HT45F3W datasheet(111/167 Pages) HOLTEK

111 / 167 page

Rev. 1.50

110

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Rev. 1.50

111

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HT45F3W

R-Type Blood Pressure Meter Flash MCU

HT45F3W

R-Type Blood Pressure Meter Flash MCU

Thediagramshowstheidealtransferfunctionbetweentheanaloginputvalueandthedigitised

outputvaluefortheA/Dconverter.Exceptforthedigitisedzerovalue,thesubsequentdigitised

valueswillchangeatapoint0.5LSBbelowwheretheywouldchangewithouttheoffset,andthe

lastfullscaledigitisedvaluewillchangeatapoint1.5LSBbelowtheVDDorVREFlevel.

FF EH

(

)

A/ D C onv er si on

Re su lt

FFFH

FF DH

03H

02H

01H

0. 5 LS B

409 3 4094 4095 409 6

A nal og In pu t Vo lt age

1. 5 LS B

V DD o r V RE F

409 6

Ideal A/D Transfer Function

A/D Programming Example

ThefollowingtwoprogrammingexamplesillustratehowtosetupandimplementanA/D

conversion.Inthefirstexample,themethodofpollingtheEOCBbitintheADCRregisterisusedto

detectwhentheconversioncycleiscomplete,whereasinthesecondexample,theA/Dinterruptis

usedtodeterminewhentheconversioniscomplete.

Example: using an EOCB polling method to detect the end of conversion

clr ADE

; disable ADC interrupt

mov a, 01H

mov ACSR

; select fSYS/8 as A/D clock

clr ADOFF

mov a, 0FH

; setup ANCSR to configure pins AN0~AN3

mov ANCSR,a

mov a, 00H

; setup ADCR register to configure Port as A/D inputs

mov ADCR, a

; and select AN0 to be connected to the A/D converter

Start_conversion:

clr START

set START

; reset A/D

clr START

; start A/D

Polling_EOC:

sz EOCB

; poll the ADCR register EOCB bit to detect end

; of A/D conversion

jmp polling_EOC

; continue polling

mov a, ADRL

; read low byte conversion result value

mov adrl_buffer, a

; save result to user defined register

mov a, ADRH

; read high byte conversion result value

mov adrh_buffer, a

; save result to user defined register

jmp start_conversion

; start next A/D conversion

Note:TopowerofftheADC,itisnecessarytosetADOFFas“1”.

HT45F3W 데이터시트(PDF) 111 Page - Holtek Semiconductor Inc

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