HT45F56 datasheet(20/90 Pages) HOLTEK

20 / 90 page

Rev. 1.11

April 11, 2017

Rev. 1.11

April 11, 2017

HT45F56

Shock Detector Flash MCU

HT45F56

Shock Detector Flash MCU

Special Function Register Description

MostoftheSpecialFunctionRegisterdetailswillbedescribedintherelevantfunctionalsection.

However,severalregistersrequireaseparatedescriptioninthissection.

Indirect Addressing Registers – IAR0, IAR1

TheIndirectAddressingRegisters,IAR0andIAR1,althoughhavingtheirlocationsinnormalRAM

registerspace,donotactuallyphysicallyexistasnormalregisters.Themethodofindirectaddressing

forRAMdatamanipulationusestheseIndirectAddressingRegistersandMemoryPointers,in

contrasttodirectmemoryaddressing,wheretheactualmemoryaddressisspecified.Actionson

theIAR0andIAR1registerswillresultinnoactualreadorwriteoperationtotheseregistersbut

rathertothememorylocationspecifiedbytheircorrespondingMemoryPointers,MP0orMP1.

Actingasapair,IAR0andMP0cantogetheraccessdataonlyfromBank0whiletheIAR1register

togetherwithMP1registercanaccessdatafromanyDataMemorybank.AstheIndirectAddressing

Registersarenotphysicallyimplemented,readingtheIndirectAddressingRegistersindirectlywill

returnaresultof“00H”andwritingtotheregistersindirectlywillresultinnooperation.

Memory Pointers – MP0, MP1

TheIndirectAddressingRegisters,IAR0andIAR1,althoughhavingtheirlocationsinnormalRAM

registerspace,donotactuallyphysicallyexistasnormalregisters.Themethodofindirectaddressing

forRAMdatamanipulationusestheseIndirectAddressingRegistersandMemoryPointers,in

contrasttodirectmemoryaddressing,wheretheactualmemoryaddressisspecified.Actionsonthe

IAR0andIAR1registerswillresultinnoactualreadorwriteoperationtotheseregistersbutrather

tothememorylocationspecifiedbytheircorrespondingMemoryPointers,MP0orMP1.Actingasa

pair,IAR0andMP0cantogetheraccessdatafromBank0whiletheIAR1andMP1registerpaircan

accessdatafromanybank.AstheIndirectAddressingRegistersarenotphysicallyimplemented,

readingtheIndirectAddressingRegistersindirectlywillreturnaresultof“00H”andwritingtothe

registersindirectlywillresultinnooperation.

Indirect Addressing Program Example

• Example 1

data .section ‘data’

adres1 db ?

adres2 db ?

adres3 db ?

adres4 db ?

block db ?

code .section at 0 code

org 00h

start:

mov a,04h

; setup size of block

mov block,a

mov a,offset adres1 ; Accumulator loaded with first RAM address

mov mp0,a

; setup memory pointer with first RAM address

loop:

clr IAR0

; clear the data at address defined by MP0

inc mp0

; increment memory pointer

sdz block

; check if last memory location has been cleared

jmp loop

continue:

Theimportantpointtonotehereisthatintheexampleshownabove,noreferenceismadetospecific

RAMaddresses.

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