This paper addresses the design of reactive real-time embedded systems. Such systems are often heterogeneous in implementation technologies and design styles, for example by combining hardware ASICs with embedded software. The concurrent design process for such embedded systems involves solving the specification, validation, and synthesis problems. We review the variety of approaches to these problems that have been taken.

... This paper introduces the reader to various aspects of co-design. We highlight the commonalities and point out the differences in various co-design problems in some application areas. Co-design issues and their relationship to classical system implementation tasks are discussed to help the reader develop a perspective on modern digital system design that relies on computer-aided design (CAD) tools and methods.

The science of computation has systematically abstracted away the physical world. Embedded software systems, however, engage the physical world. Time, concurrency, liveness, robustness, continuums, reactivity, and resource management must be remarried to computation. Prevailing abstractions of computational systems leave out these "non-functional" aspects. This chapter explains why embedded software is not just software on small computers, and why it therefore needs fundamentally new views of computation. It suggests component architectures based on a principle called "actor-oriented design," where actors interact according to a model of computation, and describes some models of computation that are suitable for embedded software. It then suggests that actors can define interfaces that declare dynamic aspects that are essential to embedded software, such as temporal properties. These interfaces can be structured in a "system-level type system" that supports the sort of design-time and run-time type checking that conventional software benefits from.

Deep sub-micron processing technologies have enabled the implementation of new application-specificembeddedarchitecturesthat integrate multiple software programmable processors (e.g. DSPs, microcontrollers) and dedicated hardware components together onto a single cost-efficient IC. These application-specific architectures are emerging as a key design solution to today's microelectronics design problems, which are being driven by emerging applications in the areas of wireless communication, broadband networking, and multimedia computing. However, the constructionof these customized heterogeneous multiprocessor architectures, while ensuring that the hardware and software parts communicate correctly, is a tremendously difficult and highly error proned task with little or no tool support. In this paper, we present a solution to this embedded architecture cosynthesis problem based on an orchestrated combination of architectural strategies, parameterized libraries, and software tool support....

Both timing and functional properties are essential to characterize the correct behavior of an embedded system. Verification is in general performed either by simulation, or by bread-boarding. Given the safety requirements of such systems, a formal proof that the properties are indeed satisfied is highly desirable. In this paper, we present a formal verification methodology for embedded systems. The formal model for the behavior of the system used in POLIS is a network of Codesign Finite State Machines. This model is translated into automata, and verified using automatatheoretic techniques. An industrial embedded system is verified using the methodology. We demonstrate that abstractions and separation of timing and functionality is crucial for the successful use of formal verification for this example. We also show that in POLIS abstractions and separation of timing and functionality can be done by simple syntactic modification of the representation of the system.

This dissertation presents methods for automating the synthesis of embedded systems, i.e., special-purpose computers. In addition, it describes a method for analyzing the manner in which real-time operating system use influences embedded system power consumption.

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Task scheduling for reactive real time systems is a di#cult problem due to tight constraints that the schedule must satisfy. A static priorityscheme is proposed here that can be formally validated. The method is applicable both for preemptive and non-preemptiveschedules and is conservative in the sense that a valid schedule maybe declared invalid, but no invalid schedule maybe declared valid. Experimental results show that the run time of our validation method is negligible with respect to other steps in system design process, and compares favorably with other methods of schedule validation. 1 Introduction There is no universally accepted formal model for embedded systems, or even a universally accepted de#nition of which systems are considered embedded. In our approach, a system is considered embedded if it has the following characteristics: reactive: We consider systems consisting of many tasks which are executed in reaction to some external events, or to some other ta...

Existing methods for the design of application-specific instruction-set processors are tailored to the domain of data-dominated applications, which are characterized by extensive computations and few branches. In this paper we propose to combine a selection of current data-dominated design methods to form an integrated design methodology. Design methods for the control-dominated area require an extended set of information on application characteristics in order to effectively handle many branches intersected with only small data-flow blocks. Therefore, we introduce a multi-layer application representation that captures control, data, and timing dependencies as well as further annotations, to form a basis for transferring the methodology to the control-dominated domain. Based on this representation, we propose a method to resolve scheduling conflicts between tight deadlines. This method demonstrates the potential of the new representation.

This paper presents a system level specification for codesign of control modules and function modules in multimedia applications which have significant computational requirements as well as complex control systems. In the proposed compositional approach, control modules and function modules are separately described with extended FSM, called fFSM, and dataflow respectively, and integrated in the top-level codesign backplane. The codesign backplane supports interaction requirements between control and function modules, enables cosimulation of their composition, and will provide cosynthesis. Since fFSM and dataflow models are formal models of computation, we can analyze the specification of each module. Comparison with previous approaches and preliminary experiments show novelty and practicality of the proposed technique.