Steve Parkes1 and Philippe Armbruster2
1University of Dundee
2European Space Agency, ESTEC
SpaceWire has emerged as one of the main data-handling networks for spacecraft since the SpaceWire standard was published in January 2003 . It is now being used on many ESA, NASA and JAXA spacecraft and by other space agencies, research organisations and space industry across the world. SpaceWire is designed to connect together high data-rate sensors, processing units, memory sub-systems and the down link telemetry sub-system. It provides high-speed (2 Mbits/s to 200 Mbits/s), bi-directional, full-duplex, data links which connect together the SpaceWire enabled equipment. Networks can be built to suit particular applications using point-to-point data links and routing switches. Application information is sent along a SpaceWire link in discrete packets. Control and time information can also be sent along SpaceWire links. One of the main advantages of SpaceWire is its low complexity (low gate count) and the fact that it can be implemented easily in both ASICs and FPGAs. SpaceWire is supported by several radiation tolerant ASICs designed by or for ESA, NASA and JAXA. Extensive test and development equipment is available .
This paper starts with a brief overview of SpaceWire and then considers how SpaceWire may be used to implement a variety of different architectures. First the use of point to point links is considered, the simplest and most widely used form of SpaceWire network. The ways in which the reliability of point to point links can be made fault tolerant using redundant links are then described. The use of routing switches to build more complex networks is then considered building the analysis step by step and examining the advantages, disadvantages and potential uses of each type of network. An example of one of the more complex networks is illustrated below:
 S.M. Parkes et al, ECSS-E-50-12A, “SpaceWire, Links, Nodes, Routers and Networks", Issue 1, European Cooperation for Space Data Standardization, January 2003.
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