HT45F56 datasheet(16/90 Pages) HOLTEK

16 / 90 page

Rev. 1.11

April 11, 2017

Rev. 1.11

April 11, 2017

HT45F56

Shock Detector Flash MCU

HT45F56

Shock Detector Flash MCU

Theaccompanyingdiagramillustratestheaddressingdataflowofthelook-uptable.

Last Page or

PC High Byte

TBLP Register

Data

14 bits

Program Memory

User Selected

High Byte

Low Byte

Table Program Example

Theaccompanyingexampleshowshowthetablepointerandtabledataisdefinedandretrievedfrom

thedevice.Thisexampleusesrawtabledatalocatedinthelastpagewhichisstoredthereusingthe

ORGstatement.ThevalueatthisORGstatementis“300H”whichreferstothestartaddressofthe

lastpagewithinthe1KProgramMemoryofthedevice.Thetablepointerlowbyteregisterissetup

heretohaveaninitialvalueof“06H”.Thiswillensurethatthefirstdatareadfromthedatatable

willbeattheProgramMemoryaddress“306H”or6locationsafterthestartofthelastpage.Note

thatthevalueforthetablepointerisreferencedtothefirstaddressofthepresentpageifthe“TABRD

[m]”instructionisbeingused.Thehighbyteofthetabledatawhichinthiscaseisequaltozerowill

betransferredtotheTBLHregisterautomaticallywhenthe“TABRD[m]instructionisexecuted.

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

; to the last page or current page

tabrd tempreg1

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

; memory address “306H” 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 “305H” transferred to tempreg2 and TBLH in this

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

; register tempreg2

org 300h

; sets initial address of program memory

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

HT45F56 数据表(PDF) 16 Page - Holtek Semiconductor Inc

HT45F56 数据表(HTML) 16 Page - Holtek Semiconductor Inc

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