Design Recipes for FPGAs pot

[...]... 280 Summary 282 279 Chapter 27 Bibliography 283 Introduction 283 Useful texts for VHDL 283 Digital Systems Design 283 Designers Guide to VHDL 283 VHDL: Analysis and Modeling of Digital Systems VHDL for Logic Synthesis 284 Useful Texts for FPGAs 284 Design Warriors Guide to FPGAs 284 General Digital Design Books 284 Digital Design 284 Index 284 287 xv This page intentionally left blank Acknowledgements... Introduction Why FPGAs? There are numerous options for designers in selecting a hardware platform for custom electronics design, ranging from embedded processors, Application Specific Integrated Circuits (ASICs), Programmable Micro-processors (PICs), FPGAs to Programmable Logic Devices (PLDs) The decision to choose a specific technology such as an FPGA should depend primarily on the design requirements... integrated circuit design (Application Specific Integrated Circuits or ASICs) where each chip (ASIC) has to be designed, laid out, fabricated and packaged individually For large production runs this is cost effective, but obviously this approach is hugely expensive (masks alone for a current Silicon process may cost over $500 000) and time consuming (up to a year) Design Recipes for FPGAs From a software... today’s complex designs, we therefore rely on synthesis software to turn our VHDL design description into the logic functions that can be mapped onto the FPGA CLBs This design flow is an iterative process including optimization and implies a complete design flow This will be discussed in more detail later in this book Design constraints using FPGAs It is very easy to produce unrealistic designs using... level of optimization in the hardware design required For example, a simple software program can be written in C, and then a PIC device programmed, but the performance may be limited by the inability of the processor to offer parallel operation of key functions This can be implemented much more directly in an FPGA using parallelism and pipelining Design Recipes for FPGAs to achieve much greater throughput... Structure of CLBs 9 Design Recipes for FPGAs FPGA design techniques When we design using VHDL, these functions need to be mapped onto the low-level logic blocks on an FPGA In order to do this, we need to carry out three specific functions: 1 Mapping: Logic functions mapped onto CLBs 2 Placement: CLBs placed on FPGA 3 Routing: Routed connections between CLBs It is clearly impossible to design ‘by hand’... choosing a hardware platform is to identify both the design requirements and the hardware options, and then select a suitable platform based on those considerations For example, if the design requires a basic clock speed of up to 100 MHz then an FPGA would be a suitable platform If the clock speed could be 3–4 MHz, then the FPGA may be an expensive (overkill) option If the design requires a flexible... extensively in Printed Circuit Board (PCB) design and still are today, there has been a consistent effort over the last 20 years to introduce greater programmability into basic digital devices The reason for this need is the dichotomy resulting from the two differing design approaches used for most digital systems On the hardware side, the drive is usually toward ultimate performance: faster, smaller, lower... (FPGA), VHDL and the standard design flow In the second part of the book, a series of complex applications that encompass many of the key design problems facing designers today are worked through from start to finish in a practical way This will show how the designer can interpret a specification and develop a top-down design methodology and eventually build in detailed design blocks perhaps developed... make the reader able to develop practical, operational VHDL that will run correctly on FPGAs It is important to stress that his book is not designed as a language reference manual for VHDL There are plenty of those available and I have referenced them throughout the text This book is intended as a reference for design with VHDL and can be seen as complementary to a conventional VHDL textbook This .