Digitalization is an inevitable trend in the development of electronic design. EDA technology integrates computer technology and integrated circuits to continuously develop, bringing a new concept to the field of electronic design. In this paper, the author briefly introduces the concept of EDA technology, then elaborates on several typical characteristics of EDA technology, discusses the application and general process of EDA technology in electronic design, and finally starts from a careful attitude and based on experience. A few points of attention were raised.
0 Preface
The 21st century is an era of information. Various electronic technologies are rapidly developing at a rapid pace. Computers, mobile phones, and DVs have become an indispensable part of contemporary life. The functions of these electronic products are increasing and performance is getting better. The price has been reduced, and the reasons for this, the development of integrated circuit manufacturing technology and the improvement of electronic design technology are the two mainstream factors. The integrated circuit manufacturing technology is mainly micro-processing, and the electronic design technology is based on EDA technology. EDA technology has become one of the frontiers of the development of today's electronic technology. This is the result of the joint efforts of the more advanced countries. The application of CPLD and FPGA programmable logic devices has undoubtedly brought great design to electronic design. Flexibility and applicability.
1 Concepts and characteristics of EDA technology
1.1 Concept
EDA technology is the electronic design automation technology, which is developed by PLD technology. The application and integration scale of programmable logic device PLD brings great convenience and flexibility to the design of digital system, and changes the traditional digital. System design concepts, processes, methods. EDA technology emerged as the PLD technology continued to improve.
EDA technology is based on large-scale programmable devices, using computer as a tool, according to the hardware description language HDL to complete the expression, to achieve a new technology for the logic of compilation, segmentation, layout, optimization and other goals, with EDA technology, operation A software description can be used to implement a description of the hardware functions, and then the final design results can be obtained using FPGA/CPLD.
1.2 Features
1.2.1 New design method: top down
Traditional electronic design methods are generally "bottom-up". In general, after determining the standard general-purpose integrated circuit chip, the module design is completed and the system design is finally completed. This kind of design has long been insurmountable defects, low efficiency, easy to malfunction, too many components required, and high consumption... EDA technology is a breakthrough and transformation of traditional electronic design methods. Its design is "Top-down", that is, the system design is the entry point. At the time of design, the functional block diagram is divided and the structure of each part is planned. The simulation and error correction work is completed in the block diagram division stage, and HDL is also used. Complete the logical description of the high-level system. After verification, complete the electronic design with comprehensive optimization tools. With EDA technology, the operator can realize the description of the hardware function by using software, and then use FPGA/CPLD to get the final. Design results.
In this way, we can find that both simulation and debugging are completed at a high level in the early stage. This helps to detect errors that may occur in structural design and reduce errors in design work. The ground has improved the efficiency and success rate of electronic design work.
1.3 Unique Description Language: Hardware Description Language
EDA technology uses the hardware description language HDL as the main expression of system logic description, then what is the hardware description language? It is relative to general computer languages ​​such as C and Pascsl. It is mostly used to design hardware electronic systems. It is also a computer language. It describes the logic functions, circuit functions and connection methods of electronic systems. ABEL-HDL and VHDL are two widely described hardware description languages ​​today, and the latter are more widely used than the former.
ABEL can support input in various ways. The so-called input method refers to the expression of circuit system design, including truth table and state diagram. Its description has strong independence. At the same time, it can be described from wide aperture to system, so it can adapt to different scale programming design, and can also convert design environment by standard format design. Compared with VHDL, it The application surface is much wider, the operation is flexible and simple, the requirements are also loose, and it is easy to speed up.
1.4 Typical Design: ASIC
Nowadays, electronic products are updated very fast and the complexity is constantly improving. Sometimes a seemingly simple electronic system may be composed of tens of thousands of small and medium-sized integrated circuits, which makes electronic systems often suffer from high energy consumption and low reliability. The challenge of the problem. ASIC chips are an effective way to improve this problem.
It includes FPGA and CPLD devices. FPGA/CPLD is the basis for implementing EDA. It is also the final expression of EDA ideas. It is a high-density programmable logic device, which is generally like the development of samples or the development of small batches of products. Applicable, and greatly shorten the design cycle, cut costs, avoid risks, and enable products to be listed as soon as possible.
The structure of FPGAs and CPLDs is different. The former is a standard gate array, while the latter is an OR or array, but the integration and ease of use are similar, so they can go hand in hand. Of course, the two also have their own characteristics, the differences are reflected in the following aspects:
(1) The particle thickness is different. Compared with CPLD, FPGA particles are relatively thin, one of its particles is just a logical macro unit, and the CPLD is a logical macroblock.
(2) The applicable structure is different. FPGAs are more suitable for use in relatively rich structures of flip-flops. CPLDs are more suitable for applications where the flip-flop is limited but the product is particularly rich.
(3) Different programming methods. The FPGA can be programmed under the logic gate, and the method of changing the internal wiring is adopted, which has strong flexibility. GPLD can only be realized when the logic is fast, and the method of modifying the logic function of the already connected internal circuit is adopted, and the speed is faster.
(4) The function consumption is different. FPGA consumption is small and CPLD consumption is relatively large.
2 Application of EDA technology in electronic design
EDA technology belongs to a high-level electronic design method, which can also be called system-level design method. It is driven by concept. Electronic design workers do not need to use gate-level schematics, but only for the determined design goals. Realize the description of the circuit, so that the constraints and restrictions of the circuit details are reduced, so that the design can be more open and more creative. After the designer has the concept idea, then the high-level description input to the computer In the middle, the EDA system automatically completes the design of the entire electronics under rule-driven. In this way, the new concept can become a product in a period of time, and the electronic design process based on EDA technology is shown in Figure 1:
You can see the workflow of electronic EDA technology design: system partitioning, VHDL code or graphics input, code level function simulation, pre-delivery timing simulation, program download, ASIC implementation. The first step in electronic design is to present the design with text or graphical editing tools that implement the design description. The second step is to implement misalignment compilation by the compiler, that is, HDL program input. As for the input form, it is not necessary. The schematic diagram of the general design is relatively intuitive, so it is not difficult to master, and it is not difficult to be accepted, and the editor There are so many unit devices available, and this gives the designer the opportunity to choose the way to express it according to their needs. If the compiled file is a VHDL file, then an important task to be done before synthesis is The simulation is to send the original design program into the VHDL simulator. This simulation process can help to find out the errors that may occur in the structural design. The third step is to integrate, communicate software and hardware design. After synthesis, the netlist can be generated. For the netlist, functional simulation can be implemented to ensure that the design description strictly follows and conforms to the design intent. The simulation function is actually only from the logic function. Testing the electronic design does not involve some of the hardware aspects of the device, such as typical delay characteristics, and some less stringent designs. This layer of simulation can usually be eliminated. The final step is to download the program. After the simulation is confirmed to be correct, use FPGA/CPLD to complete the logic mapping operation, adapt, and finally use the JTAG programmer or other download design project to the target device PFGA to complete the system-level design.
3 Electronic design based on EDA technology should pay attention to matters
First, considering the uncertainty of the electronic circuit delay time, and partial auto-compilation may simplify two factors for redundant circuits. When applying EDA technology to electronic design, it is not appropriate to use an even number of inverses. The directors are connected in parallel to form a "delay circuit"; second, the input pins cannot be placed in a floating state, one must have an active signal to drive, and some unused pins must be momentarily Keep grounding; third, make sure that the power and ground pins of each device are always connected, and that filtering and decoupling are necessary between them; Fourth, it is easier and more convenient to make design extensions and modifications. In the process of using the device, there should be an extra amount in both the logic unit and the pin. Fifth, the environmental problem should also be vigilant to avoid overheating the device as much as possible.
In short, EDA technology is a breakthrough and innovation in traditional electronic design technology. If the support of EDA technology is lost, it is impossible to successfully complete the design and manufacture of large-scale integrated circuits. Conversely, the development needs of modern integrated circuit technology are EDA technology puts forward higher requirements, and it is foreseeable that in the near future, EDA technology will become the dominant force in electronic design.
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