0018-9162/07/$25.00 © 2007 IEEE42 Computer Published by the IEEE Computer SocietyCOVER FEATURErequirements capture and OEM-issued specificationsconsisted of the message interface’s periods and generalperformance requirements, but without a detailed defi-nition of timing and synchronization properties and ofthe communication protocols’ requirements. As a result,the integration of subsystems is done routinely, albeit ina heuristic and ad hoc way. The resulting lack of an over-all understanding of the subsystems’ interplay, and thedifficulties encountered in integrating very complex parts,make system integration a very challenging job. The “CarElectronics Architecture” sidebar provides more infor-mation on the complexity of modern architectures.CHALLENGESNovel methods and tools for system-level analysis andmodeling are needed not only for predictability andcomposability when partitioning end-to-end functions atdesign time (and later, at system integration time), butalso for providing guidance and support to the designerin the very early stage where the electronics and soft-ware architectures of product lines are evaluated andselected. The critical architecture-evaluation and -selec-tion design-process phase affects profoundly a productline’s cost, performance, and quality.Architecture selection typically is performed years inadvance of subsystem development and integration. Inthis process, models of the functions and possible solu-tions for the physical architecture must be defined andmatched to evaluate quality and select the best possi-ble hardware platform with respect to performance,reliability, and cost metrics and constraints.To optimize the system design and allow for plug-and-play of subsystems,automotive electronic system architecture evaluation and development must be supported with arobust design flow based on virtual platforms.Alberto Sangiovanni-Vincentelli, University of California, BerkeleyMarco Di Natale, Scuola Superiore S. Anna, PisaToday, though still relatively stable, the roles ofcarmakers and their suppliers are undergoing aperiod of stress caused by the increased impor-tance and added value of electronics. The auto-motive supply chain includes car manufacturers—or OEMs—such as GM, Ford,DaimlerChrysler, and Toyota, who provide the finalproduct to the consumer market; Tier 1 suppliers—such as Bosch, Contiteves, Siemens,Nippondenso, Delphi, and Magneti Marelli—thatprovide subsystems such as power train management,suspension control, and brake-by-wire devices toOEMs; Tier 2 suppliers—chip manufacturers such asFreescale, Infineon, ST, and Renesas; IP providers suchas ARM; and real-time operating system supplierssuch as WindRiver and ETAS—who serve bothOEMs and Tier 1 suppliers; and manufacturing suppliers such as Flextronics andTSMC.Because of liability issues, automakers generally limitoutside manufacturing to non-safety-critical verticals.The standard approach for OEMs is to develop systemsby assembling components that have been completelyor partly designed and developed by Tier 1 suppliers.However, these suppliers increasingly are shiftingtoward outsourcing their manufacturing.The supply process traditionally has been targeted atsimple, black-box integrated subsystems in whichEmbeddedSystem Design forAutomotive ApplicationsOctober 2007 43Given the high cost of research, training,and possibly license acquisition for system-level design, using a coherent set of models,methods, and tools during a product’s orplatform’s entire lifetime is desirable. Thisextends from the architecture-analysis stageto system partitioning and design, andincludes model-based development, with itsautomatic middleware and application codegeneration steps, and the final integration,testing, and validation stages.Optimizing automotive electronics systemdesign requires standards in the software andhardware domains that allow for plug-and-play of subsystems. The ability to integratesubsystems will then become a commodityitem, available to all OEMs. An OEM’s com-petitive advantage will increasingly rely onnovel and compelling functionalities. Theessential technical problem to solve for thisvision is the establishment of standards forinteroperability among IPs—both softwareand hardware—and tools. AUTOSAR,1aworldwide consortium of most of the play-ers in the automotive domain electronicssupply chain, has this goal clearly in mind.However, technical and business chal-lenges must first be overcome. In particular,from a technical viewpoint, while sharingalgorithms and functional designs seems fea-sible at this time, the sharing of safety-criti-cal and hard real-time software is difficult,even assuming substantial improvements indesign methods and technology. Severalissues must be resolved for function parti-tioning and subsystem integration in thepresence of real-time and reliability require-ments. These include the following: Time predictability. This issue relates tothe capability of predicting the system-level timing behavior (latencies and jit-ter) resulting from the synchronizationbetween tasks and messages, as well asfrom the interplay that different tasks canhave at the real-time operating system(RTOS) level and the synchronizationand queuing policies of the middleware.The timing of end-to-end computationsdepends, in general, on the deploymentof the tasks and messages on the targetarchitecture and on the resource man-agement policies. Dependability. Deploying functions ontothe system engine control units (ECUs)and determining communication and syn-Car Electronics Architecture A typical modern vehicle contains between a dozen and nearly100 electronic control units (ECUs).1Current electronics systemsare typically partitioned by domains. There are two main classes ofelectronic systems: hard-real-time control of mechanical parts andinformation-entertainment. The first category includes• chassis control;• automotive body, including components such as interior air conditioning, dashboard, power windows, and controlsubsystems;• powertrain, including the engine, transmission, and emissionand control systems; and• active safety control.The second category includes information management, naviga-tion, computing, external communication, and entertainment.Each domain has its own requirements for computation speeds,time scales, reliability, flexibility, and extensibility. Today, power-train applications pose the most demanding