HT45F77 datasheet(24/203 Pages) HOLTEK

24 / 203 page

Rev. 1.20

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Rev. 1.20

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HT45F77

Body Fat Scale Flash MCU

HT45F77

Body Fat Scale Flash MCU

Table Program Example

Thefollowingexampleshowshowthetablepointerandtabledataisdefinedandretrievedfromthe

microcontroller.ThisexampleusesrawtabledatalocatedintheProgramMemorywhichisstored

thereusingtheORGstatement.ThevalueatthisORGstatementis"1F00H"whichreferstothestart

addressofthelastpagewithinthe8KProgramMemoryofthemicrocontroller.Thetablepointer

issetupheretohaveaninitialvalueof"06H".Thiswillensurethatthefirstdatareadfromthedata

tablewillbeattheProgramMemoryaddress"1F06H"or6locationsafterthestartofthelastpage.

NotethatthevalueforthetablepointerisreferencedtothefirstaddressspecifiedbyTBLPand

TBHPifthe"TABRD[m]"or"LTABRD[m]"instructionisbeingused.Thehighbyteofthetable

datawhichinthiscaseisequaltozerowillbetransferredtotheTBLHregisterautomaticallywhen

the"TABRD[m]"or"LTABRD[m]"instructionisexecuted.

BecausetheTBLHregisterisread/writeregisterandcanberestored,careshouldbetakentoensure

itsprotectionifboththemainroutineandInterruptServiceRoutineusetablereadinstructions.If

usingthetablereadinstructions,theInterruptServiceRoutinesmaychangethevalueoftheTBLH

andsubsequentlycauseerrorsifusedagainbythemainroutine.Asaruleitisrecommendedthat

simultaneoususeofthetablereadinstructionsshouldbeavoided.However,insituationswhere

simultaneoususecannotbeavoided,theinterruptsshouldbedisabledpriortotheexecutionofany

mainroutinetable-readinstructions.Notethatalltablerelatedinstructionsrequiretwoinstruction

cyclestocompletetheiroperation.

Table Read Program Example

tempreg1 db ?

; temporary register #1

tempreg2 db ?

; temporary register #2

mov a,06h

; initialise low table pointer - note that this address is referenced

mov tblp,a

; to the last page or the page that tbhp pointed

mov a,1Fh

; initialise high table pointer

mov tbhp,a

tabrd tempreg1

; transfers value in table referenced by table pointer data at program

; memory address "1F06H" transferred to tempreg1 and TBLH

dec tblp

; reduce value of table pointer by one

tabrd tempreg2

; transfers value in table referenced by table pointer

; data at program memory address "1F05H" transferred to

; tempreg2 and TBLH in this example the data "1AH" is

; transferred to tempreg1 and data "1FH" to register tempreg2

org 1F00h

; sets initial address of program memory

dc 00Ah, 00Bh, 00Ch, 00Dh, 00Eh, 00Fh, 01Ah, 01Bh

HT45F77 Datasheet(PDF) 24 Page - Holtek Semiconductor Inc

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