计算结构poc报告_基于vhdl的poc设计

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1、TheReportofPOCDesignMarch29,20111、Purpose1.Thepurposeofthisprojectistodesignandsimulateaparalleloutputcontroller(POC)whichactsaninterfacebetweensystembusandprinter.2.TheuseofMaxPlusIIfordesignandsimulation.2、Taska.ThephysicalmodelofPOCPOCisoneofthemostcommonI/Omodules,namelyth

2、eparalleloutputcontroller.Itplaystheroleofaninterfacebetweenthecomputersystembusandtheperipheral(suchasaprinterorotheroutputdevices).Figure1PrinterConnectionFigure1showstheconnectingofaprintertothesystembusthroughthePOC.ThecommunicationbetweenPOCandtheprinteriscontrolledbya“ha

3、ndshake”protocolillustratedinFigure2.Figure2Thehandshake-timingdiagrambetweenPOCandtheprinterb.ThelogicalmodelofPOCThehandshakingprocessisdescribedasfollows:Whentheprinterisreadytoreceiveacharacter,itholdsRDY=1.ThePOCmustthenholdacharacteratPD(paralleldata)portandproduceapulse

4、attheterminalTR(transferrequest).TheprinterwillchangeRDYto0,takethecharacteratPDandholdtheRDYat0untilthecharacterhasbeenprinted(e.g.5or10ms),thensetRDY=1againwhenitisreadytoreceivethenextcharacter.(Supposetheprinterhasonlyaonecharacter“buffer”register,sothateachcharactermustbe

5、printedbeforethenextcharacterissent).Inordertoeaseyourdesignwork,thefurtherexplanationsofthePOCoperationsandsomedesignhintsaregivenasfollows:ThebufferregisterBRisusedtoholdacharacterthathasbeensentviathesystembuswhilethatthecharacterisbeingtransferredtotheprinter.Thestatusregi

6、sterSRisusedfortwocontrolfunctions:SR7servesasareadyflagforsystembustransferstoBR(liketheprinterRDYsignalfortransfersfromPOCtotheprinter),andSR0isusedtoenableordisableinterruptrequestsfromPOC.IfSR0=1,thenPOCwillinterruptwhenitisreadytoreceiveacharacter(i.e.,whenSR7=1).IfSR0=0,

7、thenPOCwillnotinterrupt.TheotherbitsofSRarenotusedandempty.ThetransferofacharactertoPOCviathesystembusproceedsasfollows.POCindicatesthatitisreadybysettingSR7.TheprocessorreadsSR(byexecutingapollingorinterruptserviceroutine)and,findingSR7=1,writesacharactertoBR.ThePOCclearsSR7w

8、henitloadsthischaracterintoBRtoindicatethatanothercharactersh