What chip(s) would you use if you were to do this project again? I
understand the 4 bit noise... I planned on that. I am using a low tempo cap
(50ppm), did you do so also? I would hope the internal current sources are
not that temp-dependant!

Thanks a bunch,

Terry


At 05:46 PM 10/21/99 +0200, you wrote:
>Hej Terry A. Steen. Tack fšr ditt meddelande 11:17 1999-10-21 -0400 enligt
nedan:
>>Hi, new guy here...
>
>Welcome :)
>
>>I am trying to read the A/D port on a PIC14000. I am clocking at 16MHz XTAL
>>(want to try 20), going for 16bits.
>
>16 bit true resolution is completely impossible.
>I had almost 4*bit* noise before digital filter, so i was getting about
12bit real output.
>
>Also, it is drifting with temeprature, so it do need the calibration
algorithms described in the manual.
>
>>  I am REAL unsure of the proper way to
>>use the A/D input. I have followed the steps in the manual, but just don't
>>seem to be getting anywhere. Does anybody have a skeleton of a simple --
>>read AN0, so I can get this puppy rolling?
>>
>>Thanks!
>>
>>Terry 
>
>I found this in my first and never-again PIC14000 project
>think i cut-pasted it from a Micrichip demo code
>
>         bcf     STATUS,RP0      ;BANK0
>         clrf    ADTMRH          ;clear a/d timer for 16 bits
>         clrf    ADTMRL
>         bcf     PIR1,OVFIF      ;clear a/d timer overflow flag
>         bcf     PIR1,ADCIF      ;clear a/d capture complete flag
>         movlw   .50             ;500uS delay for signal to settle
>         call    delay10
>
>         bsf     STATUS,RP0      ;BANK1
>;       bsf     PIE1,ADCIE      ;** enable a/d capture interrupt
>         bsf     PIE1,OVFIE      ;## enable a/d timer overflow interrupt
>         bsf     INTCON,PEIE     ;enable peripheral interrupt
>         bcf     SLPCON,OSCOFF   ;leave main osc running during sleep for a/d
>         bcf     STATUS,RP0      ;BANK0
>
>         bcf     ADCON0,ADRST    ;start conversion
>
>         sleep                   ;can sleep instead of next ad_wait loop
>
>;ad_wait:
>;       LEDSINC
>;       btfss   PIR1,ADCIF      ;** wait until a/d capture
>;       btfss   PIR1,OVFIF      ;## wait until a/d timer overflows
>;       goto    ad_wait
>
>ad_stop:bsf     ADCON0,ADRST    ;stop a/d
>         btfsc   PIR1,ADCIF      ;## check if signal is greater than full
scale
>;       btfss   PIR1,OVFIF      ;** check is signal is greater than full
scale
>         goto    ad_ok
>         movlw   0xff            ;if signal is too large, value = ffff
>         movwf   ADCAPH
>         movwf   ADCAPL
>ad_ok:  
>         bcf     PIR1,OVFIF      ;clear a/d timer overflow flag
>         bcf     PIR1,ADCIF      ;clear a/d capture complete flag
>         return
>
>
>Good luck
>/Morgan
>Morgans Reglerteknik, HŠllekŒs, 277 35 KIVIK, SWEDEN
>   tel +46(0)414-446620, fax -70331,   mrt@iname.com
>
>