HT45F65 datasheet(145/231 Pages) HOLTEK

145 / 231 page

Rev. 1.60

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Rev. 1.60

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HT45F65/HT45F66/HT45F67

Glucose Meter 8-Bit Flash MCU

Summary of A/D Conversion Steps

ThefollowingsummarisestheindividualstepsthatshouldbeexecutedinordertoimplementanA/D

conversionprocess.

• Step1

SelecttherequiredA/DconversionclockbycorrectlyprogrammingbitsADCK2~ADCK0inthe

ADCR1register.

• Step2

EnabletheA/DbyclearingtheADOFFbitintheADCR0registertozero.

• Step3

SelectwhichchannelistobeconnectedtotheinternalA/Dconverterbycorrectlyprogramming

theACS2~ACS0bitswhicharealsocontainedintheADCR0register.

• Step4

SelectwhichpinsaretobeusedasA/DinputsandconfigurerelatedI/Oregister.

• Step5

SelectpositiveandnegativereferencevoltageatVRPS[1:0]andVRNS[1:0]bitsforADC

referencevoltage.

• Step6

Iftheinterruptsaretobeused,theinterruptcontrolregistersmustbecorrectlyconfiguredto

ensuretheA/Dconverterinterruptfunctionisactive.Themasterinterruptcontrolbit,EMI,and

theA/Dconverterinterruptbit,ADE,mustbothbesethightodothis.

• Step7

TheanalogtodigitalconversionprocesscannowbeinitialisedbysettingtheSTARTbitin

theADCR0registerfromlowtohighandthenlowagain.Notethatthisbitshouldhavebeen

originallyclearedtozero.

• Step8

Tocheckwhentheanalogtodigitalconversionprocessiscomplete,theEOCBbitintheADCR0

registercanbepolled.Theconversionprocessiscompletewhenthisbitgoeslow.Whenthis

occurstheA/DdataregistersADRLandADRHcanbereadtoobtaintheconversionvalue.Asan

alternativemethod,iftheinterruptsareenabledandthestackisnotfull,theprogramcanwaitfor

anA/Dinterrupttooccur.

Note:Whencheckingfortheendoftheconversionprocess,ifthemethodofpollingtheEOCBbit

intheADCR0registerisused,theinterruptenablestepabovecanbeomitted.

Theaccompanyingdiagramshowsgraphicallythevariousstagesinvolvedinananalogtodigital

conversionprocessanditsassociatedtiming.AfteranA/Dconversionprocesshasbeeninitiated

bytheapplicationprogram,themicrocontrollerinternalhardwarewillbegintocarryoutthe

conversion,duringwhichtimetheprogramcancontinuewithotherfunctions.Thetimetakenforthe

A/Dconversionis16tADwheretADisequaltotheA/Dclockperiod.

HT45F65 Datasheet(PDF) 145 Page - Holtek Semiconductor Inc

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