VHDL介绍及应用

90's in 20 centuries, international last electronics and calculator technique more the forerunner's nation, has been being actively investigating a new design method of the electronics electric circuit, and carried on an exhaustive change in the aspects of designing a method, tool wait, obtain huge success.At the design realm of the electronics technique, the application of programmable logic spare part(like CPLD, FPGA), have already got extensive universality, these spare parts brought tremendous vivid for the design of numerical system.These spare parts can pass a software plait a distance but as to it's hardware structure and work the way carry on heavy Gou and make thus the design of hardware can like software design so convenient fast.The all these biggest changed a traditional numerical method, design process of the system design and design idea and promoted the EDA technical quick development.

The EDA is an electronics design automation of abbreviation, design from the calculator assistance at the beginning of 90's in 20 centuries, calculator assistance manufacturing, calculator assistance test and calculator lend support to the concept of engineering a development since then.The EDA technique is to take calculator as tool, design at EDA software terrace up, use the hardware description language HDL completion a design a document, then is of oneself completed logic to edit and translate, turn Chien, partitioned by the calculator, comprehensive, excellent turn, set up, cloth line with imitate really, until for particular target chip of proper go together with to edit and translate, the logic reflect to shoot with plait distance download etc. work.The EDA technical emergence, biggest raised efficiency and maneuverability of electric circuit design, eased to design of labor strength.

These spare parts can pass a software plait a distance but as to it's hardware structure and work the way carry on heavy Gou and make thus the design of hardware can like software design so convenient fast.The all these biggest changed a traditional numerical method, design process of the system design and design idea and promoted the EDA technical quick development.Make 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 completion, and can design the electronics product is from the electric circuit, the function analyze compute of the whole process of design an IC landscape or PCB landscape on board auto processing completion.

Use to the EDA concept or category very breadth now.Include in each realm of the machine, electronics, correspondence, aviation aerospace, chemical engineering, mineral, living creature, medical science, military...etc., all there is EDA application.The EDA technique has already extensively used in each archduke department, the Qi business unit and research teaching section currently.For example in the airplane the manufacturing the process, from design, performance test and characteristic analytical until fly emulation, may involve an EDA technique.The EDA technique that this text point mainly to the design, 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 common use software and tool pile up one after another and get into an our country currently and have the EDA software of extensive infl

uence 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 net form a document with the third square software connect.

The VHDL birth in 1982.At the end of 1987, the VHDL is confirm by IEEE and American Ministry of National Defense to describe language for the standard hardware.Announced VHDL standard edition from the IEEE, IEEE-1076(call 87 versions) after, the each EDA company released own VHDL design environment one after another, or declared that the own design tool can connect with VHDL.Henceforth the VHDL designed realm to get to extensively accept in the electronics, and gradually replaced an originally not- standard hardware description language.In 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 edition.VHDL and Verilog are the industrial standard hardware description of the IEEEs language, again arrive support of numerous EDA companies, at electronics engineering realm, have become in general use hardware to describe language in fact.There 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 design.It expects to appear after the 80's of.BE at the beginning come 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 hardware.So it of the application mainly is an application in the design of numerical electric circuit.Currently, itis in the application most in china is thedesign which uses in the FPGA/CPLD/EPLD.Certainly 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 connect.In 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 language.VHDL procedure structure characteristics is an engineering design, or call that the design entity(can be a component, an electric circuit mold piece or a system) is divided into exterior(or call but part, and port) with inner part(or call to can't see part), since involve internal function and calculate way of entity to complete part of.At to 1 designed entity to define exterior interface after, once it internal development completion after, other designs can directly adjust to use this entity.This kind of will design 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 compare and the VHDL has a following characteristics:The function is strong and the design be vivid.The VHDL has the function strong language structure, can describe a complicated logic control with the simple and direct and explicit source code.It has a multi-la

yer design description function, in multiple layers thin turn, finally directly born electric circuit class description.The VHDL supports synchronous electric circuit, difference's tread electric circuit with random the design of electric circuit, this be the other hardware description although the language can't compare to.The 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 layer's turn a design again. Support extensively and be easy to a modification.Because the VHDL has already become IEEE standard the norm of hardware description language, most EDA tools almost support VHDL currently, this is VHDL of further expansion with extensively applied lay foundation.In the design process of the hardware electric circuit, the main design document is the source code which writes with the VHDL, the VHDL easily reads with the structure turn, so be easy to a modification design.

The strong system hardware describes ability.The VHDL has a multi-layer design description function, since can describe system class electric circuit, can describe door class electric circuit again.And description since can adopt a behavior description, deposit a machine to deliver description or structure description, can also adopt the hybrid description of threes mixture.Moreover, VHDL support is inertial to delay and deliver to delay, can also accurately build up hardware electric circuit model.VHDL support prepare definite of with from definition of data type, bring hardware description a bigger freedom degree, make design the personnel can expediently establish the system model of high time. The independence is at the design of spare part, have nothing to do with the craft.Don't need to consider a choice completion the spare part of design first while designing a personnel to carry on a design with the VHDL, can concentrate energy to carry on design of excellent turn.When the design description complete after, can carry out its function with various different spare part structure. Very strong transplantation ability.The VHDL is a kind of hardware description for standardize language, the same of design description can be support by the different tool and make to design to describe of the transplantation make possible.

Be easy to a share and reply to use.The VHDL adoption can build up various mold piece that can again make use of according to the design method of database.These canned in advance design or use to design a medium backup mold a piece before and depositted these to the database in, can be in laterly of the design carry on replying to use, can make the design result be design the personnel's to carry on exchanges and share, decrease hardware electric circuit design.

(1)compared with other hardware description languages, the VHDL have stronger behavior description ability, come to a decision him to become a system design realm the best hardware a description language thus.The strong behavior description ability is to avert from concrete spare part structure and describe and design important assurance of large-scale electronics system from the logic behavior.

(2)the VHDL be abundant of imitate true language sentence and database function, make in any big system of the design can inspect a function possibility of design the system in early days, can carry on imitating true emulation to the design at any time.

(3)the ability and procedure structure of the behavior description with lexical V

HDL come to a decision the decomposition that he has to support a large-scale design with have already have design of again make use of function.Meet the market demanding large-scale system efficiently, the completion of the high speed has to include many people the several generation hair set even together and abreast works and then can carry out.

(4)for use the design of an assurance of VHDL completion, can make use of EDA tool to carry on logic comprehensive with excellent turn, and auto of the VHDL describe the design change into the door class net form.

(5)the description of VHDL to design have opposite and independent, the design can not understand the structure of hardware and need not manage the target spare part that the end design carry out, either is what, but carry on an independent design.

Founded in 1981, this year has entered the Mentor of 25 years, is the oldest in the three major electronic design automation (EDA) vendors, and turnover ahead of a competitor four times, in addition to Mentor system design tools, market share, ranking first in the world, especially in the PCB layout, Mentor strengths which also ranked first in the world, its turnover is a full 1.5 times the second supplier. To assist customers in China \"audiovisual\" application-specific markets, \"Technical Support\" Mentor the largest part of human input (in the past each year is almost more than three times the rate of growth) in order to strengthen the ability of the Physical the Design and Functional Architecture ; and for the continued development of database management tool is also spared no effort in shipment volume growth of around 20% in the past five years, 15% of the revenue progress, is the fastest-growing EDA manufacturers.