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1、Ch7???The?Interface?Technology?of?Single?Micro?ComputerlKeywords:接口(Interface)輸入/輸出(I/O,Input/Output)鍵盤(Keyboard)顯示器(Display)發(fā)光二極管(LED,LightEmittingDiode)液晶顯示器(LCD,LiquidCrystalDisplay)打印機(jī)(Printer)模數(shù)轉(zhuǎn)換器(A/DConverter,Analogy/DigitalConverter)數(shù)模轉(zhuǎn)換器(D/AConverter,
2、Digital/AnalogyConverter)lIntroduction:????TheInterfaceof8031composedofkeyboard,display,printer,A/Dconverter,D/Aconverterandsoon.????Theseperatekeyboardandthematrixkeyboardmakeupofthetwoformsofkeyboard.Figure1-TheseperatekeyboardFigure?2-The?4×4keymatrix??????
3、??Akeymatrixofsizem×ncontainsmrowsandncolumns.Thesekeysarelocatedatthem×nintersectingpointsofthematrix.????TheColumnandRowlinesareconnectedwiththeI/Olines.Soweneedm+nI/Olinestointerfacethiskeymatrix.?????TheLEDhaseightsegmentsfroma,b,c,d,e,f,g,dpandtwodigitpin
4、s---com.Figure?3-LED????Accordingtothemode,LEDdisplaycanbedevidedtostaticdisplayanddynamicdisplay.Figure?4-The?staticLEDdisplay????Figure?5-The?dynamicLEDdisplay????ThetipicalchipofA/DConverterisADC0809,whichisa8-BituPCompatibleA/DConverterswith8-Channel,ADC08
5、09dataacquisitioncomponentisamonolithicCMOSdevicewithan8-bitanalog-to-digitalconverter,8-channelmultiplexerandmicroprocessorcompatiblecontrollogic.The8-bitA/Dconverterusessuccessiveapproximationastheconversiontechnique.Theconverterfeaturesahighimpedancechopper
6、stabilizedcomparator,a256Rvoltagedividerwithanalogswitchtreeandasuccessiveapproximationregister.The8-channelmultiplexercandirectlyaccessanyof8-single-endedanalogsignals.Thedeviceeliminatestheneedforexternalzeroandfull-scaleadjustments.Easyinterfacingtomicropro
7、cessorsisprovidedbythelatchedanddecodedmultiplexeraddressinputsandlatchedTTLTRI-STATE.outputs.ThedesignoftheADC0808,ADC0809hasbeenoptimizedbyincorporatingthemostdesirableaspectsofseveralA/Dconversiontechniques.TheADC0808,ADC0809offershighspeed,highaccuracy,min
8、imaltemperaturedependence,excellentlong-termaccuracyandrepeatability,andconsumesminimalpower.Thesefeaturesmakethisdeviceideallysuitedtoapplicationsfromprocessandmachinecontroltocon