VHDL概述与基本结构.ppt

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1、第4章VHDL基础4.1VHDL概述1、什么是VHDL、有何优点2、怎样用VHDL描述数字电路3、学习VHDL应了解那些知识1、WhatisVHDLVeryhighspeedintegratedHardwareDescriptionLanguage(VHDL)isanindustrystandardhardwaredescriptionlanguagedescriptionthehardwareinlanguageinsteadofgraphiceasytomodifyeasytomaintai

2、nverygoodforcomplexcombinationallogicBCDto7Segmentconverteraddressdecodingstatemachinemorethanyouwant……..WhatVHDLStandardmeans?TheVHDLisusedtodescribeInputsportOutputsportbehaviorandfunctionsofthecircuitsThelanguageisdefinedbytwosuccessivestandardsIE

3、EEStd1076-1987(calledVHDL1987)IEEEStd1076-1993(calledVHDL1993)InputsportOutputportfunctionsAlteraVHDL（MaxPlusII综合器）AlteraMax+PlusIIsupportbothVHDL1987and1993Max+PlusIIonlysupportSUBSETofthetwoIEEEstandardDetailofthesupportcanbereferredtoAlteraMax+Plu

4、sIIVHDLhandbookonpage89Section3WhyIuseVHDLinsteadofGraphicEasytoModifyItismorepowerfulthanGraphicVHDLisaportablelanguagebecauseisdeviceindependentthesamecodecanbeappliedtoDevicemanufacturedbyCompanyAorCompanyBGraphicvsVHDLGraphiciswhatyoudrawiswhatyo

5、uget“tellmewhathardwareyouwantandIwillgiveittoyou”VHDLiswhatyouwriteiswhatfunctionalyouget“tellmehowyourcircuitshouldbehaveandtheVHDLcompilerwillgiveyouthehardwarethatdoesthejob”butthedesignercannotcontrolhowthecircuitimplementVHDLSynthesisvsotherHDL

6、sSynthesisVHDL“tellmehowyourcircuitshouldbehaveandIwillgiveyouhardwarethatdoesthejob”ABEL,PALASM,AHDL“tellmewhathardwareyouwantandIwillgiveittoyou”VHDL在电子系统设计中的应用电子系统的设计模块VHDL在电子系统设计中的应用电子系统设计的描述等级1、行为级2、RTL级（Registertransferlevel）3、逻辑门级4、版图级用VHDL可以描

7、述以上四个等级VHDL在电子系统设计中的应用系统设计的描述等级-行为级VHDL在电子系统设计中的应用系统设计的描述等级-RTL级VHDL在电子系统设计中的应用系统设计的描述等级-逻辑门级VHDL在电子系统设计中的应用系统设计的描述等级-制版级2、怎样用VHDL描述数字电路LIBRARYieee;USEieee.std_logic_1164.all;ENTITYmux21ISPORT(a,b:INSTD_LOGIC;S:INSTD_LOGICY:OUTSTD_LOGIC);ENDENTITYMUX

8、21;ARCHITECTUREbehavorOFmux21ISBEGINy<=aWHENs='0'ELSEb;ENDARCHITECTUREbehavor;IEEE库使用说明二选一数据选择器的端口说明实体内部逻辑关系说明结构体示例一二选一数据选择器（组合电路）ENTITYmux21ISPORT(a,b:INBIT;s:INBIT;y:OUTBIT);ENDENTITYmux21;ARCHITECTUREbehavorOFmux21ISBEGINy<=aWHENs='0'ELSEb;ENDARCH