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3.4Power-OnReset(RESET)
3.5PowerDown(PDN)
3.6I
2
CBusControl(CS0)
3.7ProgrammableGeneralPurposeI/O(GPIO)
3.7.1NoEEPROMisPresentoraMemoryErrorOccurs
TAS3108,TAS3108IA
AUDIODIGITALSIGNALPROCESSORS
SLES152B–OCTOBER2005–REVISEDNOVEMBER2007
AslongasRESETisheldLOW,thedeviceisintheresetstate.Duringreset,allI
2
Candserialdatabus
operationsareignored.TheI
2
CinterfaceSCLandSDAlinesgointoahigh-impedancestateandremain
inthatstateuntildeviceinitializationhascompleted.
Therisingedgeoftheresetpulsebeginstheinitializationhousekeepingfunctionsofclearingmemoryand
settingthedefaultregistervalues.Oncethesearecomplete,theTAS3108/TAS3108IAenablesitsmaster
I
2
CinterfaceanddisablesitsslaveI
2
Cinterface.
ThentheTAS3108/TAS3108IAlooksforanEEPROMasdescribedinSection2.6,I
2
CControlInterface.
Onpowerup,itisrecommendedthattheTAS3108/TAS3108IARESETbeheldLOWuntilDVDDhas
reached3.3V.ThiscanbedonebyprogrammingthesystemcontrollerorbyusinganexternalRCdelay
circuit.The1-kΩand1-µFvaluesprovideadelayofapproximately200µs.ThevaluesofRandCcanbe
adjustedtoprovideotherdelayvaluesasnecessary.
PDNisauser-firmware-definablepinthatisprogrammedinthedefaultTAS3108andTAS3108IA
configurationtostopallclocksintheTAS3108/TAS3108IA,whilepreservingthestateofthedevice.For
moreinformation,seeTAS3108/TAS3108IAFirmwareProgrammer'sGuide(SLEU067 ).
TheTAS3108/TAS3108IAhasacontroltospecifytheslaveandmasterI
2
Caddress.Thiscontrolpermits
uptotwoTAS3108/TAS3108IAdevicestobeplacedinasystemwithoutexternallogic.
SeeSection6.2foracompletedescriptionofthispin.
TheTAS3108/TAS3108IAhasoneGPIOpinthatis8051firmwareprogrammable.
Onpoweruporfollowingareset,theGPIOpinbecomesaninput.Afterwards,themicroprocessorcan
programtheGPIOasaninputoranoutput.
Formoreinformation,seeTAS3108/TAS3108IAFirmwareProgrammer'sGuide(SLEU067 ).
Followingresetorpower-upinitializationwiththeEEPROMnotpresentorifamemoryerroroccurs,the
TAS3108/TAS3108IAisinoneoftwomodes,dependingonthesettingoftheGPIOpin.
•GPIOpinislogicHIGH(througha20-kΩresistor)
WiththeGPIOpinheldHIGHduringinitialization,theTAS3108/TAS3108IAcomesupinthedefault
configurationwiththeserialdataoutputsnotactive.OncetheTAS3108/TAS3108IAhascompleted
thedefaultinitializationprocedureandafterthestatusregisterisupdatedandtheI
2
Cslave
interfaceisenabled,theGPIOpinisanoutputandisdrivenLOW.FollowingtheHIGH-to-LOW
transitionoftheGPIOpin,thesystemcontrollercanaccesstheTAS3108/TAS3108IAthroughthe
I
2
Cinterfaceandreadthestatusregistertodeterminetheloadstatus.
Ifamemory-readerroroccurs,theTAS3108/TAS3108IAreportstheerrorinthestatusregister(I
2
C
subaddress0x02).
•GPIOpinislogicLOW(througha20-kΩresistor)
WithGPIOpinheldLOWduringinitialization,theTAS3108/TAS3108IAcomesupinanI/Otest
configuration.Inthiscase,oncetheTAS3108/TAS3108IAcompletesitsdefaulttestinitialization
procedure,thestatusregisterisupdated,theI
2
Cslaveinterfaceisenabled,andthe
TAS3108/TAS3108IAstreamsaudiounalteredfrominputtooutputasSDIN1toSDOUT1,SDIN2to
SDOUT2,etc.
Inthisconfiguration,theGPIOpinisanoutputsignalthatisdrivenLOW.Iftheexternallogicisno
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