Hello,

Have a question about the A/D on the 16f877. I gave my first shot on coding a
simple converter that uses a divider from a pot as an input to one of the
pins. Now I'm pretty sure I have my code set right, because when I read the
results (I did about 5 test cases), they all seem pretty accurate, except with
a few problems.

Some of the pins had constantly a constantly changing voltage that was
registering on my DMM. Most of the pins would be stable, either ~0 or 5.2V,
but some of them, each on different tests, would be fluctuating, sometimes
from 2.5-2.9V, and sometimes other values. Is this normal? Does the fact that
my program keeps going in a loop affect this (even though I'm reading the Go/!
Done flag to check when it's done)? And it seems to be different pins each
time, so there doesn't appear to be a definite pattern. On some readings, all
the pins are perfect. Any ideas?

Thank you,

Jai

PS: Just in case, I have my Code below.

clrf TRISB                 ;Set all of Port B and D to outputs
clrf TRISD

movlw 0xff
movwf TRISA

movlw 0x0E           ;Set Justification and set RA0 as the only analog input
movwf ADCON1


bcf STATUS, RP0         ;Switch back to Bank 0

movlw 0xC1           ;Select A/D on, Channel 0 and RC Clock
movwf ADCON0

movlw 0x00
movwf PORTB    ;initialize the ports to a blank value.
movwf PORTD

Start1


bsf ADCON0, GO           ;Start the A/D.
Loop1
btfsc ADCON0, GO
goto Loop1

;Finished The A/D conversion

movf ADRESL, 0     ;Move the low byte into Port B (B<7>:B<6>)
movwf PORTB

movf ADRESH, 0     ;Move the high byte into Port D (D<7>:D<0>)
movwf PORTD


goto Start1   ;Start it all over again.





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