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Optimizing The St6 A/d Converter Accuracy

;******************** SUBROUTINE AVERAGE ***********************

;description: measures ADC input 256 times and stores average

*

;

of the 256 measures into accumulator

*

;***************************************************************

average

lid ior,10h

; global enable interrupts

clr aver_lo

;aver_lo, aver_hi and count are RAM registers

clr aver_hi

ldi count,255

; set for 256 measurements

aver1

ldi adcc,10110000b

; start conversion with interrupt

wait

ld a,adc

;======================= two byte addition of adc to 16-bit word:

add a, aver_lo

jrnc aver2

inc aver_hi

aver2 ld aver_lo,a

;======================= end of two byte addition

ld a,count

jrz aver4

dec count

jp aver1

;do it 256 times

aver4 ld a,aver_lo

cpi a,127

;round to next value if decimal part >0.5

jrc aver3

inc aver_hi

aver3 ld a, aver_hi ;store high byte of result into accumulator,

ret

;the low byte is not significant

;*********************** interrupt service routine *************

adcint

ldi adcc,10h

reti

;*********************** interrupt vector **********************

.org 0ff0h

jp adcint

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