数字逻辑设计及应用教学英文课件：Lec20-chap 8.ppt

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1、1DigitalLogicDesignandApplicationLecture#20Chapter8SequentialLogicDesignPracticesUESTC,Spring20132Chapter7SequentialLogicDesignPrinciplesCombinationallogiccircuitOutputs=f(currentinputs)SequentiallogiccircuitOutputs=f(currentinputs+entireinputhistory)storedinmemoryelementsLatchesandFlip-Flopsfe

2、edbacksequentialcircuitclockedsynchronousstatemachineMealymachineMooremachine虽然组合逻辑电路能够很好地处理像加、减等这样的操作，但是要单独使用组合逻辑电路，使操作按照一定的顺序执行，需要串联起许多组合逻辑电路，而要通过硬件实现这种电路代价是很大的，并且灵活性也很差。为了实现一种有效而且灵活的操作序列，需要构造一种能够存储各种操作之间的信息的电路→时序电路。时序电路可以提高器件利用效率。3Chapter7SequentialLogicDesignPrinciplesClocksignalclockperiod,cl

3、ockfrequency,clocktick,dutycycleBistableElementsMetastableCharacteristicLatchesS-RLatch,DLatchFlip-Flops,F/FEdge-Triggeredflip-flopMaster/Slaveflip-flopDFFTFFJ-KFFS-RFF4State-MachineStructureNextStateLogicFStateMemoryOutputLogicGinputsoutputsexcitationcurrentstateclocksignalexcitationequationtrans

4、itionequationoutputequation5State-MachineAnalysisDetermineexcitationequationforflip-flopcontrolinputsDetermineoutputequationfromthecircuitdiagramSubstitutetheexcitationequationsintotheflip-flopcharacteristicequationstoobtaintransitionequationsUsethetransitionequationsandoutputequationstoconstructa

5、transition/outputtableNamethestatesandobtainastate/outputtable(Optional)DrawastatediagramDescribethecircuitfunction6State-MachineDesignConstructstate/outputtable(orstatediagram)(optional)StateminimizationStateassignmentCreatetransition/outputtableDerivetransitionequationsandoutputequationsChooseaf

6、lip-floptypeforthestatememoryConstructexcitationequationsDrawalogiccircuitdiagram7State-MachineDesignStatetable→transitiontable→transitionequationStatediagram→transitionlist→transitionequationExcitationequation↑Stateassignment↓FFchoose↑K-map,∑(…),π(…)↑∑(…),π(…)Chapter7SequentialLogicDesignPrincipl

7、esSeveralimportantconceptionsBi-stable/LatchMeta-stableenableSynchronous/AsynchronousFinitestateLogicfunction89Chapter8SequentialLogicDesignPracticesSSILatchesandFlip-FlopsMSIDevice:Counters,ShiftRegistersOthers