【導(dǎo)讀】[摘要]傳統(tǒng)的交通燈控制系統(tǒng)多數(shù)由單片機(jī)或PLC實(shí)現(xiàn)，本文介紹的是基于EDA技術(shù)設(shè)計(jì)交通燈系統(tǒng)的一種方。通過(guò)對(duì)系統(tǒng)進(jìn)行結(jié)構(gòu)分析，采用了層次化的設(shè)計(jì)方法，給出了各個(gè)模塊的VHDL程序，利用Max+PlusⅡ?qū)?yīng)用程。序進(jìn)行了仿真，并給出了相應(yīng)的仿真結(jié)果。在用系統(tǒng)硬件描述語(yǔ)言進(jìn)行電路設(shè)計(jì)時(shí)，應(yīng)充分認(rèn)識(shí)到VHDL語(yǔ)言的特點(diǎn)，從設(shè)計(jì)思想、語(yǔ)句運(yùn)用及描述方法上等多方面對(duì)電路進(jìn)行優(yōu)化設(shè)計(jì)，并使用規(guī)模更小的可編程邏輯芯片，可以降低。城市交通是城市活動(dòng)的重要組成部分，猶如人體的動(dòng)脈，維系著整個(gè)城市的正常運(yùn)轉(zhuǎn)。汽車(chē)、地鐵、飛機(jī)等各種綜合型的運(yùn)輸方式。城市的歷史與文明、發(fā)展與興衰。飛速發(fā)展的同時(shí)也對(duì)交通設(shè)施的建設(shè)提出了更高的要求。以前普通的交通控制器能根據(jù)事先給定的時(shí)間進(jìn)行通道的通禁控制，以達(dá)到自動(dòng)控制的目的，因此，要求尋找一種可以隨時(shí)針對(duì)通道上車(chē)輛的密集程度來(lái)控制和調(diào)節(jié)主支干道的通禁時(shí)。間，從而減少不合理的堵車(chē)現(xiàn)象的發(fā)生。

　　

【正文】 n, eased to design of labor strength. These spare parts can pass a software plait a distance but as to it39。s hardware structure and work the way carry on heavy Gou and make thus the design of hardware can like software design so convenient all these biggest changed a traditional numerical method, design process of the system design and design idea and promoted the EDA technical quick use of EDA tool, the electronics designer can start design electronics system from the concept, calculate way, agreement...etc., a great deal of work can pass calculator pletion, and can design the electronics product is from the electric circuit, the function analyze pute of the whole process of design an IC landscape or PCB landscape on board auto processing pletion. Use to the EDA concept or category very breadth in each realm of the machine, electronics, correspondence, aviation aerospace, chemical engineering, mineral, living creature, medical science, military...etc., all there is EDA EDA technique has already extensively used in each archduke department, the Qi business unit and research teaching section example in the airplane the manufacturing the process, from design, performance test and characteristic analytical until fly emulation, may involve an EDA EDA technique that this text point mainly to the design, 畢業(yè)設(shè)計(jì) 第 24 頁(yè) 共 38 頁(yè) PCB design of the electronics electric circuit and IC design. The EDA design can is divided into system class, electric circuit class and physics to carry out class. The EDA in mon use software and tool pile up one after another and get into an our country currently and have the EDA software of extensive influence to have:MultiSIM 7(the latest edition of original EWB), PSPICE, OrCAD, PCAD, Protel, Viewlogic, Mentor, Graphics, Synopsys, LSIIogic, Cadence, MicroSim, ISE, modelsim etc..These tools all have stronger function, generally can used for a few aspects, for example a lot of softwares all can carry on an electric circuit design with imitate really, together entering can also carry on PCB to automatically set up cloth line, can output various form a document with the third square software connect. The VHDL birth in the end of 1987, the VHDL is confirm by IEEE and American Ministry of National Defense to describe language for the standard VHDL standard edition from the IEEE, IEEE1076(call 87 versions) after, the each EDA pany released own VHDL design environment one after another, or declared that the own design tool can connect with the VHDL designed realm to get to extensively accept in the electronics, and gradually replaced an originally not standard hardware description 1993, the IEEE carried on to revise to the VHDL, describe ability to up expand a VHDL contents from higher abstract layer and the system, announced the VHDL of new and Verilog are the industrial standard hardware description of the IEEEs language, again arrive support of numerous EDA panies, at electronics engineering realm, have bee in general use hardware to describe language in is expert think, in the new century in, the VHDL will start to undertake a greatly part of numerical system design mission at the Verilog language. The VHDL language is a kind of deluxe language which useds for an electric circuit expects to appear after the 8039。s at the beginning e out by American Ministry of National Defense development to provide the American solider with the credibility which uses to raise a design with cut 1 kind of development period to use the scope smaller design language. VHDL,Translating into chinese is soon extremely high the description language of the integrated circuit it of the application mainly is an application in the design of numerical electric , it is in the application most in china is the design which uses in the FPGA/CPLD/ in some units with stronger real strenght, it is also use to design ASIC. The VHDL mainly useds for the structure, behavior which describes numerical system, function with addition to implying many languages sentence which have a hardware characteristic, VHDL languages forms and description style and sentence construction are very similar at general calculator deluxe procedure structure characteristics is an engineering design, or call that the design entity(can be a ponent, an electric circuit mold piece or a system) is divided into exterior(or call but part, and port) with inner part(or call to can39。t see part), since involve internal function and calculate way of entity to plete part to 1 designed entity to define exterior interface after, once it internal development pletion after, other designs can directly adjust to use this kind of will design 畢業(yè)設(shè)計(jì) 第 25 頁(yè) 共 38 頁(yè) entity to be divided into a little bit basic VHDL system that is a VHDL system inside the concept of outside part design design of a little bit basic and other hardware describe the language pare and the VHDL has a following characteristics:The function is strong and the design be VHDL has the function strong language structure, can describe a plicated logic control with the simple and direct and explicit source has a multilayer design description function, in multiple layers thin turn, finally directly born electric circuit class VHDL supports synchronous electric circuit, difference39。s tread electric circuit with random the design of electric circuit, this be the other hardware description although the language can39。t pare VHDL still supports various design method, since support from the bottom upward design, support again from the design of crest declivity。Since the support mold piece turns a design, support layer39。s turn a design again. Support extensively and be easy to a the VHDL has already bee IEEE standard the norm of hardware description language, most EDA tools almost support VHDL currently, this is VHDL of further e