 | This article includes a list ofgeneral references, butit lacks sufficient correspondinginline citations. Please help toimprove this article byintroducing more precise citations.(August 2011) (Learn how and when to remove this message) |
| Created by | European Space Agency |
|---|---|
| Speed | 2.0–400 Mbit/s |
| Style | Serial |
| Hotplugging interface | Yes |
| External interface | Yes |
| Website | spacewire.esa.int |
| Type | Data connector | ||
|---|---|---|---|
| Production history | |||
| Designer | European Space Agency | ||
| General specifications | |||
| Hot pluggable | Yes | ||
| External | Yes | ||
| Audio signal | No | ||
| Video signal | No | ||
| Pins | 9 | ||
| Connector | Micro-D | ||
| Data | |||
| Data signal | Yes | ||
| Bitrate | 2.0–400 Mbit/s | ||
| Protocol | Serial | ||
| Pinout | |||
| 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 aspacecraftcommunication network based in part on theIEEE 1355 standard of communications. It is coordinated by theEuropean Space Agency (ESA) in collaboration with international space agencies includingNASA,JAXA, andRKA.
Within a SpaceWire network the nodes are connected through low-cost, low-latency,full-duplex,point-to-point serial links, andpacket switchingwormhole routing routers.
SpaceWire's modulation and data formats generally follow thedata strobe encoding -differential ended signaling (DS-DE) part of the IEEE Std 1355-1995. SpaceWire utilizesasynchronous communication and allows speeds between 2 Mbit/s and 200 Mbit/s, with initial signalling rate of 10 Mbit/s.[1] DS-DE is well-favored because it describes modulation, bit formats, routing,flow control, anderror 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 oldPECL differential drivers in the physical layer of IEEE 1355 DS-DE bylow-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 automaticfailover. The fail-over features let data find alternate routes, so a spacecraft can have multiple data buses, and be madefault-tolerant. SpaceWire also allows the propagation of time interrupts over SpaceWire links, eliminating the need for separate time discretes.
Each transferred character starts with a parity bit and a data-control flag bit. If data-control flag is a 0-bit, an 8-bit LSB character follows. Otherwise one of the control codes, including end of packet (EOP).[2]
The network data frames look as follows:
| Address byte | Address byte... | Protocol ID | Frame data |
One or more address bytes are used for the routing. Addresses are either physical ones (0–31), or logical ones. The difference is that the physical addresses are deleted from the frame header during routing - which is used for hop-based routing (based on path specified in the frame itself). Logical addresses may be deleted as well, depending on the router configuration.
The hardware devices may be connected either directly, or via a SpaceWire router. In the former case, usually pairs of devices are used to guarantee a fail-safe operation, which is handled by the software.
A SpaceWire router is usually acrossbar switch-type device, operating inwormhole switching mode. This also may limit the speed of the communication to the lowest common speed.[3] The routing decisions are based on the programmed routing table and the initial incoming frame contents.
SpaceWire is used all around the globe.[4]Its use began primarily inESA projects, but it is currently used byNASA,JAXA,RKA, and many other organizations and companies. Some NASA projects using it include theJames Webb Space Telescope,Swift'sBurst Alert Telescope, theLunar Reconnaissance Orbiter,LCROSS, theGeostationary Operational Environmental Satellite (GOES-R), and the SCaN Testbed, previously known as the Communications, Navigation, and Networking Reconfigurable Testbed (CoNNeCT). It has also been selected by theUnited States Department of Defense for Operationally Responsive Space. SpaceWire initiatives are being coordinated between several space agencies in the frame ofConsultative Committee for Space Data Systems (CCSDS) in order to extend its communication model to the network and transport layers of theOSI model.
SpaceWire supports highlyfault-tolerant networks and systems, which is one reason for its popularity.[5]
The ESA has a draft specification in place for the Protocol ID.
The following Protocol ID's have been assigned in ECSS-E-ST-50-51C:
| Protocol ID | Name | Description |
|---|---|---|
| 1 | Remote Memory Access Protocol (RMAP) | used to remotely access/alter register configuration of the devices |
| 2 | CCSDS Packet Transfer Protocol[6] | a common protocol used for sending Telecommands and receiving Telemetry |
| 238 | Proposal forReliable Data Delivery Protocol (RDDP) | used onGOES-R |
| 239 | Serial Transfer Universal Protocol (STUP) | Used on SMCS-332ASIC |
chapter 3.3.5
| Instruments and sensors |   | |
|---|---|---|
| Elements | ||
| Stages |
| |
| Images |
| |
| Discoveries |
| |
| Institutions | ||
| Related |
| |
