Holtek BS82B12A-3 - Page 38

Rev. 1.20 38 January 23, 2015 Rev. 1.20 39 January 23, 2015
BS82B12A-3/BS82C16A-3/BS82D20A-3
Touch Key 8-Bit Flash MCU with LED/LCD Driver
BS82B12A-3/BS82C16A-3/BS82D20A-3
Touch Key 8-Bit Flash MCU with LED/LCD Driver
BP Register – BS82D20A-3
Bit 7 6 5 4 3 2 1 0
Name — — — — — DMBP2 DMBP1 DMBP0
R/W — — — — — R/W R/W R/W
POR — — — — — 0 0 0
Bit7~3 Unimplemented,readas"0"
Bit2~0 DMBP2~DMBP0:SelectDataMemoryBanks
000:Bank0
001:Bank1
010:Bank2
011:Bank3
100:Bank4
101:Bank5
11x:Undened
Accumulator – ACC
TheAccumulatoriscentraltotheoperationofanymicrocontrollerandiscloselyrelatedwith
operationscarriedoutbytheALU.TheAccumulatoristheplacewhereallintermediateresults
fromtheALUarestored.WithouttheAccumulatoritwouldbenecessarytowritetheresultof
eachcalculationorlogicaloperationsuchasaddition,subtraction,shift,etc.,totheDataMemory
resultinginhigherprogrammingandtimingoverheads.Datatransferoperationsusuallyinvolve
thetemporarystoragefunctionoftheAccumulator;forexample,whentransferringdatabetween
oneuser-definedregisterandanother,itisnecessarytodothisbypassingthedatathroughthe
Accumulatorasnodirecttransferbetweentworegistersispermitted.
Program Counter Low Register – PCL
Toprovideadditionalprogramcontrolfunctions,thelowbyteoftheProgramCounterismade
accessibletoprogrammersbylocatingitwithintheSpecialPurposeareaoftheDataMemory.By
manipulatingthisregister,directjumpstootherprogramlocationsareeasilyimplemented.Loading
avaluedirectlyintothisPCLregisterwillcauseajumptothespeciedProgramMemorylocation,
however,astheregisterisonly8-bitwide,onlyjumpswithinthecurrentProgramMemorypageare
permitted.Whensuchoperationsareused,notethatadummycyclewillbeinserted.
Look-up Table Registers – TBLP, TBHP, TBLH
Thesethreespecialfunctionregistersareusedtocontroloperationofthelook-uptablewhichis
storedintheProgramMemory.TBLPandTBHParethetablepointersandindicatethelocation
wherethetabledataislocated.Theirvaluemustbesetupbeforeanytablereadcommandsare
executed.Theirvaluecanbechanged,forexampleusingthe"INC"or"DEC"instructions,allowing
foreasytabledatapointingandreading.TBLHisthelocationwherethehighorderbyteofthetable
dataisstoredafteratablereaddatainstructionhasbeenexecuted.Notethatthelowerordertable
databyteistransferredtoauserdenedlocation.