Chapter 1 Preamble The guiding principle in the teaching and research agenda related to embedded systems is bringing closer together system theory and computer science The two fields have drifted apart for years while we believe that the core of embedded systems intended as an engineering discipline lies in the marriage of the two approaches While computer science traditionally deals with abstractions where the physical world has been carefully and artfully hidden to facilitate the development of application software system theory deals with the physical foundations of engineering where quantities such as time power and size play a fundamental role in the models upon which this theory is based The issue then is how to harmonize the physical view of systems with the abstractions that have been so useful in developing the CS intellectual agenda We argue that a novel system theory is needed that at the same time is computational and physical The basis of this theory cannot be but a set of novel abstractions that partially expose the physical reality to the higher levels and methods to manipulate the abstractions and link them in a coherent whole The research community is indeed developing some of the necessary results to build this novel system theory We believe it is time to inject these findings in the teaching infrastructure so that students can be exposed to this new way of thinking By the same token the practitioners should also be exposed to these results that advance the state of embedded system design to a point where reliable and secure distributed systems can be designed quickly inexpensively and with no errors This book is intended to cover the fundamentals of embedded system design as they have been developed over the years by the research and industrial community Being exhaustive is certainly impossible given the many important contributions and the many industrial and scientific domains the field includes We chose to follow an organization for the contents of the book that stems out of a methodology Platform Based Design that has been proposed in various forms by several people and that seems to apply well to a wide variety of design problems The organization of the book reflects the organization of a graduate course EE249 Embedded System Design Modeling Analysis and Synthesis In US Universities bottom up aggregation of interests and approaches to education is more common than top down planning Hence education initiatives in novel areas almost always start with advanced graduate course offerings to migrate towards coordinated graduate programs and eventually into undergraduate courses Thus it is no wonder that course offering in Berkeley on embedded systems has been strong for years in the advanced course series the EE and CS 290 series that are related to faculty research activities EE249 indeed started more than ten years ago as an advanced 7 8 CHAPTER 1 PREAMBLE course and then migrated in 1998 to a regular offering in the graduate program In these past ten years the research area and the course contents have solidified to a point that we feel confident could be used at both the graduate and junior senior level For this reason we mark sections that in our opinion would be best covered in a graduate course and left out in an undergraduate course While the book has been designed having in mind its adoption as a textbook we feel that it could be used as a reference book for practicing engineers as well We would like to acknowledge the support of our families friends and colleagues during the writing of this book A special thank you goes to students who took EE249 and to the ones who helped teaching the class Chapter 2 Introduction This book is about the principles of system level design System Level Design SLD means many different things to many different people In our view system level design is about the design of a whole by assembling components where specifications are given in terms of functionality what the system is supposed to do for example a brake by wire automotive controller must actuate the braking action activated by the driver so that the wheels never lock with constraints on the properties the design has to satisfy for the brake by wire controller the braking action must be stable and on the components for the same example the embedded micro controller used in the implementation must be more reliable than a given threshold and objective functions that express the desirable features of the design when completed for example low overall manufacturing cost of the controller This definition is general since it relates to many different application domains from semiconductors to systems such as cars and airplanes buildings telecommunication and biological systems In this book we focus on a particular but very wide area embedded system design With the term embedded systems we refer to the electronic components which almost always include one or more software programmable parts of a wide variety of personal or broad use devices e g a mechanical system such as an automobile a train a plane an electrical system such as an electrical motor or generator a chemical system such as a distillation plant a health care equipment such as a pace maker Hence an embedded system is a special purpose system in which the computing element is completely encapsulated by the device it controls Unlike a general purpose computer an embedded system performs one or a few pre defined tasks usually with very specific requirements 110 In technical terms an embedded system interacts with the surrounding environment in a controlled way satisfying a set of requirements on responsiveness in terms of quality and timeliness Typically it has to satisfy implementation requirements such as cost power consumed and use of limited physical resources Ideally its interaction with the environment should be continuously available for the entire life of the artifact Design tools have been important to deliver exponential increase in integrated circuit complexity with much improved designers productivity An entire industry the Electronic Design Automation EDA industry reached maturity in the 1980s EDA today offers a rich tool set and flows for IC and board design The same level of maturity has not been reached in the embedded system design tool domain 9 10 CHAPTER 2 INTRODUCTION There are some notable companies in the space e g the Mathworks but an agreed upon flow and tool set has not emerged as yet
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