觸屏技術介紹

CapacitiveSensingTechnologyOverviewPSoC=ProgrammableSystemonChip

Features:Configurable

AnalogBlocksADCs,DACs,filters,amplifiers,comparators,modulatorsetc.

Configurable

DigitalBlocksTimers,Counters,PWMs,UART,SPI,SPI,I2C,IrDA,etc.4KBto32KBofFlashforcodestoreEmulateEEPROMinFlash256Bto2KBofSRAMfordatastoreM8CMicrocontrollerSamecoreusedinCypressUSBWhatIsPSoC?YouBuildtheDeviceYOUNeed!CapSense:TheoryCPissumofsensorpadcapacitanceandparasitics.CPishigherwhenfingerisonthesensorpad.ParasiticCapacitanceisgeneratedbycouplingfromthesensorpadtotraces,groundplane,andanysurroundingconductivematerial.DesignchallengeistofindasmallCF(0.1-2.0pF)inthepresenceofalargeCP(10-30pF)CPCPCfCfCSR:

CapSensewithRelaxationOscillator16-bitTimerVREFDataProcessingCXENOscillatorSW18-bitPWMENKeyConcept:

SwitchedCapacitor=AResistorV1V2IResistor:I=(V1-V2)/R (ifV1>V2)V1V2S1S2SwitchedCapacitor:Phase1:S1=CLOSED,S2=OPEN Q1=C*V1Phase2:S1=OPEN,S2=CLOSED Q2=C*V2?Q=Q1-Q2=C*V1-C*V2=C(V1-V2)I=?Q/?t-or-I=?Q*fswI=C(V1-V2)*fswRCResistor: I=(V1-V2)/RSwitchedCapacitor: I=C(V1-V2)*fswEquivalentResistor: (V1-V2)/R=C(V1-V2)*fsw 1/R=C*fsw R=1/C*fsw

Theequivalentresistanceof

eachsensorcanbecontrolled

bytheswitchingfrequencyKeyConcept:

SwitchedCapacitor=AResistorCSD:

OverviewofcircuitryCSD:

SwitchedcapacitorinputSensingswitchingcapacitorCxisChargedtothevoltagesourceVddatphasePhi1clocksignal;DischargedtothevoltageVcfiltatphasePhi2clocksignal;TheswitchingcapacitorisequivalenttoaresistorwithvalueRcCSD:

Delta-sigmamodulatorThesigma-deltamodulatorisformedbythecomparator,thecomparatorlatch,thestabilizingcapacitorCint,andthedischargeresistorRbCSD:

Delta-sigmamodulatorVoltageonthebuswithCintrisesdueswitchingcapcurrent.Whenthisvoltagereachesthecomparatorreferencevoltage,thecomparatortoggles

Bleedresistor,RB,startsdischargesbusviaswitchSW3.Whenthebusvoltagedropsbelowthereferencevoltage,thecomparatorswitchesagain,disablingfilterchargebleed;CSD:

Delta-sigmamodulatorThemodulatoroperatesasswitchingcapacitorcurrenttothedutycycleconverter;Thedutycycleislinearlyproportionaltothesensingcapacitancevalue:CSA:

CapSensewithSuccessiveApproximationCSA:

SuccessiveApproximationRoutine(Initialization)UseBinarySearchtodetermineiDACsettingnecessarytokeepvoltageonCMODatVREF.SuccessiveApproximation(SA)routineidentifiesiDACvaluethatyields~VREF.StoreiDACsettingforeachsensor(CX).CSA:

CapSensewithSuccessiveApproximationStage1CSA:

CapSensewithSuccessiveApproximationStage2Stage3isCPUprocessing!ButtonsandSlidingSwitchesSliderswitchisalineararrayofindependentswitchesCypressPSoCCapSenseCypressCapSensemarketentry–PCB-basedEmergingCapSenseMarket–GLASS/PETFilm-basedFPCFR4GlassFilmLCD-BasedDesignExamplesMulti-mediaDSCsHandsetsInformationKiosksPOSterminals….andmanymoreLCDfrontpaneldisplaysCapacitiveMatrixTouchPanelPrototypingboardandtestPCsoftwareapplicationCapSenseinCellPhonesNumericKeypadMenuNavigationQuickMenusCellPhoneWakeup―+VolumeControlBrightness

ContrastZoom―+ApplicationsforCapSenseKeymats

Example1–NavigationScrollwheelReplacecurrent‘joystick’ornavigationwheelwithCapSenseScrollwheelBenefits:

*Nomovingparts

*Configurableto

application

*Canbemadetobe

softwarecontext

dependantApplicationsforCapSenseKeymatsExample2–NavigationTouchpadBenefits:

*Easynavigation

*PCtouchpad‘feel’

*Customizefunction

byoverlaymaterialReplacecurrent‘joystick’ornavigationwheel-and-shortcutbuttonswithasmallTouchpadCustomizefunctionbyoverlaymaterial:OverlayExample1OverlayExample2OverlayExample3―+ReplacedomeswitcheswithlargeXYtouchpadApplicationsforCapSenseKeymats

Example3-FullXYTouchpadLargetouchpadenables:FullkeymatcursorcontrolSoftwarebuttonsScrollwheelemulationSlidersAnycombinationGesturerecognitionBenefits:

*Easynavigation

*Configurefunctionality

undersoftwarecontrolNEWUltraThinPackageOffering

3x3mm4x4mm5x5mm8x8mm1.0mm0.9mm0.6mmCY8C20434CY8C21434CY8C20334CY8C20234CY8C24794CY8C24894CY8C2499432QFN24QFN16QFN56QFN68QFN100uBGAIdealforconsumer

applicationsX/YZCapSenseNewProductUpdate

CY8C20x34(Quark)

CapSensededicatedPSoCdevice

KeyFeaturesLowerVDDforCapSensingoperation2.4V(Quark)vs.2.7V(Neutron)60%reductioninactivecurrent.25%reductioninsleepcurrentImprovednoiseimmunity(45times)Improvedsensitivity(300%greaterresolutionand30%fasterupdatespeeds)PackagingThinner(0.6mmvs.1.0mm)Smallerfootprints(3x3and4x4QFN–NEW) Moreintuitive,improvedcodedevelopmentwithCSABestPractices:StilluseseriesresistorsScheduleQuarkCSAUserModulefinalrelease:WW38MassProduction:WW44QuarksupportsLEDs,wirelessprotocolcontrol,mechanicalswitches,simpleLCD/LEDcontrol,batterymonitoring,andotherfunctions,simultaneouslywithCapSense!CapSenseNewProductUpdate

CY8C21x34(Neutron)

CapSensePLUSPSoCdevice

KeyFeaturesImprovednoiseimmunity,improvedSNRImprovedsensitivity

Moreintuitive,improvedcodedevelopmentwithCSDBestPractices:StilluseseriesresistorsMeetsallperformancespecificationsScheduleQuarkCSDUserModuleBetarelease:WW40QuarkCSDUserModuleFinalRelease:WW44SensingMethodUMreleasesMigratingfrom8C21Xto8C20XDesignConsiderationsHardwareSchematic:differentI/Omodesand10mAsinkcurrentModulationcapacitormayforcemovementofCapSenseI/OFewersupportedI/OmodesmayrequireschematicchangesFirmwareFewersupportedI/OmodesmayrequirefirmwarechangesAPIsaredifferentinCSA(moreintuitive)WizardinterfacehasNOTchanged(excludingbugfixes)fromCSRCalltoActionUseQuarkfordedicatedCapSensedesignsstartingWW39ContinuetouseNeutron/RadonforCapSensePLUS

PSoCFunctions21ButtonCapSenseModu