【導(dǎo)讀】[摘要]本設(shè)計(jì)使用VHDL語言設(shè)計(jì)一個(gè)八路數(shù)字搶答器系統(tǒng)。VHDL是一種全方位的硬件描述語言，本文闡述了EDA的概念和發(fā)展、VHDL語言的優(yōu)點(diǎn)和語法結(jié)構(gòu)并分析講解了八路數(shù)字搶答器的各模塊的。功能要求、基本原理以及實(shí)現(xiàn)方法。早發(fā)現(xiàn)各子模塊及系統(tǒng)中的錯(cuò)誤，提高系統(tǒng)設(shè)計(jì)的效率。和鎖存功能；2.搶答成功聲音報(bào)警；；4.答題限時(shí)功能。EDA技術(shù)的設(shè)計(jì)優(yōu)勢················································1. 2系統(tǒng)方案的論證和選擇·········&#183

　　

【正文】 apter chip for the specific target pilation, mapping and programming logic to download and so on. EDA technologies, circuit design greatly improved the efficiency and operability, reduced the labor intensity. Now the concept or the category of EDA is widely used. Including machinery, electronics, munications, aerospace, chemical, mineral, biological, medical, military and other fields, have EDA applications. EDA technology has been present in large panies, enterprises and scientific research and teaching departments widely used. For example, in aircraft manufacturing process, from design, performance testing and characterization of up to flight simulation, may involve EDA technology. Electronic design automation (EDA) technology as the fast development of highperformance, highquality, high reliability electronic systems, an important platform and technical support, in 陜西理工學(xué)院畢業(yè)設(shè)計(jì) 第 22 頁 共 39 頁 fact, methodologies and EDA technology has been fully integrated into today39。s electronic product design and shape into, EDA technology has also started to engage in, including archiving, production, manufacture, testing links. Applications and the design objects based on different, EDA technology can also be broken down into system level design, chip design, board design and system design technology, and other machine process and methodology, as the industry pioneer and market leader in technology, Mentor Graphics Corporation39。s technologies and products cover a wide range of EDA field. IC design technology typically includes analog and custom IC design, mixedsignal SOC design, and ASIC design. Custom IC design is usually custom layout design, SPICE simulation, physical verification, parameter extraction and circuit simulation for the following important technical features。 mixedsignal SOC design mixedsignal mixedlanguage simulation technology for the important features。 ASIC design functional simulation, DFT (design for test), logic synthesis and prototyping for the important technical features。 At the same time ASIC and SOC design of highrisk, high cost and long development cycle makes prototyping technology is being increasingly popular. Boardlevel design techniques to programmable logic devices (PLD, FPGA, and SOPC) based on the design and PCB design, application and development of products to enhance the continuing high demand makes the integration of design, highspeed circuit signal integrity and EMI analysis and testing technology more and more popular, the construction of enterprise information technology needs of the engineering research and development platform has set new and higher challenges to business optimization library building ponents, electronic product design data management and standardization of enterprise archive to represent the design environment custom industrial applications has bee a highlight. Whole system design in recent years began to spread, car web design, embedded software development, macaroni systems modeling and simulation, and harness engineering design platform developed in the whole system has bee an important technology platform 3． PLC Introduction Programmable controller is the first in the late 1960s in the United States, then called Plc programmable logic controller (Programmable Logic Controller) is used to replace relays. For the implementation of the logical judgment, timing, sequence number, and other control functions. The concept is presented Plc General Motors Corporation. Plc and the basic design is the puter functional improvements, flexible, generic and other advantages and relay control system simple and easy to operate, such as the advantages of cheap prices bined controller hardware is standard and overall. According to the practical application of target software in order 陜西理工學(xué)院畢業(yè)設(shè)計(jì) 第 23 頁 共 39 頁 to control the content of the user procedures memory controller, the controller and connecting the accused convenient target. In the mid1970s, the Plc has been widely used as a central processing unit microprocessor, import export module and the external circuits are used, largescale integrated circuits even when the Plc is no longer the only logical (IC) judgment functions also have data processing, PID conditioning and data munications functions. International Electro technical Commission (IEC) standards promulgated programmable controller for programmable controller draft made the following definition: programmable controller is a digital electronic puters operating system, specifically for applications in the industrial design environment. It used programmable memory, used to implement logic in their internal storage operations, sequence control, timing, counting and arithmetic operations, such as operating instructions, and through digital and analog input and output, the control of various types of machinery or production processes. Programmable controller and related peripherals, and industrial control systems easily linked to form a whole, to expand its functional design. Programmable controller for the user, is a noncontact equipment, the procedures can be changed to change production processes. The programmable controller has bee a powerful tool for factory automation, widely popular replication. Programmable Logic Controllers (PLC), a puting device invented by Richard E. Morley in 1968, have been widely used in industry including manufacturing systems, transportation systems, chemical process facilities, and many others. At that time, the PLC replaced the hardwired logic with softwired logic or socalled relay ladder logic (RLL), a programming language visually resembling the hardwired logic, and reduced thereby the configuration time from 6 months down to 6 days Though PLC is widely used in industrial practice, the programming of PLC based control systems is still very much relying on trialanderror. Alike software engineering, PLC software design is facing the software dilemma or crisis in a similar way. Morley himself emphasized this aspect most forcefully by indicating If houses were built like software projects, a single woodpecker could destroy civilization.” Particularly, practical problems in PLC programming are to eliminate software bugs and to reduce the maintenance costs of old ladder logic programs. Though the hardware costs of PLC are dropping continuously, reducing