1. SpaceWire Architectures Steve Parkes Space Technology Centre, University of Dundee, Scotland, UK

2. ParkesMAPLD2006 2222 Point to point link Instrument Memory Or Processor SpaceWire

3. ParkesMAPLD2006 2223 Point to point link  Advantages  Simple interface  Low power per Mbit/s  No problem with router blocking  Full bandwidth of link available to application  Disadvantages  No redundancy  May be inefficient if link bandwidth not fully utilised  But can use auto-start, disable on silence  Applications  Direct connection of instrument to memory or processor

4. ParkesMAPLD2006 2224 Redundant point to point links Instrument Memory Or Processor SpaceWire Prime Redundant  Redundancy of SpaceWire links only  Could do this with one SpaceWire interface  And a 2x2 LVDS switch or two LVDS drivers/receivers  Alternatively two SpaceWire interfaces at each end  To provide redundancy of the interfaces

5. ParkesMAPLD2006 2225 Redundancy at physical level SpaceWire Interface 2x2 LVDS CrossPoint LVDS Driver Receiver LVDS SpaceWire Interface LVDS Driver Receiver LVDS CMOS

6. ParkesMAPLD2006 2226 Redundant point to point links Instrument Prime Memory / Processor Prime SpaceWire Prime Redundant Instrument Redundant Memory / Processor Redundant

7. ParkesMAPLD2006 2227 Redundant point to point links  Advantages  As single point to point link  Redundancy  Simple architecture  Disadvantages  Mass penalty as several links needed for redundancy  Inefficient if bandwidth not fully utilised  Applications  Direct connection of instrument to memory or process  Redundancy used where single point failure not acceptable

8. ParkesMAPLD2006 2228 Router Instrument 1 Memory Instrument 2 Processor Router

9. ParkesMAPLD2006 2229 Router  Advantages  Versatile architecture  All units can talk to one another through router  Control and data can be sent over network  Control flow generally opposite direction to data flow  Disadvantages  Have to be aware of potential blocking in router  Need to consider traffic on network  Router is single point failure  Applications  Payload data-handling systems  With more than one instrument  Or multiple possible destinations for data  Instrument to memory to processor to memory

10. ParkesMAPLD2006 22210 Router with redundant links Instrument 1 Memory Instrument 2 Processor Router

11. ParkesMAPLD2006 22211 Router with redundant links  Advantages  Redundancy of SpaceWire links  Router can auto-start and disable on silence  To support rapid switching to redundant links  Group Adaptive Routing  To support higher bandwidths  Disadvantages  Router is single point failure  Applications  None

12. ParkesMAPLD2006 22212 Redundant routers Instrument 1 Memory Instrument 2 Processor Router

13. ParkesMAPLD2006 22213 Redundant routers  Advantages  No single point failures  Disadvantages  Routers not really giving any advantage  Over system without routers  Mass penalty with number of links  Power penalty with routers  Applications  None

14. ParkesMAPLD2006 22214 Prime Redundant Routers in data-handling unit Instrument Prime Memory Instrument Redundant Processor Router Memory Processor

15. ParkesMAPLD2006 22215 Routers in data-handling unit  Advantages  Supports multiplexing of several instruments  Support prime/redundant instruments  No single point failures  Lower mass penalty of links  Since several links embedded in data-handling units  Disadvantages  None  Applications  Payload data-handling systems  With redundancy

16. ParkesMAPLD2006 22216 Prime Redundant Multiple Instruments to data-handling unit Instrument 1 Memory Instrument 2 Processor Router Memory Processor Instrument 3

17. ParkesMAPLD2006 22217 Multiple Instruments to data-handling unit  Advantages  Supports multiplexing of several instruments  Support prime/redundant data-handling units  No single point failures (except instruments)  Lower mass penalty of links  Since several links embedded in data-handling units  Disadvantages  None  Applications  Payload data-handling systems  For multiple instruments

18. ParkesMAPLD2006 22218 Prime Redundant Routers in instruments Instrument 1 Memory Instrument 2 Processor Router Memory Processor Instrument 3 Router

19. ParkesMAPLD2006 22219 Routers in instruments  Advantages  None  Disadvantages  Routers do not give any redundancy benefits  Added power of routers  Applications  None

20. ParkesMAPLD2006 22220 Prime Redundant Instruments concentrator Instrument 1 High Rate Memory Instrument 2 Processor Router Memory Processor Instrument 3 Router Instrument 4 Instrument 5

21. ParkesMAPLD2006 22221 Instrument concentrator  Advantages  Reduced cable mass  High rate instrument(s)  Direct connection to data-handling unit  Low to moderate rate instruments  Connected via concentrating router  Disadvantages  Concentrating Router is not redundant  Applications  Payload data-handling systems  With distributed clusters of instruments  Being served by centralised data-handling unit

22. ParkesMAPLD2006 22222 Prime Redundant Instruments concentrator redundant Instrument 1 High Rate Memory Instrument 2 Processor Router Memory Processor Instrument 3 Router Instrument 4 Instrument 5 Router

23. ParkesMAPLD2006 22223 Instrument concentrator redundant  Advantages  Reduced cable mass  High rate instrument(s)  Direct connection to data-handling unit  Low to moderate rate instruments  Connected via concentrating routers  Concentrating routers are redundant  Both concentrating routers could be active  Provide graceful degradation  Disadvantages  Concentrated instruments in same unit or large number of links  Applications  Payload data-handling systems  With distributed clusters of instruments  Being served by centralised data-handling unit

24. ParkesMAPLD2006 22224 Prime Redundant Group adaptive routing Instrument 1 High Rate Memory Instrument 2 Processor Router Memory Processor Instrument 3 Router Instrument 4 Instrument 5 Router GAR

25. ParkesMAPLD2006 22225 Group Adaptive Routing  Advantages  Increased bandwidth to memory and/or processor  Provides instant graceful degradation in case of a link failure  Disadvantages  Extra cable mass  Unless inside a unit  Applications  High data rate payload data-handling systems

26. ParkesMAPLD2006 22226 Prime Redundant Bridge to low data rate bus Instrument 1 High Rate Memory Instrument 2 Processor Router Memory Processor Instrument 3 Router Instrument 4 Sensor A RTC Sensor B Sensor C

27. ParkesMAPLD2006 22227 Bridging  Advantages  Multiple low data rate sensors attached to low speed bus  Sensor data packed and sent to data-handling unit over SpaceWire  Legacy devices supported  E.g. Mil-Std 1553  Disadvantages  Two types of bus/network used  Applications  Data handling systems  Legacy device support

28. ParkesMAPLD2006 22228 Integrated architecture Prime Redundant Instrument 1 High Rate Memory Instrument 2 Processor Router Memory Processor Instrument 3 Router Instrument 4 Sensor A RTC Sensor B Sensor C Telemetry / Telecommand Prime Telemetry / Telecommand Redundant

29. ParkesMAPLD2006 22229 Summary  SpaceWire can support a wide range of data- handling system architectures  Point to point links  Redundant point to point links  Networks  Redundant networks