INTEGRATED ONBOARD NETWORKING FOR IMA2G Yuriy Sheynin*, Elena Suvorova*, Valentin Bukov**, Vladimir Shurman** *) Saint-Petersburg State University of Aerospace Instrumentation Saint-Petersburg, Russian Federation **) PLC Scientific and Research Institute of Avionic Equipment Zshukovsky, Moscow Region, Russian Federation Keywords: IMA2G, SpaceWire, Zero Maintenance Equipment, Integrated Networking Architecture Abstract Tools) project, [1] has shown, the AFDX The article presents developments of be the IMA2G integrated networking next generation onboard networking for interconnection. With its optimized for IMA2G that is based on the SpaceWire/GigaSpaceWire networking throughput architecture and protocols it has poor latency para technology. The IMA2G prospective vision requirements of time-critical fast-loop could be further strengthen by its integration applications where low latency is the with the Zero Maintenance Equipment (ZME) concepts. The article describes the SpaceWire predominant requirement. As a result, for such based backbone network as an integral parts of the distributed on-board architecture interconnection for IMA2G, gives examples with low latency & short period of applying typical avionics subsystems on requirements, the AFDX networking is SpaceWire based interconnection. reduced to so-called LC-AFDX (Low Capacity AFDX), [2], Field-bus in fact, reduced from scalable switch-based networking back to point-to- 1 Introduction point interconnections. An IMA2G networking technology should IMA2G should cover broader scope of support broad scalability in all domains: in avionics units and subsystems not only data number of nodes, in data rates, in throughput, computing resources. It should move to in latency constraints. Scalability should not distributed computing entity (unlike typically only give a way for reconfiguration, central computing resources in IMA1G), and increase(decrease) number of nodes and cover command/control, signal processing, IO integrated avionics resources gain, but resources also . It sets new requirements for an support structured isoefficiency in avionics backbone network as the IMA2G interconnection characteristics also. Packet integral interconnection. IMA2G backbone delivery and signaling latency should be network as an integral interconnection confined in required bounds. Scalability of should be able to provide all types of traffic network integral throughput should be in onboard avionics, substituting the separate accompanied by statistical equidistance of end and heterogeneous sensor busses, data busses, nodes and keeping bilateral throughput command busses, field busses and sideband between them in scaling network structure. It signals for time stamps distribution and hard would be vital for true flexibility of function real-time signaling. allocation that is claimed to be one of the As the SCARLETT (SCAlable & IMA2G key features. Real-time signaling with ReconfigurabLe Electronics plaTforms and 1 YURIY SHEYNIN et al. strict latency constraints is important for support all types of traffic in the distributed on- synchronization, control in the loop, control board avionics, Table 1: signaling. Sensor buses with high-rate data streams between digitized signals sources and receivers; 2. Integrated Networking for IMA2G Command buses, that needs to deliver Evolution of integrated modular avionics command packets with deterministic from IMA1G to IMA2G is transition to delivery time; integrated architecture on-board systems. Target Data buses for distributed processing, with systems of an aircraft would not be isolated low latency delivery of data packets; subsystems, with boundaries implemented in Signal lines with hard real-time signals hardware and software structure of on-board distribution with ultra-low latency for equipment. They would become virtualised and synchronisation and control. distributed over on-board equipment structure. On-board processing, data acquisition and Table 1. Airborne interconnections communication facilities should form an Bussing Current bussing Prospective integral pull of resources for all the set of examples alternative aircraft on-board systems target tasks. From autonomous computers in the Sensor Fibre Channel SpaceWire/ federative architecture we move to an integrated buses (FC) GigaSpaceWire computing entity for data and signal processing. Command MIL-STD SpaceWire, Logical boundaries between target systems buses 1553B SpaceWire-D, would not be reflected in a structure of on-board SpaceFibre processing and communication infrastructure. Further integration in IMA2G should cover data Data buses AFDX SpaceWire, processing in a distributed modular electronics (Ethernet), GigaSpaceWire, (DME) architecture, as well as command and SRIO SpaceFibre control, I/O and signalling tasks. DME will have scalable distributed computing by integral Video ARINC818, SpaceWire, computing environment. IO would be separated buses FC-AV GigaSpaceWire, from computing modules and could be SpaceFibre positioned anywhere in the distributed Field buses SPI, I2C SpaceWire architecture. Real-time constraints in IO CAN, RS485, signaling and control should not lead to physical RS422 binding them to particular modules but could be distributed over the DME structure and could Time Proprietary SpaceWire migrate in system reconfiguration. synchronis bussing Reconfiguration mechanisms would work in ation virtually integral computing environment while busses being physically distributed and spread over the Sideband Proprietary, SpaceWire aircraft. These key features should be supported signals unit-specific in distributed computer architecture, system wiring, multiple software and scalable onboard networking wires interconnection. DME on-board architecture should move towards integral interconnection infrastructure, The Integrated Networking ARchitecture should be supported by an Integrated (INAR) for IMA2G and AZME has been Communications Network (ICN). It should developed, which is based on provide a communication entity that could 2 INTEGRATED ONBOARD NETWORKING FOR IMA2G SpaceWire/GigaSpaceWire networking common time codes distribution, distributed technology, [3]. interrupt signals. Its components, e.g. The INAR gives a basis for building scalable SpaceWire NIC in end nodes, is very networking infrastructure with compact and compact in VLSI implementation and could light-weight routing switches, ready for be integrated into any types of nodes scalability and duplications for redundancy. It from computing nodes to simple sensor and provides high rate communications (up to 400 actuator chips/SiP. Further SpaceWire Mbit/s for SpaceWire, 1-5 Gbit/s for technology developments GigaSpaceWire, GigaSpaceWire links), better latencies than [6], SpaceFibre/SpaceWire-RT, give higher other networking technologies, efficient and rates (1-10 Gbit/s), longer links (to 100-200 m), compact implementation in chips. galvanic isolation, extended QoS features, [7]. INAR provides integral network GigaSpaceWire defines DC-balanced links with infrastructure for all types of traffic in DME: 8B10B coding and galvanic isolation options. high-rate data streams, command packets with The SpaceWire standard does not set any deterministic delivery time, data packets for limitations on the packet size. This feature can distributed processing and IO, common time be used for support of unpacketized data stream ticks distribution, ultra-low latency distribution (e.g. raw radar digital signal stream) or large of hard real-time signals. Interfacing INAR to packets for data streams with huge data items other interconnections (ARINC429, CAN, (e.g. video frames), in SpaceWire based AFDX, FibreChannel) for gradual evolution of communication infrastructures for on-board avionics is provided by gateway nodes. systems. In our design we included ability to, frame the incoming byte stream, supply it with an adequate packet descriptor type, format it as 3. INAR networking with the SpaceWire a packet, and send by the link to the network. technology Thus, we can do an entrance packetizing of a raw data stream. It could be a useful feature to The SpaceWire networking technology communicate with devices, which has not development was launched by the ESA information flow packetizing facilities inside initiative and has been done by the them. international SpaceWire WG that was formed Another SpaceWire important feature is and coordinated by the ESTEC/ESA. The first hard real-time signaling support. release of the SpaceWire standard had been These features correlate well with published in January 2003 (the current release prospective avionics IMA2G requirements. 2008, [4]). Nowadays SpaceWire is the Based on SpaceWire spacecraft on-board mature technology, it is supported by ESA, equipment integrated modular architecture is NASA, Roscosmos, JAXA; it has been used presented at the Fig.1. in a number of national satellites and Modern on-board systems use packetized spacecrafts and in international missions, [5]. digital streams flows to deliver signals and data SpaceWire defines full protocol stack- to and from sources and receivers. The switched from physical level to network level (in the SpaceWire/GigaSpaceWire digital signal links accompanying standards the Transport level offers: also). It uses high-rate serial duplex links increase of a distance from channels with low power consumption LVDS sensors/effectors to ISDS modules up to signals and automatic transfer rate adaptation any reasonable for on-board systems with continues