Central Engineering / ASG 74 Data Processing Advanced Studies Sev Gunes-Lasnet, Olivier Notebaert 2008, November 5th Prototype implementation of a routing policy using FlexRay frames concept over a SpaceWire Network International SpaceWire conference 2008, Nara, Japan

This document is the property of Astrium. It shall not be communicated to third parties without prior written agreement. Its content shall not be disclosed. Central Engineering (ASG74) Data Processing Advanced Studies Prototype implementation of a routing policy using FlexRay frames concept over a SpaceWire Network 19/12/20062 Presentation outline  On-board data links optimisation  SpaceWire networks  Concepts from automotive industry  Prototype implementation  Conclusions and way further On-board data links optimisation SpaceWire networks Concepts from automotive industry Prototype implementation Conclusions and way further

This document is the property of Astrium. It shall not be communicated to third parties without prior written agreement. Its content shall not be disclosed. Central Engineering (ASG74) Data Processing Advanced Studies Prototype implementation of a routing policy using FlexRay frames concept over a SpaceWire Network 19/12/20063 On-Board Data links optimisation  Payload Data processing trends:  P/L Science data cannot be downlinked at acquisition rate  Increasing 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 spacecraft  With high rate data links  Growing need for on-board intelligence (AOCS, camera, radar, robotics, navigation…) resulting in data rate increase On-board data links optimisation SpaceWire networks Concepts from automotive industry Prototype implementation Conclusions and way further

This document is the property of Astrium. It shall not be communicated to third parties without prior written agreement. Its content shall not be disclosed. Central Engineering (ASG74) Data Processing Advanced Studies Prototype implementation of a routing policy using FlexRay frames concept over a SpaceWire Network 19/12/20064 Architecture trade-offs  In parallel, critical trade-offs are made in the implementation of space systems, due to:  Technologies adaptation to environmental constraints  On-board processing performance  Redundancies of elements and data links  Power consumption, Overall Weight/length of cables  Overall cost …  Efficiency of the data links solutions depends on the systems priorities and on the nature of the transmitted data  This results in several types of data links:  Command and control buses (OBDH, 1553, Can)  Point to point serial data links (RS232, RS422, 1355, SpaceWire,…)  Discrete dedicated interfaces (Direct commands, sensor acquisition…) On-board data links optimisation SpaceWire networks Concepts from automotive industry Prototype implementation Conclusions and way further

This document is the property of Astrium. It shall not be communicated to third parties without prior written agreement. Its content shall not be disclosed. Central Engineering (ASG74) Data Processing Advanced Studies Prototype implementation of a routing policy using FlexRay frames concept over a SpaceWire Network 19/12/20065 Typical data processing architecture  Typical resulting on-board data processing architecture  Independent instruments data processing units  Direct interfaces to Mass Memory for high rate data storage  Instrument control through system bus and Remote Terminal Units (RTU)  Several types of data links adapted to communication needs On-board data links optimisation SpaceWire networks Concepts from automotive industry Prototype implementation Conclusions and way further

This document is the property of Astrium. It shall not be communicated to third parties without prior written agreement. Its content shall not be disclosed. Central Engineering (ASG74) Data Processing Advanced Studies Prototype implementation of a routing policy using FlexRay frames concept over a SpaceWire Network 19/12/20066 Alternate data processing architecture: SpaceWire networks  Dedicated to improve the system budget issues:  Lower number of nodes and links variants  Share of common functions/resources  Budgets optimisation Spacewire as payload data handling network SpaceWire Networks are an element for improvement of future on- board data processing architecture and overall budgets On-board data links optimisation SpaceWire networks Concepts from automotive industry Prototype implementation Conclusions and way further

This document is the property of Astrium. It shall not be communicated to third parties without prior written agreement. Its content shall not be disclosed. Central Engineering (ASG74) Data Processing Advanced Studies Prototype implementation of a routing policy using FlexRay frames concept over a SpaceWire Network 19/12/20067 SpaceWire networks as Payload data handling building blocks  Development of SpaceWire networks  Determinism studies are necessary to guarantee the respect of timing and reliability constraints of spacecrafts  Development of standard protocols ensuring time deterministic packet delivery will enable the use of SpaceWire networks  SpaceWire networks development can benefit from the automotive spin- ins:  Safety/highly critical applications requirements  Availability of tools/products  Large user data base  Low cost  Thorough products validation On-Board network Benchmarking the automotive industry concepts and products is of high interest in the context of the development of standardised protocols over SpaceWire networks On-board data links optimisation SpaceWire networks Concepts from automotive industry Prototype implementation Conclusions and way further

This document is the property of Astrium. It shall not be communicated to third parties without prior written agreement. Its content shall not be disclosed. Central Engineering (ASG74) Data Processing Advanced Studies Prototype implementation of a routing policy using FlexRay frames concept over a SpaceWire Network 19/12/20068 Benchmarking concepts from automotive industry: Proposed strategy  Prefer a standard  Avoid monopolistic Supplier  Implement an obsolescence management plan  Market might not provide a solution on its own On-board data links optimisation SpaceWire networks Concepts from automotive industry Prototype implementation Conclusions and way further

This document is the property of Astrium. It shall not be communicated to third parties without prior written agreement. Its content shall not be disclosed. Central Engineering (ASG74) Data Processing Advanced Studies Prototype implementation of a routing policy using FlexRay frames concept over a SpaceWire Network 19/12/20069 Benchmarking concepts from automotive industry  Trends in automotive industry:  Synchronous & Asynchronous communication supported  Fault-tolereance, guaranteed latency, high speed capabilities are supported to target X-by-Wire applications (steer-by-wire & brake-by- wire)  Existing consortiums  FlexRay, TTP…  FlexRay consortium situation Initially, the consortium was only open to automotive industry players semiconductor manufacturers, equipment and system suppliers, tools and services suppliers and manufacturers In late 2006, the consortium agreed the membership to EADS CCR Germany as a move to non- automotive companies Technology use and licensing is still not cleared for non-automotive applications On-board data links optimisation SpaceWire networks Concepts from automotive industry Prototype implementation Conclusions and way further A customised pilote implementation has been chosen rather than the direct evaluation of automotive products

This document is the property of Astrium. It shall not be communicated to third parties without prior written agreement. Its content shall not be disclosed. Central Engineering (ASG74) Data Processing Advanced Studies Prototype implementation of a routing policy using FlexRay frames concept over a SpaceWire Network 19/12/ SpaceWire network protocol prototyping activity  Principle: Higher level protocols could be implemented over SpaceWire to ensure the respect of timing constraints, while respecting the SpaceWire standard  Prototyping of a higher level protocol using concepts from the automotive protocol FlexRay  Pilote implementation over a SpaceWire network allowing further analysis of the concept and performance assessment On-board data links optimisation SpaceWire networks Concepts from automotive industry Prototype implementation Conclusions and way further

This document is the property of Astrium. It shall not be communicated to third parties without prior written agreement. Its content shall not be disclosed. Central Engineering (ASG74) Data Processing Advanced Studies Prototype implementation of a routing policy using FlexRay frames concept over a SpaceWire Network 19/12/ Prototyping configuration  A time master on the network distributes a global time reference  Modules use this time reference for sending packets over the network  The configuration implements a priority based bandwidth reservation:  Packets with high priority are transmitted first during the static part of the cycle Time master Packets analysis Rosetta modules On-board data links optimisation SpaceWire networks Concepts from automotive industry Prototype implementation Conclusions and way further

This document is the property of Astrium. It shall not be communicated to third parties without prior written agreement. Its content shall not be disclosed. Central Engineering (ASG74) Data Processing Advanced Studies Prototype implementation of a routing policy using FlexRay frames concept over a SpaceWire Network 19/12/ Prototyping activity  Definition of a communication model over a SpaceWire network, with the following caracteristics:  Priority based packet transmission using bandwidth reservation slots during first part of the cycle  Cycle allows asynchronous communication during second half on the cycle On-board data links optimisation SpaceWire networks Concepts from automotive industry Prototype implementation Conclusions and way further

This document is the property of Astrium. It shall not be communicated to third parties without prior written agreement. Its content shall not be disclosed. Central Engineering (ASG74) Data Processing Advanced Studies Prototype implementation of a routing policy using FlexRay frames concept over a SpaceWire Network 19/12/ Prototyping activity  During first part of cycle  The router analyses and treats the incoming packets  Messages are sent using bandwidth reservation (slots) based on priority allocation  During second part of cycle, incoming packets are not reorganised by the router.  Reorganisation of packets during the first part of the communication cycle has been monitored On-board data links optimisation SpaceWire networks Concepts from automotive industry Prototype implementation Conclusions and way further

This document is the property of Astrium. It shall not be communicated to third parties without prior written agreement. Its content shall not be disclosed. Central Engineering (ASG74) Data Processing Advanced Studies Prototype implementation of a routing policy using FlexRay frames concept over a SpaceWire Network 19/12/ Prototyping further improvements  Increase the traffic between the modules.  Synchronisation method between the different modules  Precise attribution of communication slots to each node connected to the SpaceWire network.  Optimisation of the communication cycle  Length of the packets and of the communication cycle can be adapted.  Specification of dedicated router capabilities  Slots reservation for each user on the network,  Control of the packets transmission to prevent babbling idiot errors,  Further capabilities. On-board data links optimisation SpaceWire networks Concepts from automotive industry Prototype implementation Conclusions and way further

This document is the property of Astrium. It shall not be communicated to third parties without prior written agreement. Its content shall not be disclosed. Central Engineering (ASG74) Data Processing Advanced Studies Prototype implementation of a routing policy using FlexRay frames concept over a SpaceWire Network 19/12/ Future perpectives  The prototype allows  Investigations such as the measurement of the sensitivity of the latency wrt the length of packets transmitted over the network  The optimal dimensioning of the network elements:  Size of an internal router buffer (hardware complexity factor),  Optimal length of the communication cycle…  The platform used for this pilote implementation  Can be used for the evaluation of a further concept of real time protocol over a SpaceWire network On-board data links optimisation SpaceWire networks Concepts from automotive industry Prototype implementation Conclusions and way further

This document is the property of Astrium. It shall not be communicated to third parties without prior written agreement. Its content shall not be disclosed. Central Engineering (ASG74) Data Processing Advanced Studies Prototype implementation of a routing policy using FlexRay frames concept over a SpaceWire Network 19/12/ Conclusions and way forward  First implementation of concepts developed in the automotive industry over a SpaceWire networks  Communication cycle model defined allows both bandwidth static allocation and dynamic allocation  Router in charge of arbitration and bandwidth attribution  Existing SpaceWire sensors and actuators can be used without modifications due to specific RT requirements  Further prototype use  Optimal dimensioning of network elements  Evaluation of further concepts of real time protocols over SpaceWire networks On-board data links optimisation SpaceWire networks Concepts from automotive industry Prototype implementation Conclusions and way further