HT45F4MA datasheet(23/145 Pages) HOLTEK

23 / 145 page

Rev. 1.20

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Rev. 1.20

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HT45F4MA/HT45FH4MA/HT45FH4MA-1

Power Bank Flash MCU

HT45F4MA/HT45FH4MA/HT45FH4MA-1

Power Bank Flash MCU

Table Program Example

Thefollowingexampleshowshowthetablepointerandtabledataisdefinedandretrievedfromthe

microcontroller.ThisexampleusesrawtabledatalocatedintheProgramMemorywhichisstored

thereusingtheORGstatement.ThevalueatthisORGstatementis“700H”whichreferstothestart

addressofthelastpagewithinthe2KwordsProgramMemoryofthedevice.Thetablepointeris

setupheretohaveaninitialvalueof“06H”.Thiswillensurethatthefirstdatareadfromthedata

tablewillbeattheProgramMemoryaddress“706H”or6locationsafterthestartofthelastpage.

Notethatthevalueforthetablepointerisreferencedtothefirstaddressofthepresentpageifthe

“TABRD[m]”instructionisbeingused.Thehighbyteofthetabledatawhichinthiscaseisequal

tozerowillbetransferredtotheTBLHregisterautomaticallywhenthe“TABRD[m]”instructionis

executed.

BecausetheTBLHregisterisaread-onlyregisterandcannotberestored,careshouldbetaken

toensureitsprotectionifboththemainroutineandInterruptServiceRoutineusetableread

instructions.Ifusingthetablereadinstructions,theInterruptServiceRoutinesmaychangethe

valueoftheTBLHandsubsequentlycauseerrorsifusedagainbythemainroutine.Asaruleitis

recommendedthatsimultaneoususeofthetablereadinstructionsshouldbeavoided.However,in

situationswheresimultaneoususecannotbeavoided,theinterruptsshouldbedisabledpriortothe

executionofanymainroutinetable-readinstructions.Notethatalltablerelatedinstructionsrequire

twoinstructioncyclestocompletetheiroperation.

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

mov a,07h

; initialise high table pointer

mov tbhp,a

tabrd tempreg1

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

; memory address “706H” 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 “705H” transferred to tempreg2 and TBLH

; in this example the data “1AH” is transferred to tempreg1 and data “0FH”

; to register tempreg2

org 700h

; sets initial address of program memory

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

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