C O V E R F E A T U R E Embedded System Design for Automotive Applications Alberto Sangiovanni Vincentelli University of California Berkeley Marco Di Natale Scuola Superiore S Anna Pisa To optimize the system design and allow for plug and play of subsystems automotive electronic system architecture evaluation and development must be supported with a robust design ow based on virtual platforms T oday though still relatively stable the roles of carmakers and their suppliers are undergoing a period of stress caused by the increased importance and added value of electronics The automotive supply chain includes car manufacturers or OEMs such as GM Ford DaimlerChrysler and Toyota who provide the nal product to the consumer market Tier 1 suppliers such as Bosch Contiteves Siemens Nippondenso Delphi and Magneti Marelli that provide subsystems such as power train management suspension control and brake by wire devices to OEMs Tier 2 suppliers chip manufacturers such as Freescale In neon ST and Renesas IP providers such as ARM and real time operating system suppliers such as WindRiver and ETAS who serve both OEMs and Tier 1 suppliers and manufacturing suppliers such as Flextronics and TSMC Because of liability issues automakers generally limit outside manufacturing to non safety critical verticals The standard approach for OEMs is to develop systems by assembling components that have been completely or partly designed and developed by Tier 1 suppliers However these suppliers increasingly are shifting toward outsourcing their manufacturing The supply process traditionally has been targeted at simple black box integrated subsystems in which 42 Computer requirements capture and OEM issued specifications consisted of the message interface s periods and general performance requirements but without a detailed de nition of timing and synchronization properties and of the communication protocols requirements As a result the integration of subsystems is done routinely albeit in a heuristic and ad hoc way The resulting lack of an overall understanding of the subsystems interplay and the dif culties encountered in integrating very complex parts make system integration a very challenging job The Car Electronics Architecture sidebar provides more information on the complexity of modern architectures CHALLENGES Novel methods and tools for system level analysis and modeling are needed not only for predictability and composability when partitioning end to end functions at design time and later at system integration time but also for providing guidance and support to the designer in the very early stage where the electronics and software architectures of product lines are evaluated and selected The critical architecture evaluation and selection design process phase affects profoundly a product line s cost performance and quality Architecture selection typically is performed years in advance of subsystem development and integration In this process models of the functions and possible solutions for the physical architecture must be de ned and matched to evaluate quality and select the best possible hardware platform with respect to performance reliability and cost metrics and constraints Published by the IEEE Computer Society 0018 9162 07 25 00 2007 IEEE Given the high cost of research training and possibly license acquisition for systemlevel design using a coherent set of models methods and tools during a product s or platform s entire lifetime is desirable This extends from the architecture analysis stage to system partitioning and design and includes model based development with its automatic middleware and application code generation steps and the final integration testing and validation stages Optimizing automotive electronics system design requires standards in the software and hardware domains that allow for plug andplay of subsystems The ability to integrate subsystems will then become a commodity item available to all OEMs An OEM s competitive advantage will increasingly rely on novel and compelling functionalities The essential technical problem to solve for this vision is the establishment of standards for interoperability among IPs both software and hardware and tools AUTOSAR 1 a worldwide consortium of most of the players in the automotive domain electronics supply chain has this goal clearly in mind However technical and business challenges must rst be overcome In particular from a technical viewpoint while sharing algorithms and functional designs seems feasible at this time the sharing of safety critical and hard real time software is dif cult even assuming substantial improvements in design methods and technology Several issues must be resolved for function partitioning and subsystem integration in the presence of real time and reliability requirements These include the following Time predictability This issue relates to the capability of predicting the systemlevel timing behavior latencies and jitter resulting from the synchronization between tasks and messages as well as from the interplay that different tasks can have at the real time operating system RTOS level and the synchronization and queuing policies of the middleware The timing of end to end computations depends in general on the deployment of the tasks and messages on the target architecture and on the resource management policies Dependability Deploying functions onto the system engine control units ECUs and determining communication and syn Car Electronics Architecture A typical modern vehicle contains between a dozen and nearly 100 electronic control units ECUs 1 Current electronics systems are typically partitioned by domains There are two main classes of electronic systems hard real time control of mechanical parts and information entertainment The rst category includes chassis control automotive body including components such as interior air conditioning dashboard power windows and control subsystems powertrain including the engine transmission and emission and control systems and active safety control The second category includes information management navigation computing external communication and entertainment Each domain has its own requirements for computation speeds time scales reliability exibility and extensibility Today powertrain applications pose the most demanding challenge in terms of real time constraints and computational power with activation period requirements going down to a few milliseconds at high