HT45F56 datasheet(62/90 Pages) HOLTEK

62 / 90 page

Rev. 1.11

April 11, 2017

Rev. 1.11

April 11, 2017

HT45F56

Shock Detector Flash MCU

HT45F56

Shock Detector Flash MCU

Programming Considerations

TheTMCounterRegistersandtheCapture/CompareCCRAregisters,allhavealowandhighbyte

structure.Thehighbytescanbedirectlyaccessed,butasthelowbytescanonlybeaccessedviaan

internal8-bitbuffer,readingorwritingtotheseregisterpairsmustbecarriedoutinaspecificway.

Theimportantpointtonoteisthatdatatransfertoandfromthe8-bitbufferanditsrelatedlowbyte

onlytakesplacewhenawriteorreadoperationtoitscorrespondinghighbyteisexecuted.

AstheCCRAregistersisimplementedinthewayshowninthefollowingdiagramandaccessing

theseregisterpairsiscarriedoutinaspecificwayasdescribedabove,itisrecommendedtousethe

“MOV”instructiontoaccesstheCCRAlowbyteregisters,namedCTMAL,usingthefollowing

accessprocedures.AccessingtheCCRAlowbyteregisterswithoutfollowingtheseaccess

procedureswillresultinunpredictablevalues.

Data

Bus

8-bit Buffer

CTMDH

CTMDL

CTMAH

CTMAL

CTM Counter Register

(Read only)

CTM CCRA Register

(Read/Write)

Thefollowingstepsshowthereadandwriteprocedures:

• WritingDatatoCCRA

♦

Step1.WritedatatoLowByteCTMAL

– notethatheredataisonlywrittentothe8-bitbuffer.

♦

Step2.WritedatatoHighByteCTMAH

– heredataiswrittendirectlytothehighbyteregistersandsimultaneouslydataislatched

fromthe8-bitbuffertotheLowByteregisters.

• ReadingDatafromtheCounterRegistersandCCRA

♦

Step1.ReaddatafromtheHighByteCTMDHorCTMAH

– heredataisreaddirectlyfromtheHighByteregistersandsimultaneouslydataislatched

fromtheLowByteregisterintothe8-bitbuffer.

♦

Step2.ReaddatafromtheLowByteCTMDLorCTMAL

– thisstepreadsdatafromthe8-bitbuffer.

HT45F56 Datasheet(PDF) 62 Page - Holtek Semiconductor Inc

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