内容案例介绍ldpe

Primitive:TransparentDataLatchwithAsynchronousPreset,GateEnable,andInvertedGate

Q

LDPE_1isatransparentdatalatchwithasynchronouspreset,gateenable,andinvertedgate.Whentheasynchronouspreset(PRE)isHigh,itoverridestheotherinputandpresetsthedata(Q)outputHigh.(Q)reflectsthedata(D)inputwhilethegate(G)and(PRE)areLowandgateenable(GE)isHigh.Thedataonthe(D)inputduringtheLow-to-Highgatetransitionisstoredinthelatch.Thedataonthe(Q)outputremainsunchangedaslongas(G)remainsHighor(GE)remainsLow.Thelatchisasynchronouslypreset,outputHigh,whenpowerisForSpartan-3Edevices,power-onconditionsaresimulatedwhenglobalset/reset(GSR)isactive.TheactiveleveloftheGSRdefaultstoactive-HighbutcanbeinvertedbyaddinganinverterinfrontoftheGSRinputoftheSTARTUP_SPARTAN3Esymbol.GDQ1XXX100XXNo010DD011XNo01DDThisdesignelementisinferredinthedesigncode;however,theelementcanbeinstantiatedforcaseswherestrictcementcontrol,relativecementcontrol,orinitializationattributesmustbeapplied.Allowed 0or0Specifiestheinitialvalueuponpower-uportheassertionofGSRforthe(Q)ForMoreConsulttheSpartan-3EDataSpartan-3ELibrariesGuideforSchematic ISE Spartan-3ELibrariesGuideforSchematicDesignsISE低密度聚乙烯LDPE_1是具有异步预设、门使能和反相门的透明数据锁存器。当异步预设(PRE)为时，它会覆盖其他输入并将数据(Q)输出预设为(Q)反映数据(D)输入，同时Q门(G)和(PRE)为低电平且门使能(GE)为高电PRE在门从低到高转换期间(D)输入上的数据在锁存器中。只要(G)保持或(Q)当通电时，锁存器被异步预设，输出对于Spartan-3E器件，当全局设置/复位(GSR)GSR的有效电平默认为有效，但可以通过在STARTUP_SPARTAN3E符号的GSR输入前面添加输入输出PREGEGD1.XXX00XX010011X01DDINIT010(Q)GSR置位时如需