Post on 03-Feb-2021
AOE7 - Central Engineering Data-processing and Software Division
Data Links and Networks in Space Applications – SpaceWire usageSpaceWire 4th Workshop, ESTEC, July 2005Olivier Notebaert - Data Processing and SW advanced studies
Page 2 SpaceWire Data Links and Networks in Space Applications
AOE7 - Central Engineering Data-processing and Software Division
20/07/2005
SUMMARY
On-board data communications contextSpace Systems Constraints and RequirementsData Processing Functions and TrendsTrade-offsData processing architectures
Usage of SpaceWire in space applicationsCurrent usage of high speed data linksAdvanced data processing architecture studiesIssues for best usage of SpaceWire networks
Conclusion
Page 3 SpaceWire Data Links and Networks in Space Applications
AOE7 - Central Engineering Data-processing and Software Division
20/07/2005
DATA COMMUNICATIONS CONTEXTSpace Systems Constraints
Harsh environmentRadiations | Vibrations | Shocks | Thermal effects…
Induces high costs for development and qualification programsMission and phase dependant (launch | Low Earth Orbit | Geostationary | Deep space…)Limited resources in space for embedded electronics
Communication Link- Availability and delays of ground/spacecraft communications- This induces on-board data-handling support functions (data compression,
storage, retrieval, autonomous monitoring and control…)
Power budget is strictly limited (electrical and propulsion)Mass and volume needs to be minimized (launch cost, life-time…)
Reduced choice of electronic components and available technologies
Need for concentrating the development efforts on a limited set of standardized and perennial solutions
Page 4 SpaceWire Data Links and Networks in Space Applications
AOE7 - Central Engineering Data-processing and Software Division
20/07/2005
DATA COMMUNICATIONS CONTEXTSpace Systems Requirements
Mission dependant systems requirementsCommand and ControlFailure Detection Isolation and RecoveryPerformances of spacecrafts bus and instrumentsReliabilityAvailabilitySafetyOperational and maintenance requirementsQualification levels
Various range of requirements induces numerous specific solutions for the Data Processing Systems architecture and products
Need for flexible generic architectures based on a limited set of common HW and SW building blocks
Page 5 SpaceWire Data Links and Networks in Space Applications
AOE7 - Central Engineering Data-processing and Software Division
20/07/2005
DATA COMMUNICATIONS CONTEXTData processing functions and trends
P/L Science data cannot be downlinked at acquisition rateIncreasing need for high performance on-board data processing (e.g. compression, formatting, filtering…)Increasing need for high capacity on board data storage
Several independent instruments on a same spacecraftWith high rate data linksWith low rate command and control
Telecommunication data switching requires higher performance dynamic control (for e.g. telephone, internet…)Growing need for on-board intelligence (AOCS, camera, radar, robotics, navigation…) resulting in data rate increaseTM/TC and on-board data require increased security functions
Page 6 SpaceWire Data Links and Networks in Space Applications
AOE7 - Central Engineering Data-processing and Software Division
20/07/2005
DATA COMMUNICATIONS CONTEXTTrade-offs
Critical trade-off in the implementation of space systemsTechnologies adaptation to environmental constraints Quality of payload dataOn-board processing performanceData transmission delays and synchronisation of distant unitsRedundancies of elements and data linksPower consumption, Overall Weight/length of cablesOverall cost …
Efficiency of the data links solutions depend on the systems priorities and of the nature of the transmitted data
This results in several types of data linksCommand and control buses (OBDH, 1553, Can)Point to point serial data links (RS232, RS422, 1355, SpaceWire,…)Discrete dedicated interfaces (Direct commands, sensor acquisition…)
Page 7 SpaceWire Data Links and Networks in Space Applications
AOE7 - Central Engineering Data-processing and Software Division
20/07/2005
DATA COMMUNICATIONS CONTEXTTypical data processing architecture
Typical resulting on-board data processing architectureIndependent instruments data processing unitsDirect interfaces to Mass Memory for high rate data storageInstrument control through system bus and Remote Terminal Units (RTU)Several types of data links adapted to communication needs
Low rateDigital I/F
-DiscreteInterface
High rateDigital I/F
Low rateDigital I/F
-DiscreteInterface
Control &Monitoring
drivers
Sensors
Mechanisms
Thermal
InstrumentData
ProcessingUnit
Instrument electronics
Mass MemoryUnit
RTUelectronics
System bus
High rateDigital I/F
Low rateDigital I/F
-DiscreteInterface
OBMU
TFG
Spacecraft DataProcessing
Unit
Compromise between system requirement, available technology and signals characteristics
Page 8 SpaceWire Data Links and Networks in Space Applications
AOE7 - Central Engineering Data-processing and Software Division
20/07/2005
DATA COMMUNICATIONS CONTEXTAlternate data processing architecture
Dedicated to improve the system budget issues:Lower number of nodes and links variantsShare of common functions/resourcesInstrument connected to SpaceWire Network through Remote Terminal Interface (RTI)
DigitalInterface
(Spacewire)
DigitalInterface
(Spacewire)Control &Monitoring
drivers
Sensors
Mechanisms
Thermal
First-stageData
Processing
SpacewireRouting unit
Shared DPUInstrument electronics
Mass MemoryUnit
Data ProcessingUnit
To TFG
To/fromS/C
RemoteTerminalInterface
SpaceWire Networks could be an element for improvement of futureon-board data processing architecture and overall budgets
Page 9 SpaceWire Data Links and Networks in Space Applications
AOE7 - Central Engineering Data-processing and Software Division
20/07/2005
USAGE OF SPACEWIRE IN SPACE APPLICATIONSCurrent usage of high speed data links
1355 links used in several spacecrafts such asScience data to Mass Memory (Cryosat, Rosetta, Mex/Vex)For telecom signal dynamic switching (Inmarsat4)
Other High data rate links used for Gbits performance requirements (Pleiades, TerraSAR-X)Also used as OBC ground test interface for software instrumentation (Pleiades, TerraSAR-X)SpaceWire used in most studies on future data processing architecture and Leon SoC prototypes
ESA studies (e.g SCoC and the A3M demonstrator, A3SysDef, Gamma, Disco…)National agencies and EADS-Astrium internal projects (ALF3, Unionics, MAEVA,…)
Page 10 SpaceWire Data Links and Networks in Space Applications
AOE7 - Central Engineering Data-processing and Software Division
20/07/2005
DATA PROCESSING ARCHITECTURE STUDIESAvionics Advanced Architecture and Modules (A3M)
The A3M architecture includes fault tolerance mechanismsDemonstrator includes three Spacecraft Controller on a ChipBi-directional SpaceWire links used for inter-node data synchronisation
FPGA
LEON
SPW SPW
BLADE cPCI board
FPGA
LEON
SPW SPW
BLADE cPCI board
SRAM
FPGA
LEON
SPW SPW
BLADE cPCI board
bi-directional SpaceWire links
Two serial links / board:-VxWorks console-PPP interface (IP link)
LINUX PC
SRAMSRAM
ETHERNET LAN
3 x 2RS232seriallinks
Linux PC
Bootmanager
OBC cPCI subrack
3SpaceWire
links
Page 11 SpaceWire Data Links and Networks in Space Applications
AOE7 - Central Engineering Data-processing and Software Division
20/07/2005
DATA PROCESSING ARCHITECTURE STUDIESAvionics Advanced Architecture and Modules (A3M)
The A3M study conclusions on SpaceWireVery efficient for inter-processor communication :
With intelligent controllers, very highdata rate can be achieved frommemory to memoryEfficient implementation of protocolsatop SpaceWire requires to limit thenumber of SW layersThe software must take into accountthe flow control mechanism in orderto avoid overload propagation fromone processor to the othersCommunication time is generally small compared to the processing time required to manage a message.
SpaceWire communicationperformance
0 µs
500 µs
1 000 µs
1 500 µs
2 000 µs
2 500 µs
3 000 µs
0 500 1000 1500
packet size (bytes)µs
/ ca
ll
80 Mbit/s
40 Mbit/s
20 Mbit/s
10 Mbit/s
40 Mbit/s withoutcache
Page 12 SpaceWire Data Links and Networks in Space Applications
AOE7 - Central Engineering Data-processing and Software Division
20/07/2005
DATA PROCESSING ARCHITECTURE STUDIESAurora Avionics Architecture System Definition (A3SysDef)
Definition of a generic functional architecture for planetary exploration missionsHigh speed data-links between standard functional unitsTrade-off performed between:
PacketWire (10 Mbps, LVDS)SpaceWire (200 Mbps, LVDS)GIGABIT SpaceWire (1 Gbps, LVDSor optical)Ethernet 100baseT (100 Mbps, 1,5 Vpp)IEEE-1394 (400 Mbps, 265 mVpp)USB 2.0 (480 Mbps, 3.3 Vpp)PCI express (up to 2500 Mbps, 0,5 Vpp)
Conclusion : SpaceWire is selected for High Speed data network between on-board building blocks
TMTC
HDRP/L
HDRP/L
HDRP/L
LDRP/L
LDRP/L
LDRP/L
SpaceWirerouter
SSMM
PayloadSupport
Unit
SCC coreTM TFG
Platform units(AOCS, thermal, power, …)
µRTU
µRTU
µRTU
µRTU
µRTU
µRTU
SpaceWire
CAN
LDRSystem
Bus
Page 13 SpaceWire Data Links and Networks in Space Applications
AOE7 - Central Engineering Data-processing and Software Division
20/07/2005
DATA COMMUNICATIONS CONTEXTUNIONICS
Advanced architecture dedicated for High-performance on-board distributed processingModular and scalable architecture on SpaceWire networkSpecialized building blocks including:
Processor nodesSpaceWire RoutersMass Memory nodesSystem Watchdog
Demonstrator developedFurther works planned
FDIR consolidationProcessing node on Leon2Consolidation of SW modulesCase study implementationand evaluation (ExoMars Rover)
System Watchdog
MMU
MMUMMU
MMU
I/O
Fault Management Layer
ardware/Software Monitoring
nitiation of system reconfiguration
irect TM/TC bypassProcessing & Routing Layer
paceWire Network
ultiple processors
ardware redundant routers
I/O & Memory Layer
/O ports for various protocols
etwork ‘dumb’ nodes
ass data storage
PROC
PROC PROC
MMU
MMU
R R PROC
Watchdog TM/TC
I/O
I/OI/O
Page 14 SpaceWire Data Links and Networks in Space Applications
AOE7 - Central Engineering Data-processing and Software Division
20/07/2005
DATA PROCESSING ARCHITECTURE STUDIESGeneric Architecture for Mass Memory Access (Gamma)
Distributed architecture for data storage management.
Several memory users (Calculators, instruments, …)Several memory modules (and technologies)
Manage concurrent data accessesProtect transactionsEnsure data consistency
Demonstrator on a representative environment based on five identical commercial FPGA boards.
Use of SpaceWire network:40 Mbps at first, 80 Mbps and more expected.2 SpaceWire interfaces per boardto test concurrent accesses.
FPGAUser4
Router
FPGA
FPGA
FPGA
FPGA
User1
User2
Memory2
Memory1
Memory3
User3
GR-CPCI-XC2Vboards
6U
CPCI PC board(controller)
2xSUBD9(SpW)
SpW
SpW
SpW
SpW
SpW
SpW
SpW
SpWSpW router
2xDB9(RS232)
USB
RS232 interfaces LAN
Page 15 SpaceWire Data Links and Networks in Space Applications
AOE7 - Central Engineering Data-processing and Software Division
20/07/2005
USAGE OF SPACEWIRE IN SPACE APPLICATIONSIssues for best usage of SpaceWire networks
Availability of SpaceWire Network building blocks elementsSpace qualified components and IP’s for integration in SoC’sGround support software/hardware
adapters to ground networks (usb, ethernet…), Traffic monitor/simulator, network administration SW, simulation…
On-board Software issuesCommunication services / SOIS – HW/SW interfaceSupport of application distribution and resource sharing
FDIR issues:Failure modes of network building blocks (Routers, RTI’s)Support of Broadcast and Multicast modesSupport of time/memory data partitioning
Detailed evaluation of properties for SpaceWire networks (latency, propagation time, data security…)
Page 16 SpaceWire Data Links and Networks in Space Applications
AOE7 - Central Engineering Data-processing and Software Division
20/07/2005
USAGE OF SPACEWIRE IN SPACE APPLICATIONSConclusion
SpaceWire/ECSS-E50-12 supports the need for high performance data processing on future spacecrafts
To be recommended for any point-to-point high speed links under 200 Mbps
A higher data rate implementation (for instance through other physical media) would increase the usability domain
Viewed as a future solution toward more generic payload data processing systems through on-board data networks
Optimising on-board resources and performancesSome issues require consolidation (FDIR, communication services,development of SW and HW components, development tools)
Could also be extended to the whole data processing system (eg. for small vehicles, robotics…)
Data Links and Networks in Space Applications – SpaceWire usageSUMMARYDATA COMMUNICATIONS CONTEXTSpace Systems ConstraintsDATA COMMUNICATIONS CONTEXTSpace Systems RequirementsDATA COMMUNICATIONS CONTEXTData processing functions and trendsDATA COMMUNICATIONS CONTEXTTrade-offsDATA COMMUNICATIONS CONTEXTTypical data processing architectureDATA COMMUNICATIONS CONTEXTAlternate data processing architectureUSAGE OF SPACEWIRE IN SPACE APPLICATIONSCurrent usage of high speed data linksDATA PROCESSING ARCHITECTURE STUDIESAvionics Advanced Architecture and Modules (A3M)DATA PROCESSING ARCHITECTURE STUDIESAvionics Advanced Architecture and Modules (A3M)DATA PROCESSING ARCHITECTURE STUDIESAurora Avionics Architecture System Definition (A3SysDef)DATA COMMUNICATIONS CONTEXTUNIONICSDATA PROCESSING ARCHITECTURE STUDIESGeneric Architecture for Mass Memory Access (Gamma)USAGE OF SPACEWIRE IN SPACE APPLICATIONSIssues for best usage of SpaceWire networksUSAGE OF SPACEWIRE IN SPACE APPLICATIONSConclusion