HDQ Communication Basics (Rev. A - Texas Instruments

1 ApplicationReportSLUA408A December2006 ,suchastheneedforabreakpriortoeachcommun ication,howtoreliablyread16-bitdynamicva luesoverthe8-bitbus, , , (writecommand),ortooutputtheeightbitsofd atafromaregisterspecifiedbythecommandbyt e(readcommand).Commandanddatabytesconsis tofastreamofbitsthathaveamaximumtransmis sionrateof5 (R/W) ,theHDQslavestartsoutputtingthedataafter thespecifiedresponsetime,t(RSPS). , , December2006 RevisedSeptember2008 HDQC ommunicationBasics1 SubmitDocumentationFeedbackt(B)t(BR) ,t(B).Ifthehostdoesnotgetanexpectedrespo nsefromtheHDQslaveorifthehostneedstorest artacommunicationbeforeitiscomplete, sminimumbreakrecoverytime,t(BR). ,unpredictablebitvaluesmaybeinputtotheHD Qengine, ,itispossiblefortheHDQslaveenginetoperfo rmanincorrectcommand, ,likethebqJuniorgasgauges, , , , ;so, (bq26500,bq26501,bq27000,andbq27010) December2006 RevisedSeptember2008 SubmitDocumentationFeedbackt(HW0)t(CYCH) t(HW1)a).

2 Updated Timing Methodologyt(STRH)t(DSU)t(DH)t(SSU)t(CYC H)Write 1 Write 0 b). Legacy Timing Methodologyt(DW0)t(CYCD)t(DW1)a). Updated Timing Methodologyt(STRB)t(DSUB)t(DV)t(SSUB)t(C YCB)Read 1 Read 0 b). Legacy Timing (HW1)minimumandmaximumvalues,respectivel y,andthattDHandtSSUareequivalenttot(HW0) minimumandmaximumvalues, ,comparisonofFigure4bwithFigure4ashowsth attSTRB andtDSUB areequivalenttot(DW1)minimumandmaximumva lues,respectively,andthattDVandtSSUB areequivalenttot(DW0)minimumandmaximumva lues, December2006 ,bq2013H,bq2014H,bq2050H,bq2052bq2019,bq 262x0,bq2650x,bq270x0(LegacyTimingMethod ology)(UpdatedTimingMethodology)Paramete rDeviceMinimumMaximumParameterDeviceMini mumMaximumtBAll190 st(B)All190 stBRAll40 st(BR)All40 stSTRHAll5nststart-detectbq2019,bq262x05 ns(1)t(HW1)bq2019,bq262x032 s(1)bq2650017 s(2)bq26051, s(2)tDSUAll50 sAll50 stDHAll100 st(HW0)bq2019,bq262x0,100 sbq26500bq26501,bq270x086 s(3)tSSUAll145 sAll145 stCYCHAll190 st(CYCH)All190 stSTRBAll32 st(DW1)

3 All32 stDSUBAll50 s50 stDVAll80 st(DW0)All80 stSSUBAll145 s145 stCYCBAll190 s250 st(CYCD)Allbutbq2650x190 s250 sbq2650x260 s(4)tRSPSAll190 s320 st(RSPS)All190 s320 sThefewbasicdifferencesinHDQtimingamonga llthepartsthatsupportaslaveHDQinterfacea redescribedinthefollowingnotes.(1)Thebq2 019,bq26200,andbq26220batterymonitorsare specifiedwithatstart-detecttimeof5nsanda t(HW1)minimumtimeof32 ,bq2013H,bq2014H,bq2050H, , ,like32 (HW1)timedowntoabout1 ,theadditionofESDprotectionontheHDQlinea ddsenoughfilteringtotakeoutextremelyshor tspikeslike5ns,butdoesnotsubstantiallyat tenuatea1- spulse.(2)Thebq26500hasinternalrejection ontheHDQlinethatpreventsrecognizinganyco mmunicationstartiftheHDQlinepulseslowfor muchshorterthan17 ,bq27000, swideandthusarecompatiblewithaTIOMAPHDQ interface.(3)Thebq26501,bq27000,andbq270 10haveat(HW0)minimumtimeof86 sinsteadofthenormal100- sislessthan100 s,anyhostthatmeetsthe100- sminimumtimingisalsocompatiblewiththesep arts.

4 (4)Thebq26500andbq26501haveamaximumbitcy cletime,t(CYCD),ondatasenttothehostof260 sinsteadofthenormal250- December2006 , ,somedeviceslikethebq2013H,bq2014H, ,theCMOS inputstagecoulddrawsomeshoot-throughcurr entintheHDQinputstagethatmaycauseupto100 ,thedesignermaywishtoaddahighvalueresist ance,like1M , ,ifthe16-bitwordisanincrementingordecrem entingcounter, , , (H0) (L0) (H1) ,thenthevalid16-bitresultisH0 ,readlowbyteagain(L1)andthevalid16-bitre sultisH1 , , ,thereisnorestrictiononthetimebetweeneac hbit, (R/Wbit)issentonaread, ,anotherapproachistoleaveinterruptsenabl ed, , , (startbit,8databits,and2stopbits).Atabau drateof57,600( sperbit), , December2006 , ,thereceiveddatacouldbeinterpretedaseith er0xFEor0xFCifalogic1issent,oreither0xF0 ,0xE0,0xC0,0x80, ,thedatabitshouldbeinterpretedasalogic1a ndiflessthanorequalto0xF8, , ,if8bitsofaddressaresentandthen8bitsofda tafromtheHDQslavearereceivedfromthataddr ess, December2006 RevisedSeptember2008 SubmitDocumentationFeedbackIMPORTANTNOTI CET exasInstrumentsIncorporatedanditssubsidi aries(TI)reservetherighttomakecorrection s,modifications,enhancements,improvement s, , , ,eitherexpressorimplied,isgrantedunderan yTIpatentright,copyright,maskworkright,o rotherTIintellectualpropertyrightrelatin gtoanycombination,machine, , ,conditions,limitations, (suchaslifesupport)

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