this by using time-division multiplexing, controlled by the sequential broadcasting of time-codes by a network manager. A virtual bus abstraction is then used to divide the network architecture into segments in which all traffic is controlled by a single Remote Memory Access Protocol (RMAP) transaction initiator. Virtual buses are then allocated a number of time-slots in which they are allowed to operate, forming the SpaceWire-D schedule. This research starts by contributing an efficient embedded SpaceWire-D software layer, running on top of the RTEMS real-time operating system, for use in the initiators of a SpaceWire-D network. Next, the SpaceWire-D software layer was used in two LEON2-FT processor boards in combination with multiple other RMAP target boards, routers, a network manager, and a host PC running a suite of applications to create a SpaceWire-D Demonstrator. The SpaceWire-D software layer and SpaceWire-D Demonstrator were used to verify and demonstrate the SpaceWire-D protocol during the ESA SpaceWire-D project and resulted in multiple deliverables to ESA. Finally, this research contributes a novel SpaceWire-D scheduling strategy using a combination of path selection and transaction allocation algorithms. This strategy allows for a SpaceWire-D network to be defined as a list of periodic, aperiodic and payload data bandwidth requirements and outputs a list of paths and an allocation of transactions to time-slots which satisfy the networking requirements of a mission.