SpaceWire

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SpaceWire Specifications
Created by European Space Agency
Speed 2.0–400 Mbit/s
Style Serial
Hotplugging interface Yes
External interface Yes
SpaceWire Connector Specifications
Type Data connector
Designer European Space Agency
Hot pluggable Yes
External Yes
Audio signal No
Video signal No
Pins 9
Connector Micro-D
Data signal Yes
Bitrate 2.0–400 Mbit/s
Protocol Serial
Pin Name Description
Pin 1 DIN+ Data In Pos.
Pin 2 SIN+ Strobe In Pos.
Pin 3 Inner Shield Ground
Pin 4 SOUT- Strobe Out Neg.
Pin 5 DOUT- Data Out Neg.
Pin 6 DIN- Data In Neg.
Pin 7 SIN- Strobe In Neg.
Pin 8 SOUT+ Strobe Out Pos.
Pin 9 DOUT+ Data Out Pos.

SpaceWire is a spacecraft communication network based in part on the IEEE 1355 standard of communications. It is coordinated by the European Space Agency (ESA) in collaboration with international space agencies including NASA, JAXA and RKA. Within a SpaceWire network the nodes are connected through low-cost, low-latency, full-duplex, point-to-point serial links and packet switching wormhole routing routers. SpaceWire covers two (physical and data-link) of the seven layers of the OSI model for communications.

Architecture[edit]

SpaceWire's modulation and data formats generally follow the data strobe encoding - differential ended signaling (DS-DE) part of the IEEE Std 1355-1995. SpaceWire utilizes asynchronous communication and allows speeds between 2 Mbit/s and 400 Mbit/s. DS-DE is well-favored because it describes modulation, bit formats, routing, flow control and error detection in hardware, with little need for software. SpaceWire also has very low error rates, deterministic system behavior, and relatively simple digital electronics. SpaceWire replaced old PECL differential drivers in the physical layer of IEEE 1355 DS-DE by low-voltage differential signaling (LVDS). SpaceWire also proposes the use of space-qualified 9-pin connectors. SpaceWire and IEEE 1355 DS-DE allows for a wider set of speeds for data transmission, and some new features for automatic failover. The fail-over features let data find alternate routes, so a spacecraft can have multiple data buses, and be made fault-tolerant. SpaceWire also allows the propagation of time interrupts over SpaceWire links, eliminating the need for separate time discretes.

Uses[edit]

SpaceWire is used worldwide. Its use began primarily in ESA projects, but it is currently used by NASA, JAXA, RKA, and many other organizations and companies. Some NASA projects using it include the James Webb Space Telescope, Swift's Burst Alert Telescope, the Lunar Reconnaissance Orbiter, LCROSS, the Geostationary Operational Environmental Satellite (GOES-R), and the SCaN Testbed, previously know as the Communications, Navigation, and Networking Reconfigurable Testbed (CoNNeCT). It has also been selected by the United States Department of Defense for Operationally Responsive Space. SpaceWire initiatives are being coordinated between several Space Agencies in the frame of CCSDS in order to extend its communication model to the Network and Transport Layers of the OSI model.

Protocols[edit]

The ESA has a draft specification in place for the Protocol ID.

The following Protocol ID's have been assigned in ECSS-E-ST-50-11:

  • 1: Remote Memory Access Protocol (RMAP)
  • 2: CCSDS Packet Transfer Protocol
  • 238: Proposal for Reliable Data Delivery Protocol (RDDP) (used on GOES-R)
  • 239: Serial Transfer Universal Protocol (STUP) (Used on SMCS-332 ASIC)

References[edit]

External links[edit]

Commercial providers of SpaceWire equipment:

SpaceWire IP Cores:

Articles: