HT45F3W datasheet(109/167 Pages) HOLTEK

109 / 167 page

Rev. 1.50

108

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Rev. 1.50

109

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HT45F3W

R-Type Blood Pressure Meter Flash MCU

HT45F3W

R-Type Blood Pressure Meter Flash MCU

AN7isaninternalA/Dinputwhichisconnectedtothebatteryvoltagedetector.Whenthebattery

voltagedetectorisenabledtheA/Dcanbeusedtomeasurethebatteryvoltage.

VDD

10K

3.3K

To ADC AN7

Battery Voltage Detector

Summary of A/D Conversion Steps

ThefollowingsummarisestheindividualstepsthatshouldbeexecutedinordertoimplementanA/

Dconversionprocess.

• Step1

SelecttherequiredA/DconversionclockbycorrectlyprogrammingbitsADCK2~ADCK0inthe

ACSRregister.

• Step2

EnabletheA/DbyclearingtheADOFFbitintheADCRregistertozero.

• Step3

SelectwhichchannelistobeconnectedtotheinternalA/Dconverterbycorrectlyprogramming

theACS2~ACS0bitswhicharealsocontainedintheADCRregister.

• Step4

SelectwhichpinsaretobeusedasA/Dinputsandconfigurethembycorrectlyprogrammingthe

PCR3~PCR0bitsintheANCSRregister.

• Step5

Iftheinterruptsaretobeused,theinterruptcontrolregistersmustbecorrectlyconfiguredto

ensuretheA/Dconverterinterruptfunctionisactive.Themasterinterruptcontrolbit,EMI,and

theA/Dconverterinterruptbit,ADE,mustbothbesethightodothis.

• Step6

TheanalogtodigitalconversionprocesscannowbeinitialisedbysettingtheSTARTbitin

theADCRregisterfromlowtohighandthenlowagain.Notethatthisbitshouldhavebeen

originallyclearedtozero.

• Step7

Tocheckwhentheanalogtodigitalconversionprocessiscomplete,theEOCBbitintheADCR

registercanbepolled.Theconversionprocessiscompletewhenthisbitgoeslow.Whenthis

occurstheA/DdataregistersADRLandADRHcanbereadtoobtaintheconversionvalue.Asan

alternativemethod,iftheinterruptsareenabledandthestackisnotfull,theprogramcanwaitfor

anA/Dinterrupttooccur.

Note:Whencheckingfortheendoftheconversionprocess,ifthemethodofpollingtheEOCB

bitintheADCRregisterisused,theinterruptenablestepabovecanbeomitted.

HT45F3W Datasheet(PDF) 109 Page - Holtek Semiconductor Inc

HT45F3W Datasheet(HTML) 109 Page - Holtek Semiconductor Inc

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