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This book is devoted to embedded systems (ESs), which can now be found in practically all fields of human activity. Embedded systems are essentially a special class of computing systems designed for monitoring and controlling objects of the physical world. The book begins by discussing the distinctive features of ESs, above all their cybernetic-physical character, and how they can be designed to deliver the required performance with a minimum amount of hardware. In turn, it presents a range of design methodologies. Considerable attention is paid to the hardware implementation of computational algorithms. It is shown that different parts of complex ESs could be implemented using models of finite state machines (FSMs). Also, field-programmable gate arrays (FPGAs) are very often used to implement different hardware accelerators in ESs. The book pays considerable attention to design methods for FPGA-based FSMs, before the closing section turns to programmable logic controllers widely used in industry. This book will be interesting and useful for students and postgraduates in the area of Computer Science, as well as for designers of embedded systems. In addition, it offers a good point of departure for creating embedded systems for various spheres of human activity.

The book is composed of two parts. The first part introduces the concepts of the design of digital systems using contemporary field-programmable gate arrays (FPGAs). Various design techniques are discussed and illustrated by examples. The operation and effectiveness of these techniques is demonstrated through experiments that use relatively cheap prototyping boards that are widely available. The book begins with easily understandable introductory sections, continues with commonly used digital circuits, and then gradually extends to more advanced topics. The advanced topics include novel techniques where parallelism is applied extensively. These techniques involve not only core reconfigurable logical elements, but also use embedded blocks such as memories and digital signal processing slices and interactions with general-purpose and application-specific computing systems. Fully synthesizable specifications are provided in a hardware-description language (VHDL) and are ready to be tested and incorporated in engineering designs. A number of practical applications are discussed from areas such as data processing and vector-based computations (e.g. Hamming weight counters/comparators). The second part of the book covers the more theoretical aspects of finite state machine synthesis with the main objective of reducing basic FPGA resources, minimizing delays and achieving greater optimization of circuits and systems.

The control unit is one of the most important parts of any digital system responsible for interplay of other system blocks. Very often, the model of a finite state machine (FSM) is used to represent the behaviour of a control unit. Modern computer-aided design tools include a lot of optimal solutions (library cells) for implementation of such regular blocks of digital systems as decoders, multiplexers, parallel multibit adders and so on. But as a rule, control units have an irregular structure which makes impossible to design their logic circuits using the standard library cells. To use these cells, an FSM can be represented by a multilevel model based on the principle of structural decomposition. In multilevel models, for example, multiplexers are used to replace logical conditions, decoders are used to implement microoperations, and different memory blocks are used to transform object codes. Design methods depend strongly on such factors as an FSM model in use, specific features of logic elements implementing its logic circuit, characteristics of a control algorithm to be interpreted. In the case of Moore FSM, optimization methods are based on existence of the classes of pseudoequivalent states. Their use permits to compress the transition table of Moore FSM till the size of the table for equivalent Mealy FSM. In the case of Mealy FSM, optimization methods are based on transformation of either object codes, or interpreted graph-schemes of algorithm. In the case of CPLD, the hardware decrease can be achieved using more than single source of state codes. In the case of FPGA, the structural decomposition allows using embedded memory blocks for implementation of decoding logic. In case of ASIC, design methods target on minimization of the chip area occupied by an FSM circuit. It can be achieved due to use of different encoding methods, where both internal states and collections of microoperations can be encoded. If a control algorithm is a linear one, thena state register of Moore FSM can be replaced by a counter. It leads to simplification of the input memory functions and, in turns, to the hardware amount decrease. The book includes a lot of design methods targeted on logic synthesis of both Mealy and Moore FSMs, where their logic circuits can be implemented using ASIC, as well as CPLD or FPGA. The most of discussed methods belong to the authors of this book. This book will be interesting and useful for students and postgraduates in the area of Computer Science, as well as for designers of digital systems included complex control units. Proposed models and design methods open new possibilities for creating logic circuits of control units with optimal hardware amount.

One of the very important parts of any digital system is the control unit, coordin- ing interplay of other system blocks. As a rule, control units have irregular str- ture, which makes process of their logic circuits design very sophisticated. In case of complex logic controllers, the problem of system design is reduced practically to the design of control units. Actually, we observe a real technical boom connected with achievements in semiconductor technology. One of these is the development of integrated circuit known as the'systems-on-a-programmable- chip'(SoPC), where the number of elements approaches one billion. Because of the extreme complexity of microchips, it is very important to develop effective design methods oriented on particular properties of logical elements. Solution of this problem permits impr- ing functional capabilities of the target digital system inside single SoPC chip. As majority of researches point out, design methods used in case of industrial packages are, in case of complex digital system design, far from optimal. Similar problems concern the design of control units with standard?eld-programmable logic devices (FPLD), such as PLA, PAL, GAL, CPLD, and FPGA. Let us point out that modern SoPC are based on CPLD or FPGA technology. Thus, the development of eff- tive design methods oriented on FPLD implementation of logic circuits used in the control units still remains the problem of great importance.