SpaceWire-D on the castor spaceflight processor

SpaceWire-D is a deterministic extension to the SpaceWire protocol designed to satisfy hard real-time constraints on a SpaceWire network. This allows a single SpaceWire network to be used for both control applications and payload data-handling. The Atmel AT6981 Castor device is a LEON2-FT based system-on-chip with multiple integrated peripherals including an eight-port SpaceWire router and three internal SpaceWire engines each containing three DMA channels, an RMAP initiator, and an RMAP target. This paper describes the SpaceWire-D protocol; the design of RTEMS networking software to test the protocol using the AT6981 system-on-chip; and the results of those tests.