1 Introduction 2 Models and Architectures 3 Specification Languages 4 A Specification Example 5 Translation to VHDL 6 System Partitioning 7 Design Quality Estimation 8 Specification Refinement into Synthesizable Models 9 System-Design Methodology and Environment Appendix: Answering Machine in SpecCharts Bibliography Index

Specification and Design of Embedded Systems

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 application-specific integrated circuits (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.

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Design of embedded systems: formal models, validation, and synthesis

The main characteristic of Reconfigurable Computing is the presence of hardware that can be reconfigured to implement specific functionality more suitable for specially tailored hardware than on a simple uniprocessor. Reconfigurable computing systems join microprocessors and programmable hardware in order to take advantage of the combined strengths of hardware and software and have been used in applications ranging from embedded systems to high performance computing. Many of the fundamental theories have been identified and used by the Hardware/Software Co-Design research field. Although the same background ideas are shared in both areas, they have different goals and use different approaches.This book is intended as an introduction to the entire range of issues important to reconfigurable computing, using FPGAs as the context, or "computing vehicles" to implement this powerful technology. It will take a reader with a background in the basics of digital design and software programming and provide them with the knowledge needed to be an effective designer or researcher in this rapidly evolving field.

· Treatment of FPGAs as computing vehicles rather than glue-logic or ASIC substitutes
· Views of FPGA programming beyond Verilog/VHDL
· Broad set of case studies demonstrating how to use FPGAs in novel and efficient ways

Reconfigurable Computing: The Theory and Practice of FPGA-Based Computation

Clock distribution networks synchronize the flow of data signals among synchronous data paths. The design of these networks can dramatically affect system-wide performance and reliability. A theoretical background of clock skew is provided in order to better understand how clock distribution networks interact with data paths. Minimum and maximum timing constraints are developed from the relative timing between the localized clock skew and the data paths. These constraint relationships are reviewed, and compensating design techniques are discussed. The field of clock distribution network design and analysis can be grouped into a number of subtopics: 1) circuit and layout techniques for structured custom digital integrated circuits; 2) the automated layout and synthesis of clock distribution networks with application to automated placement and routing of gate arrays, standard cells and larger block-oriented circuits; 3) the analysis and modeling of the timing characteristics of clock distribution networks; and 4) the scheduling of the optimal timing characteristics of clock distribution networks based on architectural and functional performance requirements. Each of these areas is described the clock distribution networks of specific industrial circuits are surveyed and future trends are discussed.

Clock distribution networks in synchronous digital integrated circuits

Most electronic systems, whether self contained or embedded, have a predominant digital component consisting of a hardware platform which executes software application programs. Hardware/software co-design means meeting system level objectives by exploiting the synergism of hardware and software through their concurrent design. Co-design problems have different flavors according to the application domain, implementation technology and design methodology. Digital hardware design has increasingly more similarities to software design. Hardware circuits are often described using modeling or programming languages, and they are validated and implemented by executing software programs, which are sometimes conceived for the specific hardware design. Current integrated circuits can incorporate one (or more) processor core(s) and memory array(s) on a single substrate. These "systems on silicon" exhibit a sizable amount of embedded software, which provides flexibility for product evolution and differentiation purposes. Thus the design of these systems requires designers to be knowledgeable in both hardware and software domains to make good design tradeoffs. The paper introduces 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 develop a perspective on modern digital system design that relies on computer aided design (CAD) tools and methods.

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Hardware/software co-design

System-level design issues are gaining increasing attention, as behavioral synthesis tools and methodologies mature. We present the SpecSyn system-level design environment, which supports the new specify-explore-refine (SER) design paradigm. This three-step approach to design includes precise specification of system functionality, rapid exploration of numerous system-level design options, and refinement of the specification into one reflecting the chosen option. A system-level design option consists of an allocation of system components, such as standard and custom processors, memories, and buses, and a partitioning of functionality among those components. After refinement, the functionality assigned to each component can then he synthesized to hardware or compiled to software. We describe the issues and approaches for each part of the SpecSyn environment. The new paradigm and environment are expected to lead to a more than ten times reduction in design time, and our experiments support this expectation.

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SpecSyn: an environment supporting the specify-explore-refine paradigm for hardware/software system design

During system design, one or more portions of the system may be implemented with standard components that have a fixed pin structure and communication protocol. This paper described a new technique, interface process generation, for interfacing standard components that have incompatible protocols. Given an HDL description of the two protocols, we present a method to generate an interface process that allows the two protocols to communicate with each other.

Interfacing Incompatible Protocols Using Interface Process Generation

As methodologies and tools for chip-level design mature, design effort becomes focused on increasingly higher levels of abstraction. We present a methodology and tool for system-level specification, design and refinement that result in an executable specification for each system component. The specification for each component can then be synthesized into hardware or compiled to software. We highlight advantages of the proposed methodology compared to current practice. >

A system-design methodology: executable-specification refinement

Given a set of communication channels to be implemented as a single bus, the authors present a bus-generation algorithm which determines the width of a bus implementation. Tradeoffs between the width of the bus and the performance of the processes communicating over the bus are evaluated. The algorithm incorporates system level constraints such as data transfer rates and the number of pins and allows several channels that may be transferring different sizes of data to be implemented as a single bus. The authors demonstrate through a detailed example the usefulness of the algorithm in implementing system-level interfaces between modules. >

Sanjiv Narayan

Papers

Specification and Design of Embedded Systems

SpecSyn: an environment supporting the specify-explore-refine paradigm for hardware/software system design

Interfacing Incompatible Protocols Using Interface Process Generation

A system-design methodology: executable-specification refinement

Synthesis of system-level bus interfaces