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TCA8424www.
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comSCDS341–MARCH2013Low-Voltage8x16KeyboardScannerwithHIDoverI2CCompliantInterfaceCheckforSamples:TCA84241FEATURESOperatingPower-SupplyVoltageRangeofESDProtectionExceedsJESD221.
65Vto3.
6V–1000-VHuman-BodyModel(A114-A)SupportsFM+I2COperationupto1MHzCanSupportupto128(8x16)KeyScanRHB5mmx5mmRSM4mmx4mmInternalPower-On-ResetPREVIEWOpenDrainOpenDrainActiveLowINTOutputNoiseFilteronSCL/SDAandInputsOpenDrainOutputsCanSinkupto12mACurrentforLEDHardwareCodedHIDandREPORTDescriptorsAvailableWithPreprogrammedKeyboardMapSoftwareResetperHIDOverI2CStandardInternalPull-upResistorsMakeImplementationEasyWithnoNeedforExternalComponentsHIDOverI2CCommandsSupported–RESETRHA6mmx6mm–GETREPORT–SETREPORT–SETPOWERFixedLength8-byteINPUTReportcanDetectupto6SimultaneousKeyPressesExcludingModifiers(CTRL,ALT,SHIFT)INPUTReportGeneratedonKeyPressandReleaseLatch-UpPerformanceExceeds100mAPerJESD78,ClassIIDESCRIPTIONThis128keyscandeviceisspecificallytargetedtowardsendequipmentthatrunsonWindows8operatingsystem.
ThedeviceisfullycompliantwiththeHIDoverI2Cspecificationdefined(ver1.
0)definedbyMicrosoft.
TheHIDandreportdescriptorsarehardcodedintothedevicesothattheydon'tneedtobeprogrammedatproduction.
Thedevicealsocomeswithapreprogrammedkeyboardmapthatiscompatiblewithmoststandardlaptop/notebookkeyboards.
However,thedevicealsoavailablewithoutapre-programmedkeyboard,sothatanykeyboardmapmaybewrittenintoitatproduction.
ThedevicegeneratesINPUTreportsofstandard8-bytelengthwiththe1stbytebeingthemodifierbyte.
Afterthekeyboardmapisprogrammedintothedeviceitautomaticallyrecognizestherow/columnlocationofthemodifierkeysbasedontheirusagecode.
Itiscapableofdetectingandreportinguptosixsimultaneouskeypressespluseightmodifiers.
Itgeneratesaninputreportoneachkeypressandeachkeyrelease.
ThedevicealsosupportsLEDindicatorsthatarestandardonakeyboard.
Differentvariationssupport2,4or8LEDoutputs.
Eachoutputhasopendrainarchitectureandiscapableofsinkingupto12mAofcurrent.
TheLEDsarecontrolledbyastandardOUTPUTreportasdescribedintheHIDoverI2Cstandard.
1Pleasebeawarethatanimportantnoticeconcerningavailability,standardwarranty,anduseincriticalapplicationsofTexasInstrumentssemiconductorproductsanddisclaimerstheretoappearsattheendofthisdatasheet.
PRODUCTIONDATAinformationiscurrentasofpublicationdate.
Copyright2013,TexasInstrumentsIncorporatedProductsconformtospecificationsperthetermsoftheTexasInstrumentsstandardwarranty.
Productionprocessingdoesnotnecessarilyincludetestingofallparameters.
TCA8424SCDS341–MARCH2013www.
ti.
comThesedeviceshavelimitedbuilt-inESDprotection.
TheleadsshouldbeshortedtogetherorthedeviceplacedinconductivefoamduringstorageorhandlingtopreventelectrostaticdamagetotheMOSgates.
TOPTHROUGHVIEW2SubmitDocumentationFeedbackCopyright2013,TexasInstrumentsIncorporatedProductFolderLinks:TCA8424TCA8424www.
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comSCDS341–MARCH2013TOPTHROUGHVIEWPINFUNCTIONSNAMETYPEFUNCTIONSupplyvoltageforthedevice.
TheI2Cbusshouldbepulleduptothisrail.
ThekeymatrixIOvoltagesareVCCPoweralsoreferencedtothissupplyvoltage.
COL0–COL7InputCOLsofthekeymatrixROW0–ROW15OutputROWofkeymatrixLED0–LED7OutputOpendrainoutputfordrivingLEDsTESTInputHighvoltageinputusedtoprogramtheinternalmemory.
Tobegroundedinapplication.
(1)GNDPowerGroundINToutputActive-lowinterruptoutput.
ConnecttoVCCthroughapull-upresistor.
SCLInputSerialclockbus.
ConnecttoVCCthroughapull-upresistor.
SDAI/OSerialdatabus.
ConnecttoVCCthroughapull-upresistor.
(1)TESTpinmustbegroundedinapplicationtoensureproperoperationofdevice.
Copyright2013,TexasInstrumentsIncorporatedSubmitDocumentationFeedback3ProductFolderLinks:TCA8424TCA8424SCDS341–MARCH2013www.
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comSIMPLIFIEDBLOCKDIAGRAMI2CINTERFACEThebidirectionalI2Cbusconsistsoftheserialclock(SCL)andserialdata(SDA)lines.
BothlinesmustbeconnectedtoVCCthroughapull-upresistor.
Datatransfermaybeinitiatedonlywhenthebusisnotbusy.
I2CcommunicationwiththisdeviceisinitiatedbyamastersendingaStartcondition,ahigh-to-lowtransitionontheSDAinput/output,whiletheSCLinputishigh.
AftertheStartcondition,thedeviceaddressbyteissent,mostsignificantbit(MSB)first,includingthedatadirectionbit(R/W).
Afterreceivingthevalidaddressbyte,thisdevicerespondswithanacknowledge(ACK),alowontheSDAinput/outputduringthehighoftheACK-relatedclockpulse.
OntheI2Cbus,onlyonedatabitistransferredduringeachclockpulse.
ThedataontheSDAlinemustremainstableduringthehighpulseoftheclockperiod,aschangesinthedatalineatthistimeareinterpretedascontrolcommands(StartorStop).
AStopcondition,alow-to-hightransitionontheSDAinput/outputwhiletheSCLinputishigh,issentbythemaster.
AnynumberofdatabytescanbetransferredfromthetransmittertoreceiverbetweentheStartandtheStopconditions.
EachbyteofeightbitsisfollowedbyoneACKbit.
ThetransmittermustreleasetheSDAlinebeforethereceivercansendanACKbit.
ThedevicethatacknowledgesmustpulldowntheSDAlineduringtheACKclockpulse,sothattheSDAlineisstablelowduringthehighpulseoftheACK-relatedclockperiod.
Whenaslavereceiverisaddressed,itmustgenerateanACKaftereachbyteisreceived.
Similarly,themastermustgenerateanACKaftereachbytethatitreceivesfromtheslavetransmitter.
Setupandholdtimesmustbemettoensureproperoperation.
4SubmitDocumentationFeedbackCopyright2013,TexasInstrumentsIncorporatedProductFolderLinks:TCA8424TCA8424www.
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comSCDS341–MARCH2013Amasterreceiversignalsanendofdatatotheslavetransmitterbynotgeneratinganacknowledge(NACK)afterthelastbytehasbeenclockedoutoftheslave.
ThisisdonebythemasterreceiverbyholdingtheSDAlinehigh.
Inthisevent,thetransmittermustreleasethedatalinetoenablethemastertogenerateaStopcondition.
NOTEAnycommunicationtoanotherdeviceonthesameI2CBUSmustbeterminatedbyastopconditionbeforecommunicatingtotheTCA8424.
Anyglitchesbelow0.
7*VCContheSCLorSDAlineshouldbelessthan50nsaspertheI2Cspecification.
Figure1.
DefinitionofStartandStopConditionsFigure2.
BitTransferFigure3.
AcknowledgmentonI2CBusDEVICEI2CADDRESSTheaddressofthedeviceisshownbelow:Table1.
AddressReferenceSLAVEADDRESSI2CBUSSLAVEADDRESSB7B6B5B4B3B2B1B001110110(W)134(decimal),76(h)01110111(R)135(decimal),77(h)Copyright2013,TexasInstrumentsIncorporatedSubmitDocumentationFeedback5ProductFolderLinks:TCA8424TCA8424SCDS341–MARCH2013www.
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comThelastbitoftheslaveaddressdefinestheoperation(readorwrite)tobeperformed.
Ahigh(1)selectsareadoperation.
Whilealow(0)selectsawriteoperation.
OtherI2Caddressoptionsareavailable.
PleasecontactyourlocalTIsalespersonfordeviceswithalternateI2Caddress.
REGISTERADDRESSBYTEFollowingthesuccessfulacknowledgmentoftheI2Caddressbyte,thebusmastersendstworegisteraddressbytesindicatingtheaddressoftheregisteronwhichthereadorwriteoperationneedstobeperformed.
Thisregisteraddressisstoredinaninternalregisterandusedbythedeviceforsubsequentread/writetothedevice.
ThisisexplainedmoreindetailinsubsequentsectionsoftheDS.
OtherI2Caddressoptionsareavailable.
ContactyourlocalTIsalespersonfordeviceswithalternateI2Caddress.
Table2.
RegisterMapREGISTERADDRESSDESCRIPTIONPOWERUPDEFAULT(Hex)HIDdescriptor0000h-001DhHIDdescriptorSeesectiononHIDdescriptorReportDescriptor0030h-00F1hReportdescriptorSeesectiononReportdescriptorKeyboardMap0100h-01FFhkeyboardMapseesectiononKeyboardmapFunctionKeylocation(1)0201hFunctionKeylocationonKeyboardMap(2)0DefaultReportID0202hDefaultReportID1ReportID10203hReportID12ReportID20204hReportID23ReportID30205hReportID34ReportID40206hReportID45ReportID1usageIDs0207h-020EhUsageIDsassociatedwithReportID1A7–AEReportID2usageIDs020Fh-0216hUsageIDsassociatedwithReportID2AF–B6ReportID3usageIDs0217h-021EhUsageIDsassociatedwithReportID3B7–BAReportID4usageIDs021Fh-0226hUsageIDsassociatedwithReportID4BB–BE0400hinputreportlength(LSB)00h0401hinputreportlength(MSB)00h0402hReportIDA20403hmodifierbyte00h0404hreservedreservedInputreport0405husagecode100h0406husagecode200h0407husagecode300h0408husagecode400h0409husagecode500h040Ahusagecode600hOutputreport0500hLEDstatus00h0600hHIDoverI2CCommandlowbyte00hCommandregister0601hHIDoverI2CCommandhighbyte00hDataregister0700-070AhDataforHIDoverI2Ccommand00h(1)FunctionKeyUsageIDinkeyboardmapmustbenon-zero(2)Column/Rowintersectionoffunctionkey.
i.
e.
col3row4intersectionwouldread34h6SubmitDocumentationFeedbackCopyright2013,TexasInstrumentsIncorporatedProductFolderLinks:TCA8424TCA8424www.
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comSCDS341–MARCH2013Table2.
RegisterMap(continued)REGISTERADDRESSDESCRIPTIONPOWERUPDEFAULT(Hex)0000h(3)HIDDescriptorlength40h0001h41h0002hBCDversion42h0003h43h0004hReportdescriptorlength44h0005h45h0006hReportDescriptorRegisteraddress46h0007h47h0008hInputregisteraddress48h0009h49h000Ahmaxinputreportlength(including2bytes4Ahlengthfield)000Bh4Bh000ChOutputregisteraddress4Ch000Dh4Dh000Ehmaxoutputreportlength(including2bytes4EhHIDDescriptor(3)lengthfield)000Fh4Fh(0000h-001Dh)0010hCommandregisteraddress50h0011h51h0012hdataregisteraddress52h0013h53h0014hVendorID54h0015h55h0016hProductID56h0017h57h0018hVersionID58h0019h59h001AhReservedperHIDoverI2Cspecv0.
915Ah001Bh5Bh001Ch5Ch001Dh5Dh5Eh(3)TheHiddescriptorstartaddressmustbe0000hCopyright2013,TexasInstrumentsIncorporatedSubmitDocumentationFeedback7ProductFolderLinks:TCA8424TCA8424SCDS341–MARCH2013www.
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comHIDDESCRIPTORRETRIEVALFigure4.
TypicalRetrievaloftheHIDDescriptorFigure4showsthetypicalretrievaloftheHIDdescriptor.
ThisisthemostcommonwaytheHIDdescriptorisretrieved.
However,theTCA8424allowspartialretrievalofthedescriptorasdescribedintheHIDoverI2Cspecrev1.
0.
Table3.
ReportDescriptorRegisterAddressPowerupDefault305F3160326133623463356436653766386739683A693B6AReport(1)descriptor3C6B(0030h-00F1h)3D6C3E6D3F6E406F41704271437244734574467547764877(1)Reportdescriptorcontentsmayvarydependingonversionofdevice.
PleasecontactTIfordevicefordifferentReportDescriptorcontents8SubmitDocumentationFeedbackCopyright2013,TexasInstrumentsIncorporatedProductFolderLinks:TCA8424TCA8424www.
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comSCDS341–MARCH2013Table3.
ReportDescriptor(continued)RegisterAddressPowerupDefaultReportdescriptor4978(0030h-00F1h)4A794B7A4C7B4D7C4E7D4F7E507F5180528153825483558456855786588759885A895B8A5C8B5D8C5E8D5F8E608F6190629163926493659466956796689769986A996B9A6C9B6D9C6E9D6F9E709F71A072A173A274A375A476A5Copyright2013,TexasInstrumentsIncorporatedSubmitDocumentationFeedback9ProductFolderLinks:TCA8424TCA8424SCDS341–MARCH2013www.
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comTable3.
ReportDescriptor(continued)RegisterAddressPowerupDefaultReportdescriptor77A6(0030h-00F1h)78A779A87AA97BAA7CAB7DAC7EAD7FAE80AF81B082B183B284B385B486B587B688B789B88AB98BBA8CBB8DBC8EBD8FBE90BF91C092C193C294C395C496C597C698C799C89AC99BCA9CCB9DCC9ECD9FCEA0CFA1D0A2D1A3D2A4D3A5D410SubmitDocumentationFeedbackCopyright2013,TexasInstrumentsIncorporatedProductFolderLinks:TCA8424TCA8424www.
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comSCDS341–MARCH2013Table3.
ReportDescriptor(continued)RegisterAddressPowerupDefaultReportdescriptorA6D5(0030h-00F1h)A7D6A8D7A9D8AAD9ABDAACDBADDCAEDDAFDEB0DFB1E0B2E1B3E2B4E3B5E4B6E5B7E6B8E7B9E8BAE9BBEABCEBBDECBEEDBFEEC0EFC1F0C2F1C3F2C4F3C5F4C6F5C7F6C8F7C9F8CAF9CBFACCFBCDFCCEFDCFFED0FFD10D21D32D43Copyright2013,TexasInstrumentsIncorporatedSubmitDocumentationFeedback11ProductFolderLinks:TCA8424TCA8424SCDS341–MARCH2013www.
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comTable3.
ReportDescriptor(continued)RegisterAddressPowerupDefaultReportdescriptorD54(0030h-00F1h)D65D76D87D98DA9DB0ADC0BDD0CDE0DDF0EE00FE110E211E312E413E514E615E716E817E918EA19EB1AEC1BED1CEE1DEF1EF01FREPORTDESCRIPTORRETREIVAL12SubmitDocumentationFeedbackCopyright2013,TexasInstrumentsIncorporatedProductFolderLinks:TCA8424TCA8424www.
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comSCDS341–MARCH2013INPUTREPORTInputreportsareusedtocommunicatekeypressesandreleasestothehostcontroller.
TheTCA8424iscapableofcommunicatinguptosixsimultaneouskeypressesanduptoeightmodifierkeys.
ThestandardmodifierkeysrecognizedbytheTCA8424are(UsageIDbasedonHIDusagetablesver1.
11).
TheusageIDforeachkeyisstoredinthekeyboardmapsectionofNVmemory.
LeftCtrl(UsageID–E0)Leftshift(UsageID–E1)LeftAlt(UsageID–E2)LeftGUI(UsageID–E3)RightCtrl(UsageID–E4)Rightshift(UsageID–E5)RightAlt(UsageID–E6)RightGUI(UsageID–E7)Belowisthatformatofastandardinputreport.
Thefirsttwobytesaredatalengthfieldindicatingthelengthofinputreport.
ByteBit7Bit6Bit5Bit4Bit3Bit2Bit1Bit00000010111000000002ReportID3RightGUIRightAltRightShiftRightCtrlLeftGUILeftAltLeftShiftLeftCtrl4Reserved5Key1UsageID6Key2UsageID7Key3UsageID8Key4UsageID9Key5UsageID10Key6UsageIDAninputreportisgeneratedforeverykeypressandalsooneverykeyrelease.
IfnokeysarepressedafterakeyreleasethenthereportcontainsallzeroesexceptfortheDatalengthfield(firsttwobytes)andtheReportID.
Inputreportsarealsogeneratedifonlymodifierkeysarepressed(notaccompaniedbyanyotherkey).
Thedatalengthfield(firsttwobytes)forastandardkeypressisalways11.
SPECIALMODIFIER(Fnkey)ANDALTERNATEREPORTIDsOtherthanthestandardmodifiers,theTCA8424alsosupportsonespecialmodifiersuchasthefunction(FN)key.
Thisoperatesdifferentfromtheothermodifierkeysinthat,itisnotrepresentedinthemodifierbyteoftheinputreport.
TheTCA8424onlysupportsasinglekeypressincombinationwiththeFNkey.
WhentheFNkeyispressedtheTCA8424generatesadefaultinputreportindicatingthatallkeyshavebeenreleased.
AFNkeyreleasewillgenerateaninputreportwiththecurrentReportIDandclearedusagecodes.
TheTCA8424onlysupportsasinglekeypressincombinationwiththeFNkey.
AnykeypressedaftertheFNkeythatdoesnothaveanon-zeroUsageIDwillbeignored.
OncetheFNkeyispressedandakeythathasanUsageIDinthealternatekeyboardmaphasbeenpressed,additionalkeypresseswillbeignoreduntileithertheFNkeyisreleasedorthesecondkeythathadanUsageIDinthealternatekeyboardmapisreleased.
Inadditiontostandardfunctionkeys,manykeyboardssupportspecialfunctionssuchasvolumeup,volumedown,skiptrack,previoustracketc.
ReportIDsareusedasawayforthehostprocessortoidentifywhethertheusageIDcorrespondstoastandardfunctionkeyoraspecialfunctionkey.
TheTCA8424supportsFivedifferentreportIDs.
ReportIDsmustbenon-zero.
1.
DefaultReportID–locatedataddress0202h.
ThisIDispopulatedintheinputreportwhenthereisanormalkeypressoraregularfunctionkey.
2.
ReportID1–locatedataddress0203h.
ThisIDispopulatedinthereportwhentheUsageIDofthekeypressdetectedbytheTCA8424correspondstoausageIDlocatedinthememoryrange(0207h-020Eh)3.
ReportID2–locatedataddress0204h.
ThisIDispopulatedinthereportwhentheUsageIDofthekeyCopyright2013,TexasInstrumentsIncorporatedSubmitDocumentationFeedback13ProductFolderLinks:TCA8424TCA8424SCDS341–MARCH2013www.
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compressdetectedbytheTCA8424correspondstoausageIDlocatedinthememoryrange(020Fh-0216h)4.
ReportID3–locatedataddress0204h.
ThisIDispopulatedinthereportwhentheUsageIDofthekeypressdetectedbytheTCA8424correspondstoausageIDlocatedinthememoryrange(0217h-021Eh)5.
ReportID4–locatedataddress0204h.
ThisIDispopulatedinthereportwhentheUsageIDofthekeypressdetectedbytheTCA8424correspondstoausageIDlocatedinthememoryrange(021Fh-0226h)Ascanbeinferredfromtheabovedescription,wheneverakeypressisdetected,theTCA8424looksuptheusageIDfromthealternatekeyboardmapandthencomparesthisusageIDwiththeusageIDscorrespondingtoReportID1,ReportID2,ReportID3,andReportID4.
Ifthereisamatch,thencorrespondingreportIDispopulatedinthespecialinputreport.
IfnotthedefaultinputreportisusedwiththedefaultReportID.
(1)Belowistheformatofthespecialinputreport.
Theformatissimilartothebitfieldrepresentationusedtorepresentthemodifierbyteinthestandardinputreport.
UsageIDbytelocation0willcorrespondtothefirstUsageIDinmemoryfortherespectiveReportID(2)anddescendwithUsageIDbytelocation7correspondingtothelastUsageIDinmemory.
(2)Table4.
SpecialInputReportByteBit7Bit6Bit5Bit4Bit3Bit2Bit1Bit00000001001000000002ReportIDUsageIDUsageIDUsageIDUsageIDUsageIDUsageIDUsageIDUsageID3bytelocationbytelocationbytelocationbytelocationbytelocationbytelocation2bytelocation1bytelocation765430(1)Thelast5keyUsageIDsintheinputreportandthemodifierbytewillalwaysread00hwhenthefunctionkeyispressedinadditiontoanotherkey.
(2)ForReportID1:UsageIDbytelocation0correspondstomemorylocation0207h.
UsageIDbytelocation7correspondstomemorylocation020Eh.
Figure5.
InputReportRetrievalItisimportanttonotethat,unlikeretrievalofotherreports,wherethefirstI2Ctransactionisawrite,inthecaseofinputreportthefirsttransactionitselfisareadoperationasindicatedbyBit8oftheI2Caddress.
14SubmitDocumentationFeedbackCopyright2013,TexasInstrumentsIncorporatedProductFolderLinks:TCA8424TCA8424www.
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comSCDS341–MARCH2013OUTPUTREPORTOutputreportsareusedbythehosttoturnON/OFFanyindicatorLEDs(capslock,numlocketc.
)onthekeyboard.
TheTCA8424cansupportfrom2to4LEDindicatorsdependingontheversionofthedevicechosen.
Theoutputreportsaresinglebytereports(8-bit)whereeachbitindicatesthestatusofthecorrespondingLED.
A'1'indicatesthattheLEDisturnedonwhereasa'0'turnsofftheLED.
Belowistheformatoftheoutputreportreceivedfromthehost.
Justasinthecaseoftheinputreportthefirsttwobytesindicatethelengthoftheoutputreport.
ByteBit7Bit6Bit5Bit4Bit3Bit2Bit1Bit00000000111000000002ReservedReservedReservedReservedLED3LED2LED1LED0Figure6.
OutputReportRetrievalCOMMANDandDATAREGISTERTheHIDoverI2Cspecrequiresthatalldevicesrespondtocertaincommands.
Thecommandsareissuedtothecommandregister.
ThecommandisanopcodeasdefinedbytheHIDoverI2Cspec.
Theoperandforthecommandgoestothedataregister.
BelowisalistofcommandssupportedbytheTCA8424.
OpCodeCommandNameEffectonDeviceDeviceisresetandallregistersarereturnedtodefaultvalue.
Thiscommandhasthesameeffectonthe0001bRESETdeviceasapoweronreset.
0010bGET_REPORTMostrecentinputreportistransferredtoDataRegister0011bSET_REPORTDataregistercontentsareusedtoturnon/offLED.
1000bSET_POWERAllLEDsareturnedoffanddeviceisinlowestcurrentmode(willstilldetectkeypresses)TheI2CtransactionsusedtoissuethesecommandsareexactlyasdescribedintheHIDoverI2Cstandard.
RESETAfterreceivingtheRESETcommand,thedevicewillgothroughafullpoweronresetandallregistersareloadedwiththeirdefaultvalues.
TheTCA8424takes~600storesetandduringthistimeallI2Ctrafficwillbeignoredbythedevice.
Aftercomingoutofreset,thedatalengthfieldintheinputreportispopulatedwith0000handtheINTsignalisasserted.
GET_REPORTTheGET_REPORTcommandwillretrievethecurrentinputreportfromthedevicebutwillnotcleartheinterruptassertedfromakeypressorrelease.
Copyright2013,TexasInstrumentsIncorporatedSubmitDocumentationFeedback15ProductFolderLinks:TCA8424TCA8424SCDS341–MARCH2013www.
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comSET_REPORTTheSET_REPORTcommandisusedtosetthecontentsoftheoutputreport.
TheDatashallbepackagedwiththelengthfieldas0x0003,andthethirdbyteshalldescribetheLEDoutputsasdefinedinthereportdescriptor.
SET_POWERTheSET_POWER=SLEEPcommandwillturnoffalltheLEDoutputsandcleartheinputreportincludingreportIDandlengthfield.
IfakeyispressedwhenSET_POWER=SLEEPcommandisreceived,keyscanwillstopwhenthecommandisreceived.
TCA8424willwaitforallkeystobereleasedbeforeanysubsequentkeypresswillassertaninterrupt.
IfakeyispressedandnotreleasedwhiledeviceisasleepandtheSET_POWER=WAKEcommandisreceived,thekeyscannerwillstartandassertaninterruptthatakeyhasbeenpressed.
TheSET_POWER=WAKEcommandisreceivedtheLEDoutputswillbereturnedtothestatetheywerebeforetheSET_POWER=SLEEPwasreceived.
Ifacommandtochangetheoutputreportisreceivedduringsleep,theLEDstatuswillindicatethatofthelastoutputreportreceiveduponSET_POWER=WAKE.
Ifkeysarepressedwhilethedeviceisenteringsleepmode,areadoftheinputreportoruseoftheGET_REPORTcommandbeforeallkeysarereleased,maynotreflectthecurrentstateofthekeyboard.
AnykeypressesthathappenafterallkeysarereleasedwillpopulatetheinputreportandassertINT.
KEYBOARDMAPTheNonvolatilememorycontainsasectionthatcontainsthekeyboardmap.
Eachbytelocationinthekeyboardmap,ismappedtoaspecificrowcolumnintersectiononthekeymatrix,andcontainstheusageIDofthekeylocatedinthatrowcolumnintersection.
Thekeyboardmapconsistsoftwosections.
Eachrowcolumnintersectionismappedtoonelocationineachsection.
TheprimarysectioncontainstheusageIDofthekeyandthealternatesectioncontainsthealternateusageIDofthekeythatwillbereportedwhenthespecialmodifier(FN)isused.
Onlykeyswithnon-zerousagecodeswillberecognized,includingthefunctionkey.
Thedeviceisavailablewithsomepredefinedkeyboardmaps.
Itisalsoavailablewiththekeyboardmapnotprogrammedsothattheendusermayprogramthekeyboardmapbasedonthekeyboardbeingused.
AlternatelyyoumaycontactTIforcustomvariationsofthepartwithdifferentkeyboardmapsprogrammedbyspecialrequest.
Thetablebelowillustratesthecolumn-rowintersectionsandthememorylocationstheyaremappedto.
KEYBOARDMAP(PRIMARY)KEYBOARDMAP(SECONDARY)C0C1C2C3C4C5C6C7C0C1C2C3C4C5C6C7R0A1B1C1D1E1F18191R0A1B1C1D1E1F18191R1A2B2C2D2E2F28292R1A2B2C2D2E2F28292R2A3B3C3D3E3F38393R2A3B3C3D3E3F38393R3A4B4C4D4E4F48494R3A4B4C4D4E4F48494R4A5B5C5D5E5F58595R4A5B5C5D5E5F58595R5A6B6C6D6E6F68696R5A6B6C6D6E6F68696R6A7B7C7D7E7F78797R6A7B7C7D7E7F78797R7A8B8C8D8E8F88898R7A8B8C8D8E8F88898R8A9B9C9D9E9F98999R8A9B9C9D9E9F98999R9AABACADAEAFA8A9AR9AABACADAEAFA8A9AR10ABBBCBDBEBFB8B9BR10ABBBCBDBEBFB8B9BR11ACBCCCDCECFC8C9CR11ACBCCCDCECFC8C9CR12ADBDCDDDEDFD8D9DR12ADBDCDDDEDFD8D9DR13AEBECEDEEEFE8E9ER13AEBECEDEEEFE8E9ER14AFBFCFDFEFFF8F9FR14AFBFCFDFEFFF8F9FR15B0C0D0E0F08090A0R15B0C0D0E0F08090A016SubmitDocumentationFeedbackCopyright2013,TexasInstrumentsIncorporatedProductFolderLinks:TCA8424TCA8424www.
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comSCDS341–MARCH2013KEYSCANLOGICFunctionalOverviewUponpoweruporwhencomingoutofRESET,thedevicesinitializesitselfwithalltheregistershavingthepowerupdefaultvalue.
AlltheCOLxpinsarepulleduptoVCCbyinternalpullupresistors.
AlltheROWxpinsarepulledlow.
Thedeviceisnowinidle/standbymode(lowestpowerstate).
Whenanykeyispressed,oneoftheCOLpinsgetsconnectedtooneoftheROWpins,therebypullingdownthecorrespondingCOLpin.
Thisinitiatesthekeyscan.
Whenthisoccurstheinternaloscillatorturnson,andeachROWxpingoeslow,oneaftertheother,forapproximately800uSwhiletheCOLxinputsaresampledateachstep.
Then,foreverykeythatispressed,thecorrespondingusageIDfromthekeyboardmapisregistered.
Afterapproximately25mS,thescanwillrepeat.
Ifanypreviouslypressedkeyisstillpressed,thenthecorrespondingcodeiswrittentotheInputregister.
Thescancontinuestorepeataslongastherearekeyspressed.
Now,whenapreviouslypressedkeyisreleasedanotherinputreportisgeneratedwiththekeysthatarestillpressed,orifnokeysarepressed,thenaninputreportwithallzeroUsagecodesisreported.
Oncetheinputreporthasbeenpopulatedintotheinputregister,theINTisassertedtoindicatetothehostthataninputreportisnowavailable.
Interrupt(INT)OutputAninterruptisgeneratedwhenthedevicehasaninputreportreadyfortheHOSTtoread.
ResettingtheinterruptisachievedbyreadingtheINPUTRegister.
UsingtheGET_REPORTcommandwillnotcleartheinterrupt.
Theinterruptwillclearafterthe2ndreadbyteoftheemptyinputreportonreset.
Afterreset,adefaultinputreportreadwillcleartheinputreportafterthelastbyteisread.
Ifaspecialinputreportisread,theinterruptclearsafterthe4thbyteisread.
Theinterruptstatusisupdatedinthereadmodeattheacknowledge(ACK)ornotacknowledge(NACK)bitfollowingtherisingedgeoftheSCLsignalafterthelastbyteoftheinputreporthasbeenread.
TheINPUTregisterwillkeepgettingupdatedwiththemostrecentkeypressreportsevenwhiletheINTsignalstaysasserted.
InorderavoidmissingofkeypressesitisrecommendedthathostprocessorrespondtointerruptservicerequestinVCC±10mASDAVO=0±30mAContinuousoutputlowIOLINTVO=0±10mAcurrentLEDxVO=0±20mATstgStoragetemperaturerange–65150°C(1)Stressesbeyondthoselistedunder"absolutemaximumratings"maycausepermanentdamagetothedevice.
Thesearestressratingsonly,andfunctionaloperationofthedeviceattheseoranyotherconditionsbeyondthoseindicatedunder"recommendedoperatingconditions"isnotimplied.
Exposuretoabsolute-maximum-ratedconditionsforextendedperiodsmayaffectdevicereliability.
(2)Theinputnegative-voltageandoutputvoltageratingsmaybeexceedediftheinputandoutputcurrentratingsareobserved.
Copyright2013,TexasInstrumentsIncorporatedSubmitDocumentationFeedback19ProductFolderLinks:TCA8424TCA8424SCDS341–MARCH2013www.
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comRECOMMENDEDOPERATINGCONDITIONSoveroperatingfree-airtemperaturerange(unlessotherwisenoted)MINMAXUNITVCCISupplyvoltage1.
653.
6VVtestVoltageontestpinDuringnormaloperation(inapplication)GNDGNDVVILEDVoltageonLEDoutput5VVIHHigh-levelinputvoltageSCL,SDA0.
7*VCCI3.
6VVILLow-levelinputvoltageSCL,SDA–0.
30.
3*VCCIVSDA20mALow-leveloutputIOLINT3mAcurrentLEDx12mATAOperatingfree-airtemperature–4085°CELECTRICALCHARACTERISTICSAllvaluesarespecifiedat25°Coperatingtemperature(unlessotherwisenoted)PARAMETERTESTCONDITIONSVCCMINTYPMAXUNITVIKInputdiodeclampvoltageII=–18mA1.
65Vto3.
6V–1.
2V1.
65V0.
41.
8V0.
4ROWx,INTIOL=3mA2.
5V0.
4V3.
3V0.
43.
6V0.
4VOL1.
65V0.
41.
8V0.
4SDAIOL=20mA2.
5V0.
4V3.
3V0.
43.
6V0.
41.
8V0.
4VVOLLEDxIOL=12mA3.
3V0.
45V0.
4IOLLEDxVOL=0.
4V1.
65V–5.
5V12mARintInternalpullupresistance80100120k1.
65V0.
2581.
8V0.
278Iccsh0CurrentconsumptionFscl=0kHz,oscillatoroff2.
5V0.
412A3.
3V0.
54163.
6V0.
6201.
65V17181.
8V1820Icc4khz1CurrentconsumptionFscl=400kHz,oscillatoron2.
5V2530A3.
3V33403.
6V39501.
65V36401.
8V3950Icc1Mhz1CurrentconsumptionFscl=1MHz,oscillatoron2.
5V4860A3.
3V65703.
6V6080ΔIccIncrementalcurrentfordurationofkeypressOnekeypressed1.
65V–3.
6V3945ACinSCL,SDA510pF20SubmitDocumentationFeedbackCopyright2013,TexasInstrumentsIncorporatedProductFolderLinks:TCA8424TCA8424www.
ti.
comSCDS341–MARCH2013I2CINTERFACETIMINGREQUIREMENTSoveroperatingfree-airtemperaturerange(unlessotherwisenoted)STANDARDFASTMODEFASTMODEMODEPLUS(FM+)I2CBUSPARAMETERUNITI2CBUSI2CBUSMINMAXMINMAXMINMAXfsclI2Cclockfrequency0100040001000kHztschI2Cclockhightime40.
60.
26μstsclI2Cclocklowtime4.
71.
30.
5μstspI2Cspiketime505050nstsdsI2Cserialdatasetuptime25010050nstsdhI2Cserialdataholdtime000nsticrI2Cinputrisetime100020300120ns20x(VDD/20x(VDD/ticfI2Cinputfalltime300300120ns5.
5V)5.
5V)20x(VDD/20x(VDD/tocfI2Coutputfalltime;10pFto400pFbus300300120μs5.
5V)5.
5V)tbufI2CbusfreetimebetweenStopandStart4.
71.
30.
5μststsI2CStartorrepeaterStartconditionsetuptime4.
70.
60.
26μststhI2CStartorrepeaterStartconditionholdtime40.
60.
26μstspsI2CStopconditionsetuptime40.
60.
26μstvd(data)Validdatatime;SCLlowtoSDAoutputvalid3.
450.
30.
90.
45μsValiddatatimeofACKcondition;ACKsignalfromSCLtvd(ack)3.
450.
30.
90.
45μslowtoSDA(out)lowSWITCHINGCHARACTERISTICSoveroperatingfree-airtemperaturerange(unlessotherwisenoted)PARAMETERFROM(INPUT)TO(OUTPUT)MINMAXUNITtirInterruptresetdelaytimeSCLINT600nstpvOutputdatavalidSCLLEDx155nsCopyright2013,TexasInstrumentsIncorporatedSubmitDocumentationFeedback21ProductFolderLinks:TCA8424TCA8424SCDS341–MARCH2013www.
ti.
comPARAMETERMEASUREMENTINFORMATIONA.
CLincludesprobeandjigcapacitance.
tocfismeasuredwithCLof10pFor400pF.
Allinputsaresuppliedbygeneratorshavingthefollowingcharacteristics:PRR≤10MHz,ZO=50,tr/tf≤30ns.
Allparametersandwaveformsarenotapplicabletoalldevices.
Figure11.
I2CInterfaceLoadCircuitandVoltageWaveformsA.
CLincludesprobeandjigcapacitance.
Allinputsaresuppliedbygeneratorshavingthefollowingcharacteristics:PRR≤10MHz,ZO=50,tr/tf≤30ns.
Allparametersandwaveformsarenotapplicabletoalldevices.
Figure12.
InterruptLoadCircuitandVoltageWaveforms22SubmitDocumentationFeedbackCopyright2013,TexasInstrumentsIncorporatedProductFolderLinks:TCA8424TCA8424www.
ti.
comSCDS341–MARCH2013PARAMETERMEASUREMENTINFORMATION(continued)Figure13.
LEDLoadConfigurationFigure14.
RowPull-downLoadConfigurationCLincludesprobeandjigcapacitance.
tpvismeasuredfrom0.
7*VCConSCLto50%I/O(Pn)output.
Allinputsaresuppliedbygeneratorshavingthefollowingcharacteristics:PRR≤10MHz,ZO=50,tr/tf≤30ns.
Theoutputsaremeasuredoneatatime,withonetransitionpermeasurement.
Allparametersandwaveformsarenotapplicabletoalldevices.
Copyright2013,TexasInstrumentsIncorporatedSubmitDocumentationFeedback23ProductFolderLinks:TCA8424PACKAGEOPTIONADDENDUMwww.
ti.
com10-Dec-2020Addendum-Page1PACKAGINGINFORMATIONOrderableDeviceStatus(1)PackageTypePackageDrawingPinsPackageQtyEcoPlan(2)Leadfinish/Ballmaterial(6)MSLPeakTemp(3)OpTemp(°C)DeviceMarking(4/5)SamplesTCA8424RHARNRNDVQFNRHA402500RoHS&GreenNIPDAULevel-3-260C-168HR-40to85PZ424(1)Themarketingstatusvaluesaredefinedasfollows:ACTIVE:Productdevicerecommendedfornewdesigns.
LIFEBUY:TIhasannouncedthatthedevicewillbediscontinued,andalifetime-buyperiodisineffect.
NRND:Notrecommendedfornewdesigns.
Deviceisinproductiontosupportexistingcustomers,butTIdoesnotrecommendusingthispartinanewdesign.
PREVIEW:Devicehasbeenannouncedbutisnotinproduction.
Samplesmayormaynotbeavailable.
OBSOLETE:TIhasdiscontinuedtheproductionofthedevice.
(2)RoHS:TIdefines"RoHS"tomeansemiconductorproductsthatarecompliantwiththecurrentEURoHSrequirementsforall10RoHSsubstances,includingtherequirementthatRoHSsubstancedonotexceed0.
1%byweightinhomogeneousmaterials.
Wheredesignedtobesolderedathightemperatures,"RoHS"productsaresuitableforuseinspecifiedlead-freeprocesses.
TImayreferencethesetypesofproductsas"Pb-Free".
RoHSExempt:TIdefines"RoHSExempt"tomeanproductsthatcontainleadbutarecompliantwithEURoHSpursuanttoaspecificEURoHSexemption.
Green:TIdefines"Green"tomeanthecontentofChlorine(Cl)andBromine(Br)basedflameretardantsmeetJS709Blowhalogenrequirementsof<=1000ppmthreshold.
Antimonytrioxidebasedflameretardantsmustalsomeetthe<=1000ppmthresholdrequirement.
(3)MSL,PeakTemp.
-TheMoistureSensitivityLevelratingaccordingtotheJEDECindustrystandardclassifications,andpeaksoldertemperature.
(4)Theremaybeadditionalmarking,whichrelatestothelogo,thelottracecodeinformation,ortheenvironmentalcategoryonthedevice.
(5)MultipleDeviceMarkingswillbeinsideparentheses.
OnlyoneDeviceMarkingcontainedinparenthesesandseparatedbya"~"willappearonadevice.
IfalineisindentedthenitisacontinuationofthepreviouslineandthetwocombinedrepresenttheentireDeviceMarkingforthatdevice.
(6)Leadfinish/Ballmaterial-OrderableDevicesmayhavemultiplematerialfinishoptions.
Finishoptionsareseparatedbyaverticalruledline.
Leadfinish/Ballmaterialvaluesmaywraptotwolinesifthefinishvalueexceedsthemaximumcolumnwidth.
ImportantInformationandDisclaimer:TheinformationprovidedonthispagerepresentsTI'sknowledgeandbeliefasofthedatethatitisprovided.
TIbasesitsknowledgeandbeliefoninformationprovidedbythirdparties,andmakesnorepresentationorwarrantyastotheaccuracyofsuchinformation.
Effortsareunderwaytobetterintegrateinformationfromthirdparties.
TIhastakenandcontinuestotakereasonablestepstoproviderepresentativeandaccurateinformationbutmaynothaveconducteddestructivetestingorchemicalanalysisonincomingmaterialsandchemicals.
TIandTIsuppliersconsidercertaininformationtobeproprietary,andthusCASnumbersandotherlimitedinformationmaynotbeavailableforrelease.
InnoeventshallTI'sliabilityarisingoutofsuchinformationexceedthetotalpurchasepriceoftheTIpart(s)atissueinthisdocumentsoldbyTItoCustomeronanannualbasis.
TAPEANDREELINFORMATION*AlldimensionsarenominalDevicePackageTypePackageDrawingPinsSPQReelDiameter(mm)ReelWidthW1(mm)A0(mm)B0(mm)K0(mm)P1(mm)W(mm)Pin1QuadrantTCA8424RHARVQFNRHA402500330.
016.
46.
36.
31.
112.
016.
0Q2PACKAGEMATERIALSINFORMATIONwww.
ti.
com29-Sep-2019PackMaterials-Page1*AlldimensionsarenominalDevicePackageTypePackageDrawingPinsSPQLength(mm)Width(mm)Height(mm)TCA8424RHARVQFNRHA402500367.
0367.
038.
0PACKAGEMATERIALSINFORMATIONwww.
ti.
com29-Sep-2019PackMaterials-Page2www.
ti.
comGENERICPACKAGEVIEWThisimageisarepresentationofthepackagefamily,actualpackagemayvary.
Refertotheproductdatasheetforpackagedetails.
VQFN-1mmmaxheightRHA40PLASTICQUADFLATPACK-NOLEAD6x6,0.
5mmpitch4225870/Awww.
ti.
comPACKAGEOUTLINE6.
155.
856.
155.
851.
00.
80.
050.
002X4.
536X0.
52X4.
540X0.
50.
340X0.
300.
182.
620.
13.
520.
1(0.
1)TYPVQFN-1mmmaxheightRHA0040EPLASTICQUADFLATPACK-NOLEAD4219054/A04/20200.
08C0.
1CAB0.
05NOTES:1.
Alllineardimensionsareinmillimeters.
Anydimensionsinparenthesisareforreferenceonly.
DimensioningandtolerancingperASMEY14.
5M.
2.
Thisdrawingissubjecttochangewithoutnotice.
3.
Thepackagethermalpadmustbesolderedtotheprintedcircuitboardforthermalandmechanicalperformance.
PIN1INDEXAREASEATINGPLANEPIN1IDSYMMEXPOSEDTHERMALPADSYMM11011202130314041SCALE2.
000ABCwww.
ti.
comEXAMPLEBOARDLAYOUT36X(0.
5)(R0.
05)TYP0.
07MAXALLAROUND0.
07MINALLAROUND40X(0.
6)40X(0.
24)(5.
8)(5.
8)(2.
62)(3.
52)(0.
2)TYPVIA(0.
6)TYP(0.
91)(1.
06)VQFN-1mmmaxheightRHA0040EPLASTICQUADFLATPACK-NOLEAD4219054/A04/2020NOTES:(continued)4.
Thispackageisdesignedtobesolderedtoathermalpadontheboard.
Formoreinformation,seeTexasInstrumentsliteraturenumberSLUA271(www.
ti.
com/lit/slua271).
5.
Viasareoptionaldependingonapplication,refertodevicedatasheet.
Ifanyviasareimplemented,refertotheirlocationsshownonthisview.
Itisrecommendedthatviasunderpastebefilled,pluggedortented.
SYMMSYMMLANDPATTERNEXAMPLEEXPOSEDMETALSHOWNSCALE:15XSEESOLDERMASKDETAIL11011202130314041METALEDGESOLDERMASKOPENINGEXPOSEDMETALMETALUNDERSOLDERMASKSOLDERMASKOPENINGEXPOSEDMETALNONSOLDERMASKDEFINED(PREFERRED)SOLDERMASKDEFINEDSOLDERMASKDETAILSwww.
ti.
comEXAMPLESTENCILDESIGN40X(0.
6)40X(0.
24)36X(0.
5)(5.
8)(5.
8)6X(1.
15)6X(1)(R0.
05)TYP(0.
675)(1.
2)VQFN-1mmmaxheightRHA0040EPLASTICQUADFLATPACK-NOLEAD4219054/A04/2020NOTES:(continued)6.
Lasercuttingapertureswithtrapezoidalwallsandroundedcornersmayofferbetterpasterelease.
IPC-7525mayhavealternatedesignrecommendations.
SOLDERPASTEEXAMPLEBASEDON0.
125MMTHICKSTENCILSCALE:15XEXPOSEDPAD4175%PRINTEDSOLDERCOVERAGEBYAREAUNDERPACKAGESYMMSYMM11011202130314041IMPORTANTNOTICEANDDISCLAIMERTIPROVIDESTECHNICALANDRELIABILITYDATA(INCLUDINGDATASHEETS),DESIGNRESOURCES(INCLUDINGREFERENCEDESIGNS),APPLICATIONOROTHERDESIGNADVICE,WEBTOOLS,SAFETYINFORMATION,ANDOTHERRESOURCES"ASIS"ANDWITHALLFAULTS,ANDDISCLAIMSALLWARRANTIES,EXPRESSANDIMPLIED,INCLUDINGWITHOUTLIMITATIONANYIMPLIEDWARRANTIESOFMERCHANTABILITY,FITNESSFORAPARTICULARPURPOSEORNON-INFRINGEMENTOFTHIRDPARTYINTELLECTUALPROPERTYRIGHTS.
TheseresourcesareintendedforskilleddevelopersdesigningwithTIproducts.
Youaresolelyresponsiblefor(1)selectingtheappropriateTIproductsforyourapplication,(2)designing,validatingandtestingyourapplication,and(3)ensuringyourapplicationmeetsapplicablestandards,andanyothersafety,security,orotherrequirements.
Theseresourcesaresubjecttochangewithoutnotice.
TIgrantsyoupermissiontousetheseresourcesonlyfordevelopmentofanapplicationthatusestheTIproductsdescribedintheresource.
Otherreproductionanddisplayoftheseresourcesisprohibited.
NolicenseisgrantedtoanyotherTIintellectualpropertyrightortoanythirdpartyintellectualpropertyright.
TIdisclaimsresponsibilityfor,andyouwillfullyindemnifyTIanditsrepresentativesagainst,anyclaims,damages,costs,losses,andliabilitiesarisingoutofyouruseoftheseresources.
TI'sproductsareprovidedsubjecttoTI'sTermsofSale(https:www.
ti.
com/legal/termsofsale.
html)orotherapplicabletermsavailableeitheronti.
comorprovidedinconjunctionwithsuchTIproducts.
TI'sprovisionoftheseresourcesdoesnotexpandorotherwisealterTI'sapplicablewarrantiesorwarrantydisclaimersforTIproducts.
IMPORTANTNOTICEMailingAddress:TexasInstruments,PostOfficeBox655303,Dallas,Texas75265Copyright2021,TexasInstrumentsIncorporated
ti.
comSCDS341–MARCH2013Low-Voltage8x16KeyboardScannerwithHIDoverI2CCompliantInterfaceCheckforSamples:TCA84241FEATURESOperatingPower-SupplyVoltageRangeofESDProtectionExceedsJESD221.
65Vto3.
6V–1000-VHuman-BodyModel(A114-A)SupportsFM+I2COperationupto1MHzCanSupportupto128(8x16)KeyScanRHB5mmx5mmRSM4mmx4mmInternalPower-On-ResetPREVIEWOpenDrainOpenDrainActiveLowINTOutputNoiseFilteronSCL/SDAandInputsOpenDrainOutputsCanSinkupto12mACurrentforLEDHardwareCodedHIDandREPORTDescriptorsAvailableWithPreprogrammedKeyboardMapSoftwareResetperHIDOverI2CStandardInternalPull-upResistorsMakeImplementationEasyWithnoNeedforExternalComponentsHIDOverI2CCommandsSupported–RESETRHA6mmx6mm–GETREPORT–SETREPORT–SETPOWERFixedLength8-byteINPUTReportcanDetectupto6SimultaneousKeyPressesExcludingModifiers(CTRL,ALT,SHIFT)INPUTReportGeneratedonKeyPressandReleaseLatch-UpPerformanceExceeds100mAPerJESD78,ClassIIDESCRIPTIONThis128keyscandeviceisspecificallytargetedtowardsendequipmentthatrunsonWindows8operatingsystem.
ThedeviceisfullycompliantwiththeHIDoverI2Cspecificationdefined(ver1.
0)definedbyMicrosoft.
TheHIDandreportdescriptorsarehardcodedintothedevicesothattheydon'tneedtobeprogrammedatproduction.
Thedevicealsocomeswithapreprogrammedkeyboardmapthatiscompatiblewithmoststandardlaptop/notebookkeyboards.
However,thedevicealsoavailablewithoutapre-programmedkeyboard,sothatanykeyboardmapmaybewrittenintoitatproduction.
ThedevicegeneratesINPUTreportsofstandard8-bytelengthwiththe1stbytebeingthemodifierbyte.
Afterthekeyboardmapisprogrammedintothedeviceitautomaticallyrecognizestherow/columnlocationofthemodifierkeysbasedontheirusagecode.
Itiscapableofdetectingandreportinguptosixsimultaneouskeypressespluseightmodifiers.
Itgeneratesaninputreportoneachkeypressandeachkeyrelease.
ThedevicealsosupportsLEDindicatorsthatarestandardonakeyboard.
Differentvariationssupport2,4or8LEDoutputs.
Eachoutputhasopendrainarchitectureandiscapableofsinkingupto12mAofcurrent.
TheLEDsarecontrolledbyastandardOUTPUTreportasdescribedintheHIDoverI2Cstandard.
1Pleasebeawarethatanimportantnoticeconcerningavailability,standardwarranty,anduseincriticalapplicationsofTexasInstrumentssemiconductorproductsanddisclaimerstheretoappearsattheendofthisdatasheet.
PRODUCTIONDATAinformationiscurrentasofpublicationdate.
Copyright2013,TexasInstrumentsIncorporatedProductsconformtospecificationsperthetermsoftheTexasInstrumentsstandardwarranty.
Productionprocessingdoesnotnecessarilyincludetestingofallparameters.
TCA8424SCDS341–MARCH2013www.
ti.
comThesedeviceshavelimitedbuilt-inESDprotection.
TheleadsshouldbeshortedtogetherorthedeviceplacedinconductivefoamduringstorageorhandlingtopreventelectrostaticdamagetotheMOSgates.
TOPTHROUGHVIEW2SubmitDocumentationFeedbackCopyright2013,TexasInstrumentsIncorporatedProductFolderLinks:TCA8424TCA8424www.
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comSCDS341–MARCH2013TOPTHROUGHVIEWPINFUNCTIONSNAMETYPEFUNCTIONSupplyvoltageforthedevice.
TheI2Cbusshouldbepulleduptothisrail.
ThekeymatrixIOvoltagesareVCCPoweralsoreferencedtothissupplyvoltage.
COL0–COL7InputCOLsofthekeymatrixROW0–ROW15OutputROWofkeymatrixLED0–LED7OutputOpendrainoutputfordrivingLEDsTESTInputHighvoltageinputusedtoprogramtheinternalmemory.
Tobegroundedinapplication.
(1)GNDPowerGroundINToutputActive-lowinterruptoutput.
ConnecttoVCCthroughapull-upresistor.
SCLInputSerialclockbus.
ConnecttoVCCthroughapull-upresistor.
SDAI/OSerialdatabus.
ConnecttoVCCthroughapull-upresistor.
(1)TESTpinmustbegroundedinapplicationtoensureproperoperationofdevice.
Copyright2013,TexasInstrumentsIncorporatedSubmitDocumentationFeedback3ProductFolderLinks:TCA8424TCA8424SCDS341–MARCH2013www.
ti.
comSIMPLIFIEDBLOCKDIAGRAMI2CINTERFACEThebidirectionalI2Cbusconsistsoftheserialclock(SCL)andserialdata(SDA)lines.
BothlinesmustbeconnectedtoVCCthroughapull-upresistor.
Datatransfermaybeinitiatedonlywhenthebusisnotbusy.
I2CcommunicationwiththisdeviceisinitiatedbyamastersendingaStartcondition,ahigh-to-lowtransitionontheSDAinput/output,whiletheSCLinputishigh.
AftertheStartcondition,thedeviceaddressbyteissent,mostsignificantbit(MSB)first,includingthedatadirectionbit(R/W).
Afterreceivingthevalidaddressbyte,thisdevicerespondswithanacknowledge(ACK),alowontheSDAinput/outputduringthehighoftheACK-relatedclockpulse.
OntheI2Cbus,onlyonedatabitistransferredduringeachclockpulse.
ThedataontheSDAlinemustremainstableduringthehighpulseoftheclockperiod,aschangesinthedatalineatthistimeareinterpretedascontrolcommands(StartorStop).
AStopcondition,alow-to-hightransitionontheSDAinput/outputwhiletheSCLinputishigh,issentbythemaster.
AnynumberofdatabytescanbetransferredfromthetransmittertoreceiverbetweentheStartandtheStopconditions.
EachbyteofeightbitsisfollowedbyoneACKbit.
ThetransmittermustreleasetheSDAlinebeforethereceivercansendanACKbit.
ThedevicethatacknowledgesmustpulldowntheSDAlineduringtheACKclockpulse,sothattheSDAlineisstablelowduringthehighpulseoftheACK-relatedclockperiod.
Whenaslavereceiverisaddressed,itmustgenerateanACKaftereachbyteisreceived.
Similarly,themastermustgenerateanACKaftereachbytethatitreceivesfromtheslavetransmitter.
Setupandholdtimesmustbemettoensureproperoperation.
4SubmitDocumentationFeedbackCopyright2013,TexasInstrumentsIncorporatedProductFolderLinks:TCA8424TCA8424www.
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comSCDS341–MARCH2013Amasterreceiversignalsanendofdatatotheslavetransmitterbynotgeneratinganacknowledge(NACK)afterthelastbytehasbeenclockedoutoftheslave.
ThisisdonebythemasterreceiverbyholdingtheSDAlinehigh.
Inthisevent,thetransmittermustreleasethedatalinetoenablethemastertogenerateaStopcondition.
NOTEAnycommunicationtoanotherdeviceonthesameI2CBUSmustbeterminatedbyastopconditionbeforecommunicatingtotheTCA8424.
Anyglitchesbelow0.
7*VCContheSCLorSDAlineshouldbelessthan50nsaspertheI2Cspecification.
Figure1.
DefinitionofStartandStopConditionsFigure2.
BitTransferFigure3.
AcknowledgmentonI2CBusDEVICEI2CADDRESSTheaddressofthedeviceisshownbelow:Table1.
AddressReferenceSLAVEADDRESSI2CBUSSLAVEADDRESSB7B6B5B4B3B2B1B001110110(W)134(decimal),76(h)01110111(R)135(decimal),77(h)Copyright2013,TexasInstrumentsIncorporatedSubmitDocumentationFeedback5ProductFolderLinks:TCA8424TCA8424SCDS341–MARCH2013www.
ti.
comThelastbitoftheslaveaddressdefinestheoperation(readorwrite)tobeperformed.
Ahigh(1)selectsareadoperation.
Whilealow(0)selectsawriteoperation.
OtherI2Caddressoptionsareavailable.
PleasecontactyourlocalTIsalespersonfordeviceswithalternateI2Caddress.
REGISTERADDRESSBYTEFollowingthesuccessfulacknowledgmentoftheI2Caddressbyte,thebusmastersendstworegisteraddressbytesindicatingtheaddressoftheregisteronwhichthereadorwriteoperationneedstobeperformed.
Thisregisteraddressisstoredinaninternalregisterandusedbythedeviceforsubsequentread/writetothedevice.
ThisisexplainedmoreindetailinsubsequentsectionsoftheDS.
OtherI2Caddressoptionsareavailable.
ContactyourlocalTIsalespersonfordeviceswithalternateI2Caddress.
Table2.
RegisterMapREGISTERADDRESSDESCRIPTIONPOWERUPDEFAULT(Hex)HIDdescriptor0000h-001DhHIDdescriptorSeesectiononHIDdescriptorReportDescriptor0030h-00F1hReportdescriptorSeesectiononReportdescriptorKeyboardMap0100h-01FFhkeyboardMapseesectiononKeyboardmapFunctionKeylocation(1)0201hFunctionKeylocationonKeyboardMap(2)0DefaultReportID0202hDefaultReportID1ReportID10203hReportID12ReportID20204hReportID23ReportID30205hReportID34ReportID40206hReportID45ReportID1usageIDs0207h-020EhUsageIDsassociatedwithReportID1A7–AEReportID2usageIDs020Fh-0216hUsageIDsassociatedwithReportID2AF–B6ReportID3usageIDs0217h-021EhUsageIDsassociatedwithReportID3B7–BAReportID4usageIDs021Fh-0226hUsageIDsassociatedwithReportID4BB–BE0400hinputreportlength(LSB)00h0401hinputreportlength(MSB)00h0402hReportIDA20403hmodifierbyte00h0404hreservedreservedInputreport0405husagecode100h0406husagecode200h0407husagecode300h0408husagecode400h0409husagecode500h040Ahusagecode600hOutputreport0500hLEDstatus00h0600hHIDoverI2CCommandlowbyte00hCommandregister0601hHIDoverI2CCommandhighbyte00hDataregister0700-070AhDataforHIDoverI2Ccommand00h(1)FunctionKeyUsageIDinkeyboardmapmustbenon-zero(2)Column/Rowintersectionoffunctionkey.
i.
e.
col3row4intersectionwouldread34h6SubmitDocumentationFeedbackCopyright2013,TexasInstrumentsIncorporatedProductFolderLinks:TCA8424TCA8424www.
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comSCDS341–MARCH2013Table2.
RegisterMap(continued)REGISTERADDRESSDESCRIPTIONPOWERUPDEFAULT(Hex)0000h(3)HIDDescriptorlength40h0001h41h0002hBCDversion42h0003h43h0004hReportdescriptorlength44h0005h45h0006hReportDescriptorRegisteraddress46h0007h47h0008hInputregisteraddress48h0009h49h000Ahmaxinputreportlength(including2bytes4Ahlengthfield)000Bh4Bh000ChOutputregisteraddress4Ch000Dh4Dh000Ehmaxoutputreportlength(including2bytes4EhHIDDescriptor(3)lengthfield)000Fh4Fh(0000h-001Dh)0010hCommandregisteraddress50h0011h51h0012hdataregisteraddress52h0013h53h0014hVendorID54h0015h55h0016hProductID56h0017h57h0018hVersionID58h0019h59h001AhReservedperHIDoverI2Cspecv0.
915Ah001Bh5Bh001Ch5Ch001Dh5Dh5Eh(3)TheHiddescriptorstartaddressmustbe0000hCopyright2013,TexasInstrumentsIncorporatedSubmitDocumentationFeedback7ProductFolderLinks:TCA8424TCA8424SCDS341–MARCH2013www.
ti.
comHIDDESCRIPTORRETRIEVALFigure4.
TypicalRetrievaloftheHIDDescriptorFigure4showsthetypicalretrievaloftheHIDdescriptor.
ThisisthemostcommonwaytheHIDdescriptorisretrieved.
However,theTCA8424allowspartialretrievalofthedescriptorasdescribedintheHIDoverI2Cspecrev1.
0.
Table3.
ReportDescriptorRegisterAddressPowerupDefault305F3160326133623463356436653766386739683A693B6AReport(1)descriptor3C6B(0030h-00F1h)3D6C3E6D3F6E406F41704271437244734574467547764877(1)Reportdescriptorcontentsmayvarydependingonversionofdevice.
PleasecontactTIfordevicefordifferentReportDescriptorcontents8SubmitDocumentationFeedbackCopyright2013,TexasInstrumentsIncorporatedProductFolderLinks:TCA8424TCA8424www.
ti.
comSCDS341–MARCH2013Table3.
ReportDescriptor(continued)RegisterAddressPowerupDefaultReportdescriptor4978(0030h-00F1h)4A794B7A4C7B4D7C4E7D4F7E507F5180528153825483558456855786588759885A895B8A5C8B5D8C5E8D5F8E608F6190629163926493659466956796689769986A996B9A6C9B6D9C6E9D6F9E709F71A072A173A274A375A476A5Copyright2013,TexasInstrumentsIncorporatedSubmitDocumentationFeedback9ProductFolderLinks:TCA8424TCA8424SCDS341–MARCH2013www.
ti.
comTable3.
ReportDescriptor(continued)RegisterAddressPowerupDefaultReportdescriptor77A6(0030h-00F1h)78A779A87AA97BAA7CAB7DAC7EAD7FAE80AF81B082B183B284B385B486B587B688B789B88AB98BBA8CBB8DBC8EBD8FBE90BF91C092C193C294C395C496C597C698C799C89AC99BCA9CCB9DCC9ECD9FCEA0CFA1D0A2D1A3D2A4D3A5D410SubmitDocumentationFeedbackCopyright2013,TexasInstrumentsIncorporatedProductFolderLinks:TCA8424TCA8424www.
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comSCDS341–MARCH2013Table3.
ReportDescriptor(continued)RegisterAddressPowerupDefaultReportdescriptorA6D5(0030h-00F1h)A7D6A8D7A9D8AAD9ABDAACDBADDCAEDDAFDEB0DFB1E0B2E1B3E2B4E3B5E4B6E5B7E6B8E7B9E8BAE9BBEABCEBBDECBEEDBFEEC0EFC1F0C2F1C3F2C4F3C5F4C6F5C7F6C8F7C9F8CAF9CBFACCFBCDFCCEFDCFFED0FFD10D21D32D43Copyright2013,TexasInstrumentsIncorporatedSubmitDocumentationFeedback11ProductFolderLinks:TCA8424TCA8424SCDS341–MARCH2013www.
ti.
comTable3.
ReportDescriptor(continued)RegisterAddressPowerupDefaultReportdescriptorD54(0030h-00F1h)D65D76D87D98DA9DB0ADC0BDD0CDE0DDF0EE00FE110E211E312E413E514E615E716E817E918EA19EB1AEC1BED1CEE1DEF1EF01FREPORTDESCRIPTORRETREIVAL12SubmitDocumentationFeedbackCopyright2013,TexasInstrumentsIncorporatedProductFolderLinks:TCA8424TCA8424www.
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comSCDS341–MARCH2013INPUTREPORTInputreportsareusedtocommunicatekeypressesandreleasestothehostcontroller.
TheTCA8424iscapableofcommunicatinguptosixsimultaneouskeypressesanduptoeightmodifierkeys.
ThestandardmodifierkeysrecognizedbytheTCA8424are(UsageIDbasedonHIDusagetablesver1.
11).
TheusageIDforeachkeyisstoredinthekeyboardmapsectionofNVmemory.
LeftCtrl(UsageID–E0)Leftshift(UsageID–E1)LeftAlt(UsageID–E2)LeftGUI(UsageID–E3)RightCtrl(UsageID–E4)Rightshift(UsageID–E5)RightAlt(UsageID–E6)RightGUI(UsageID–E7)Belowisthatformatofastandardinputreport.
Thefirsttwobytesaredatalengthfieldindicatingthelengthofinputreport.
ByteBit7Bit6Bit5Bit4Bit3Bit2Bit1Bit00000010111000000002ReportID3RightGUIRightAltRightShiftRightCtrlLeftGUILeftAltLeftShiftLeftCtrl4Reserved5Key1UsageID6Key2UsageID7Key3UsageID8Key4UsageID9Key5UsageID10Key6UsageIDAninputreportisgeneratedforeverykeypressandalsooneverykeyrelease.
IfnokeysarepressedafterakeyreleasethenthereportcontainsallzeroesexceptfortheDatalengthfield(firsttwobytes)andtheReportID.
Inputreportsarealsogeneratedifonlymodifierkeysarepressed(notaccompaniedbyanyotherkey).
Thedatalengthfield(firsttwobytes)forastandardkeypressisalways11.
SPECIALMODIFIER(Fnkey)ANDALTERNATEREPORTIDsOtherthanthestandardmodifiers,theTCA8424alsosupportsonespecialmodifiersuchasthefunction(FN)key.
Thisoperatesdifferentfromtheothermodifierkeysinthat,itisnotrepresentedinthemodifierbyteoftheinputreport.
TheTCA8424onlysupportsasinglekeypressincombinationwiththeFNkey.
WhentheFNkeyispressedtheTCA8424generatesadefaultinputreportindicatingthatallkeyshavebeenreleased.
AFNkeyreleasewillgenerateaninputreportwiththecurrentReportIDandclearedusagecodes.
TheTCA8424onlysupportsasinglekeypressincombinationwiththeFNkey.
AnykeypressedaftertheFNkeythatdoesnothaveanon-zeroUsageIDwillbeignored.
OncetheFNkeyispressedandakeythathasanUsageIDinthealternatekeyboardmaphasbeenpressed,additionalkeypresseswillbeignoreduntileithertheFNkeyisreleasedorthesecondkeythathadanUsageIDinthealternatekeyboardmapisreleased.
Inadditiontostandardfunctionkeys,manykeyboardssupportspecialfunctionssuchasvolumeup,volumedown,skiptrack,previoustracketc.
ReportIDsareusedasawayforthehostprocessortoidentifywhethertheusageIDcorrespondstoastandardfunctionkeyoraspecialfunctionkey.
TheTCA8424supportsFivedifferentreportIDs.
ReportIDsmustbenon-zero.
1.
DefaultReportID–locatedataddress0202h.
ThisIDispopulatedintheinputreportwhenthereisanormalkeypressoraregularfunctionkey.
2.
ReportID1–locatedataddress0203h.
ThisIDispopulatedinthereportwhentheUsageIDofthekeypressdetectedbytheTCA8424correspondstoausageIDlocatedinthememoryrange(0207h-020Eh)3.
ReportID2–locatedataddress0204h.
ThisIDispopulatedinthereportwhentheUsageIDofthekeyCopyright2013,TexasInstrumentsIncorporatedSubmitDocumentationFeedback13ProductFolderLinks:TCA8424TCA8424SCDS341–MARCH2013www.
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compressdetectedbytheTCA8424correspondstoausageIDlocatedinthememoryrange(020Fh-0216h)4.
ReportID3–locatedataddress0204h.
ThisIDispopulatedinthereportwhentheUsageIDofthekeypressdetectedbytheTCA8424correspondstoausageIDlocatedinthememoryrange(0217h-021Eh)5.
ReportID4–locatedataddress0204h.
ThisIDispopulatedinthereportwhentheUsageIDofthekeypressdetectedbytheTCA8424correspondstoausageIDlocatedinthememoryrange(021Fh-0226h)Ascanbeinferredfromtheabovedescription,wheneverakeypressisdetected,theTCA8424looksuptheusageIDfromthealternatekeyboardmapandthencomparesthisusageIDwiththeusageIDscorrespondingtoReportID1,ReportID2,ReportID3,andReportID4.
Ifthereisamatch,thencorrespondingreportIDispopulatedinthespecialinputreport.
IfnotthedefaultinputreportisusedwiththedefaultReportID.
(1)Belowistheformatofthespecialinputreport.
Theformatissimilartothebitfieldrepresentationusedtorepresentthemodifierbyteinthestandardinputreport.
UsageIDbytelocation0willcorrespondtothefirstUsageIDinmemoryfortherespectiveReportID(2)anddescendwithUsageIDbytelocation7correspondingtothelastUsageIDinmemory.
(2)Table4.
SpecialInputReportByteBit7Bit6Bit5Bit4Bit3Bit2Bit1Bit00000001001000000002ReportIDUsageIDUsageIDUsageIDUsageIDUsageIDUsageIDUsageIDUsageID3bytelocationbytelocationbytelocationbytelocationbytelocationbytelocation2bytelocation1bytelocation765430(1)Thelast5keyUsageIDsintheinputreportandthemodifierbytewillalwaysread00hwhenthefunctionkeyispressedinadditiontoanotherkey.
(2)ForReportID1:UsageIDbytelocation0correspondstomemorylocation0207h.
UsageIDbytelocation7correspondstomemorylocation020Eh.
Figure5.
InputReportRetrievalItisimportanttonotethat,unlikeretrievalofotherreports,wherethefirstI2Ctransactionisawrite,inthecaseofinputreportthefirsttransactionitselfisareadoperationasindicatedbyBit8oftheI2Caddress.
14SubmitDocumentationFeedbackCopyright2013,TexasInstrumentsIncorporatedProductFolderLinks:TCA8424TCA8424www.
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comSCDS341–MARCH2013OUTPUTREPORTOutputreportsareusedbythehosttoturnON/OFFanyindicatorLEDs(capslock,numlocketc.
)onthekeyboard.
TheTCA8424cansupportfrom2to4LEDindicatorsdependingontheversionofthedevicechosen.
Theoutputreportsaresinglebytereports(8-bit)whereeachbitindicatesthestatusofthecorrespondingLED.
A'1'indicatesthattheLEDisturnedonwhereasa'0'turnsofftheLED.
Belowistheformatoftheoutputreportreceivedfromthehost.
Justasinthecaseoftheinputreportthefirsttwobytesindicatethelengthoftheoutputreport.
ByteBit7Bit6Bit5Bit4Bit3Bit2Bit1Bit00000000111000000002ReservedReservedReservedReservedLED3LED2LED1LED0Figure6.
OutputReportRetrievalCOMMANDandDATAREGISTERTheHIDoverI2Cspecrequiresthatalldevicesrespondtocertaincommands.
Thecommandsareissuedtothecommandregister.
ThecommandisanopcodeasdefinedbytheHIDoverI2Cspec.
Theoperandforthecommandgoestothedataregister.
BelowisalistofcommandssupportedbytheTCA8424.
OpCodeCommandNameEffectonDeviceDeviceisresetandallregistersarereturnedtodefaultvalue.
Thiscommandhasthesameeffectonthe0001bRESETdeviceasapoweronreset.
0010bGET_REPORTMostrecentinputreportistransferredtoDataRegister0011bSET_REPORTDataregistercontentsareusedtoturnon/offLED.
1000bSET_POWERAllLEDsareturnedoffanddeviceisinlowestcurrentmode(willstilldetectkeypresses)TheI2CtransactionsusedtoissuethesecommandsareexactlyasdescribedintheHIDoverI2Cstandard.
RESETAfterreceivingtheRESETcommand,thedevicewillgothroughafullpoweronresetandallregistersareloadedwiththeirdefaultvalues.
TheTCA8424takes~600storesetandduringthistimeallI2Ctrafficwillbeignoredbythedevice.
Aftercomingoutofreset,thedatalengthfieldintheinputreportispopulatedwith0000handtheINTsignalisasserted.
GET_REPORTTheGET_REPORTcommandwillretrievethecurrentinputreportfromthedevicebutwillnotcleartheinterruptassertedfromakeypressorrelease.
Copyright2013,TexasInstrumentsIncorporatedSubmitDocumentationFeedback15ProductFolderLinks:TCA8424TCA8424SCDS341–MARCH2013www.
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comSET_REPORTTheSET_REPORTcommandisusedtosetthecontentsoftheoutputreport.
TheDatashallbepackagedwiththelengthfieldas0x0003,andthethirdbyteshalldescribetheLEDoutputsasdefinedinthereportdescriptor.
SET_POWERTheSET_POWER=SLEEPcommandwillturnoffalltheLEDoutputsandcleartheinputreportincludingreportIDandlengthfield.
IfakeyispressedwhenSET_POWER=SLEEPcommandisreceived,keyscanwillstopwhenthecommandisreceived.
TCA8424willwaitforallkeystobereleasedbeforeanysubsequentkeypresswillassertaninterrupt.
IfakeyispressedandnotreleasedwhiledeviceisasleepandtheSET_POWER=WAKEcommandisreceived,thekeyscannerwillstartandassertaninterruptthatakeyhasbeenpressed.
TheSET_POWER=WAKEcommandisreceivedtheLEDoutputswillbereturnedtothestatetheywerebeforetheSET_POWER=SLEEPwasreceived.
Ifacommandtochangetheoutputreportisreceivedduringsleep,theLEDstatuswillindicatethatofthelastoutputreportreceiveduponSET_POWER=WAKE.
Ifkeysarepressedwhilethedeviceisenteringsleepmode,areadoftheinputreportoruseoftheGET_REPORTcommandbeforeallkeysarereleased,maynotreflectthecurrentstateofthekeyboard.
AnykeypressesthathappenafterallkeysarereleasedwillpopulatetheinputreportandassertINT.
KEYBOARDMAPTheNonvolatilememorycontainsasectionthatcontainsthekeyboardmap.
Eachbytelocationinthekeyboardmap,ismappedtoaspecificrowcolumnintersectiononthekeymatrix,andcontainstheusageIDofthekeylocatedinthatrowcolumnintersection.
Thekeyboardmapconsistsoftwosections.
Eachrowcolumnintersectionismappedtoonelocationineachsection.
TheprimarysectioncontainstheusageIDofthekeyandthealternatesectioncontainsthealternateusageIDofthekeythatwillbereportedwhenthespecialmodifier(FN)isused.
Onlykeyswithnon-zerousagecodeswillberecognized,includingthefunctionkey.
Thedeviceisavailablewithsomepredefinedkeyboardmaps.
Itisalsoavailablewiththekeyboardmapnotprogrammedsothattheendusermayprogramthekeyboardmapbasedonthekeyboardbeingused.
AlternatelyyoumaycontactTIforcustomvariationsofthepartwithdifferentkeyboardmapsprogrammedbyspecialrequest.
Thetablebelowillustratesthecolumn-rowintersectionsandthememorylocationstheyaremappedto.
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ubmitDocumentationFeedbackCopyright2013,TexasInstrumentsIncorporatedProductFolderLinks:TCA8424TCA8424www.
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comSCDS341–MARCH2013KEYSCANLOGICFunctionalOverviewUponpoweruporwhencomingoutofRESET,thedevicesinitializesitselfwithalltheregistershavingthepowerupdefaultvalue.
AlltheCOLxpinsarepulleduptoVCCbyinternalpullupresistors.
AlltheROWxpinsarepulledlow.
Thedeviceisnowinidle/standbymode(lowestpowerstate).
Whenanykeyispressed,oneoftheCOLpinsgetsconnectedtooneoftheROWpins,therebypullingdownthecorrespondingCOLpin.
Thisinitiatesthekeyscan.
Whenthisoccurstheinternaloscillatorturnson,andeachROWxpingoeslow,oneaftertheother,forapproximately800uSwhiletheCOLxinputsaresampledateachstep.
Then,foreverykeythatispressed,thecorrespondingusageIDfromthekeyboardmapisregistered.
Afterapproximately25mS,thescanwillrepeat.
Ifanypreviouslypressedkeyisstillpressed,thenthecorrespondingcodeiswrittentotheInputregister.
Thescancontinuestorepeataslongastherearekeyspressed.
Now,whenapreviouslypressedkeyisreleasedanotherinputreportisgeneratedwiththekeysthatarestillpressed,orifnokeysarepressed,thenaninputreportwithallzeroUsagecodesisreported.
Oncetheinputreporthasbeenpopulatedintotheinputregister,theINTisassertedtoindicatetothehostthataninputreportisnowavailable.
Interrupt(INT)OutputAninterruptisgeneratedwhenthedevicehasaninputreportreadyfortheHOSTtoread.
ResettingtheinterruptisachievedbyreadingtheINPUTRegister.
UsingtheGET_REPORTcommandwillnotcleartheinterrupt.
Theinterruptwillclearafterthe2ndreadbyteoftheemptyinputreportonreset.
Afterreset,adefaultinputreportreadwillcleartheinputreportafterthelastbyteisread.
Ifaspecialinputreportisread,theinterruptclearsafterthe4thbyteisread.
Theinterruptstatusisupdatedinthereadmodeattheacknowledge(ACK)ornotacknowledge(NACK)bitfollowingtherisingedgeoftheSCLsignalafterthelastbyteoftheinputreporthasbeenread.
TheINPUTregisterwillkeepgettingupdatedwiththemostrecentkeypressreportsevenwhiletheINTsignalstaysasserted.
InorderavoidmissingofkeypressesitisrecommendedthathostprocessorrespondtointerruptservicerequestinVCC±10mASDAVO=0±30mAContinuousoutputlowIOLINTVO=0±10mAcurrentLEDxVO=0±20mATstgStoragetemperaturerange–65150°C(1)Stressesbeyondthoselistedunder"absolutemaximumratings"maycausepermanentdamagetothedevice.
Thesearestressratingsonly,andfunctionaloperationofthedeviceattheseoranyotherconditionsbeyondthoseindicatedunder"recommendedoperatingconditions"isnotimplied.
Exposuretoabsolute-maximum-ratedconditionsforextendedperiodsmayaffectdevicereliability.
(2)Theinputnegative-voltageandoutputvoltageratingsmaybeexceedediftheinputandoutputcurrentratingsareobserved.
Copyright2013,TexasInstrumentsIncorporatedSubmitDocumentationFeedback19ProductFolderLinks:TCA8424TCA8424SCDS341–MARCH2013www.
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comRECOMMENDEDOPERATINGCONDITIONSoveroperatingfree-airtemperaturerange(unlessotherwisenoted)MINMAXUNITVCCISupplyvoltage1.
653.
6VVtestVoltageontestpinDuringnormaloperation(inapplication)GNDGNDVVILEDVoltageonLEDoutput5VVIHHigh-levelinputvoltageSCL,SDA0.
7*VCCI3.
6VVILLow-levelinputvoltageSCL,SDA–0.
30.
3*VCCIVSDA20mALow-leveloutputIOLINT3mAcurrentLEDx12mATAOperatingfree-airtemperature–4085°CELECTRICALCHARACTERISTICSAllvaluesarespecifiedat25°Coperatingtemperature(unlessotherwisenoted)PARAMETERTESTCONDITIONSVCCMINTYPMAXUNITVIKInputdiodeclampvoltageII=–18mA1.
65Vto3.
6V–1.
2V1.
65V0.
41.
8V0.
4ROWx,INTIOL=3mA2.
5V0.
4V3.
3V0.
43.
6V0.
4VOL1.
65V0.
41.
8V0.
4SDAIOL=20mA2.
5V0.
4V3.
3V0.
43.
6V0.
41.
8V0.
4VVOLLEDxIOL=12mA3.
3V0.
45V0.
4IOLLEDxVOL=0.
4V1.
65V–5.
5V12mARintInternalpullupresistance80100120k1.
65V0.
2581.
8V0.
278Iccsh0CurrentconsumptionFscl=0kHz,oscillatoroff2.
5V0.
412A3.
3V0.
54163.
6V0.
6201.
65V17181.
8V1820Icc4khz1CurrentconsumptionFscl=400kHz,oscillatoron2.
5V2530A3.
3V33403.
6V39501.
65V36401.
8V3950Icc1Mhz1CurrentconsumptionFscl=1MHz,oscillatoron2.
5V4860A3.
3V65703.
6V6080ΔIccIncrementalcurrentfordurationofkeypressOnekeypressed1.
65V–3.
6V3945ACinSCL,SDA510pF20SubmitDocumentationFeedbackCopyright2013,TexasInstrumentsIncorporatedProductFolderLinks:TCA8424TCA8424www.
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comSCDS341–MARCH2013I2CINTERFACETIMINGREQUIREMENTSoveroperatingfree-airtemperaturerange(unlessotherwisenoted)STANDARDFASTMODEFASTMODEMODEPLUS(FM+)I2CBUSPARAMETERUNITI2CBUSI2CBUSMINMAXMINMAXMINMAXfsclI2Cclockfrequency0100040001000kHztschI2Cclockhightime40.
60.
26μstsclI2Cclocklowtime4.
71.
30.
5μstspI2Cspiketime505050nstsdsI2Cserialdatasetuptime25010050nstsdhI2Cserialdataholdtime000nsticrI2Cinputrisetime100020300120ns20x(VDD/20x(VDD/ticfI2Cinputfalltime300300120ns5.
5V)5.
5V)20x(VDD/20x(VDD/tocfI2Coutputfalltime;10pFto400pFbus300300120μs5.
5V)5.
5V)tbufI2CbusfreetimebetweenStopandStart4.
71.
30.
5μststsI2CStartorrepeaterStartconditionsetuptime4.
70.
60.
26μststhI2CStartorrepeaterStartconditionholdtime40.
60.
26μstspsI2CStopconditionsetuptime40.
60.
26μstvd(data)Validdatatime;SCLlowtoSDAoutputvalid3.
450.
30.
90.
45μsValiddatatimeofACKcondition;ACKsignalfromSCLtvd(ack)3.
450.
30.
90.
45μslowtoSDA(out)lowSWITCHINGCHARACTERISTICSoveroperatingfree-airtemperaturerange(unlessotherwisenoted)PARAMETERFROM(INPUT)TO(OUTPUT)MINMAXUNITtirInterruptresetdelaytimeSCLINT600nstpvOutputdatavalidSCLLEDx155nsCopyright2013,TexasInstrumentsIncorporatedSubmitDocumentationFeedback21ProductFolderLinks:TCA8424TCA8424SCDS341–MARCH2013www.
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comPARAMETERMEASUREMENTINFORMATIONA.
CLincludesprobeandjigcapacitance.
tocfismeasuredwithCLof10pFor400pF.
Allinputsaresuppliedbygeneratorshavingthefollowingcharacteristics:PRR≤10MHz,ZO=50,tr/tf≤30ns.
Allparametersandwaveformsarenotapplicabletoalldevices.
Figure11.
I2CInterfaceLoadCircuitandVoltageWaveformsA.
CLincludesprobeandjigcapacitance.
Allinputsaresuppliedbygeneratorshavingthefollowingcharacteristics:PRR≤10MHz,ZO=50,tr/tf≤30ns.
Allparametersandwaveformsarenotapplicabletoalldevices.
Figure12.
InterruptLoadCircuitandVoltageWaveforms22SubmitDocumentationFeedbackCopyright2013,TexasInstrumentsIncorporatedProductFolderLinks:TCA8424TCA8424www.
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comSCDS341–MARCH2013PARAMETERMEASUREMENTINFORMATION(continued)Figure13.
LEDLoadConfigurationFigure14.
RowPull-downLoadConfigurationCLincludesprobeandjigcapacitance.
tpvismeasuredfrom0.
7*VCConSCLto50%I/O(Pn)output.
Allinputsaresuppliedbygeneratorshavingthefollowingcharacteristics:PRR≤10MHz,ZO=50,tr/tf≤30ns.
Theoutputsaremeasuredoneatatime,withonetransitionpermeasurement.
Allparametersandwaveformsarenotapplicabletoalldevices.
Copyright2013,TexasInstrumentsIncorporatedSubmitDocumentationFeedback23ProductFolderLinks:TCA8424PACKAGEOPTIONADDENDUMwww.
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com10-Dec-2020Addendum-Page1PACKAGINGINFORMATIONOrderableDeviceStatus(1)PackageTypePackageDrawingPinsPackageQtyEcoPlan(2)Leadfinish/Ballmaterial(6)MSLPeakTemp(3)OpTemp(°C)DeviceMarking(4/5)SamplesTCA8424RHARNRNDVQFNRHA402500RoHS&GreenNIPDAULevel-3-260C-168HR-40to85PZ424(1)Themarketingstatusvaluesaredefinedasfollows:ACTIVE:Productdevicerecommendedfornewdesigns.
LIFEBUY:TIhasannouncedthatthedevicewillbediscontinued,andalifetime-buyperiodisineffect.
NRND:Notrecommendedfornewdesigns.
Deviceisinproductiontosupportexistingcustomers,butTIdoesnotrecommendusingthispartinanewdesign.
PREVIEW:Devicehasbeenannouncedbutisnotinproduction.
Samplesmayormaynotbeavailable.
OBSOLETE:TIhasdiscontinuedtheproductionofthedevice.
(2)RoHS:TIdefines"RoHS"tomeansemiconductorproductsthatarecompliantwiththecurrentEURoHSrequirementsforall10RoHSsubstances,includingtherequirementthatRoHSsubstancedonotexceed0.
1%byweightinhomogeneousmaterials.
Wheredesignedtobesolderedathightemperatures,"RoHS"productsaresuitableforuseinspecifiedlead-freeprocesses.
TImayreferencethesetypesofproductsas"Pb-Free".
RoHSExempt:TIdefines"RoHSExempt"tomeanproductsthatcontainleadbutarecompliantwithEURoHSpursuanttoaspecificEURoHSexemption.
Green:TIdefines"Green"tomeanthecontentofChlorine(Cl)andBromine(Br)basedflameretardantsmeetJS709Blowhalogenrequirementsof<=1000ppmthreshold.
Antimonytrioxidebasedflameretardantsmustalsomeetthe<=1000ppmthresholdrequirement.
(3)MSL,PeakTemp.
-TheMoistureSensitivityLevelratingaccordingtotheJEDECindustrystandardclassifications,andpeaksoldertemperature.
(4)Theremaybeadditionalmarking,whichrelatestothelogo,thelottracecodeinformation,ortheenvironmentalcategoryonthedevice.
(5)MultipleDeviceMarkingswillbeinsideparentheses.
OnlyoneDeviceMarkingcontainedinparenthesesandseparatedbya"~"willappearonadevice.
IfalineisindentedthenitisacontinuationofthepreviouslineandthetwocombinedrepresenttheentireDeviceMarkingforthatdevice.
(6)Leadfinish/Ballmaterial-OrderableDevicesmayhavemultiplematerialfinishoptions.
Finishoptionsareseparatedbyaverticalruledline.
Leadfinish/Ballmaterialvaluesmaywraptotwolinesifthefinishvalueexceedsthemaximumcolumnwidth.
ImportantInformationandDisclaimer:TheinformationprovidedonthispagerepresentsTI'sknowledgeandbeliefasofthedatethatitisprovided.
TIbasesitsknowledgeandbeliefoninformationprovidedbythirdparties,andmakesnorepresentationorwarrantyastotheaccuracyofsuchinformation.
Effortsareunderwaytobetterintegrateinformationfromthirdparties.
TIhastakenandcontinuestotakereasonablestepstoproviderepresentativeandaccurateinformationbutmaynothaveconducteddestructivetestingorchemicalanalysisonincomingmaterialsandchemicals.
TIandTIsuppliersconsidercertaininformationtobeproprietary,andthusCASnumbersandotherlimitedinformationmaynotbeavailableforrelease.
InnoeventshallTI'sliabilityarisingoutofsuchinformationexceedthetotalpurchasepriceoftheTIpart(s)atissueinthisdocumentsoldbyTItoCustomeronanannualbasis.
TAPEANDREELINFORMATION*AlldimensionsarenominalDevicePackageTypePackageDrawingPinsSPQReelDiameter(mm)ReelWidthW1(mm)A0(mm)B0(mm)K0(mm)P1(mm)W(mm)Pin1QuadrantTCA8424RHARVQFNRHA402500330.
016.
46.
36.
31.
112.
016.
0Q2PACKAGEMATERIALSINFORMATIONwww.
ti.
com29-Sep-2019PackMaterials-Page1*AlldimensionsarenominalDevicePackageTypePackageDrawingPinsSPQLength(mm)Width(mm)Height(mm)TCA8424RHARVQFNRHA402500367.
0367.
038.
0PACKAGEMATERIALSINFORMATIONwww.
ti.
com29-Sep-2019PackMaterials-Page2www.
ti.
comGENERICPACKAGEVIEWThisimageisarepresentationofthepackagefamily,actualpackagemayvary.
Refertotheproductdatasheetforpackagedetails.
VQFN-1mmmaxheightRHA40PLASTICQUADFLATPACK-NOLEAD6x6,0.
5mmpitch4225870/Awww.
ti.
comPACKAGEOUTLINE6.
155.
856.
155.
851.
00.
80.
050.
002X4.
536X0.
52X4.
540X0.
50.
340X0.
300.
182.
620.
13.
520.
1(0.
1)TYPVQFN-1mmmaxheightRHA0040EPLASTICQUADFLATPACK-NOLEAD4219054/A04/20200.
08C0.
1CAB0.
05NOTES:1.
Alllineardimensionsareinmillimeters.
Anydimensionsinparenthesisareforreferenceonly.
DimensioningandtolerancingperASMEY14.
5M.
2.
Thisdrawingissubjecttochangewithoutnotice.
3.
Thepackagethermalpadmustbesolderedtotheprintedcircuitboardforthermalandmechanicalperformance.
PIN1INDEXAREASEATINGPLANEPIN1IDSYMMEXPOSEDTHERMALPADSYMM11011202130314041SCALE2.
000ABCwww.
ti.
comEXAMPLEBOARDLAYOUT36X(0.
5)(R0.
05)TYP0.
07MAXALLAROUND0.
07MINALLAROUND40X(0.
6)40X(0.
24)(5.
8)(5.
8)(2.
62)(3.
52)(0.
2)TYPVIA(0.
6)TYP(0.
91)(1.
06)VQFN-1mmmaxheightRHA0040EPLASTICQUADFLATPACK-NOLEAD4219054/A04/2020NOTES:(continued)4.
Thispackageisdesignedtobesolderedtoathermalpadontheboard.
Formoreinformation,seeTexasInstrumentsliteraturenumberSLUA271(www.
ti.
com/lit/slua271).
5.
Viasareoptionaldependingonapplication,refertodevicedatasheet.
Ifanyviasareimplemented,refertotheirlocationsshownonthisview.
Itisrecommendedthatviasunderpastebefilled,pluggedortented.
SYMMSYMMLANDPATTERNEXAMPLEEXPOSEDMETALSHOWNSCALE:15XSEESOLDERMASKDETAIL11011202130314041METALEDGESOLDERMASKOPENINGEXPOSEDMETALMETALUNDERSOLDERMASKSOLDERMASKOPENINGEXPOSEDMETALNONSOLDERMASKDEFINED(PREFERRED)SOLDERMASKDEFINEDSOLDERMASKDETAILSwww.
ti.
comEXAMPLESTENCILDESIGN40X(0.
6)40X(0.
24)36X(0.
5)(5.
8)(5.
8)6X(1.
15)6X(1)(R0.
05)TYP(0.
675)(1.
2)VQFN-1mmmaxheightRHA0040EPLASTICQUADFLATPACK-NOLEAD4219054/A04/2020NOTES:(continued)6.
Lasercuttingapertureswithtrapezoidalwallsandroundedcornersmayofferbetterpasterelease.
IPC-7525mayhavealternatedesignrecommendations.
SOLDERPASTEEXAMPLEBASEDON0.
125MMTHICKSTENCILSCALE:15XEXPOSEDPAD4175%PRINTEDSOLDERCOVERAGEBYAREAUNDERPACKAGESYMMSYMM11011202130314041IMPORTANTNOTICEANDDISCLAIMERTIPROVIDESTECHNICALANDRELIABILITYDATA(INCLUDINGDATASHEETS),DESIGNRESOURCES(INCLUDINGREFERENCEDESIGNS),APPLICATIONOROTHERDESIGNADVICE,WEBTOOLS,SAFETYINFORMATION,ANDOTHERRESOURCES"ASIS"ANDWITHALLFAULTS,ANDDISCLAIMSALLWARRANTIES,EXPRESSANDIMPLIED,INCLUDINGWITHOUTLIMITATIONANYIMPLIEDWARRANTIESOFMERCHANTABILITY,FITNESSFORAPARTICULARPURPOSEORNON-INFRINGEMENTOFTHIRDPARTYINTELLECTUALPROPERTYRIGHTS.
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