I'll give that a shot Vasile, but it looks like what I'm already doing.


On 9/18/06, Vasile Surducan <piclist9@gmail.com> wrote:
>
> This is a jal procedure for reading the AD module of the 12F675. I
> think is self explanatory. Try to convert it in C and will (probably)
> work.
>
> const bit ref_extern    = high
> const bit ref_vdd       = low
> const bit left_justify  = high
> const bit right_justify = low
>
> procedure one_ch_ad_read ( byte in channel, bit in ref, bit in justify )
> is
> ; result in adresh and adresl,
> ; channel = 0...3, ref=high means external reference, justify=high
> means left justify
>    var byte local
>    if    channel == 0 then local = 0b_0000_0001
>    elsif channel == 1 then local = 0b_0000_0010
>    elsif channel == 2 then local = 0b_0000_0100
>    elsif channel == 3 then local = 0b_0000_1000
>    end if
>    asm bsf _rp0    ; set bank1
>    ansel = ( 0b_0001_0000 + local ) ; fosc/8, internal 4MHz clock
>    asm bcf _rp0    ; set bank0
>    channel = channel << 2
>    adcon0 = ( 0 + channel )
>   if ref then
>      asm bsf vcfg
>   else asm bcf vcfg
>   end if
>   if justify then
>       asm bcf adfm
>   else asm bsf adfm
>   end if
>
>    asm bsf adon                    ; supply the ad module
>    delay_10uS ( 1 )                ; wait the sampling time
>    asm bsf go_done                 ; start the conversion
>    while go_done loop end loop     ; wait for ad completion
> end procedure
>
> usage:
> one_ch_ad_read ( 0, ref_vdd, left_justify )
> read the adresh and adresl
>
>
> On 9/18/06, Shawn Wilton <black9@gmail.com> wrote:
> > Yeah, I have tried this and the conversion never returns.  I block on
> the
> > poll of the Go\Not Done bit and it never changes back to a zero
> indicating a
> > successful conversion.
> >
> >
> > On 9/18/06, Vasile Surducan <piclist9@gmail.com> wrote:
> > >
> > > There are two wais (at least) of using the AD module in PIC
> > > microcontrollers.
> > > First one is: set the AD channels and device operating frequency, turn
> > > on the AD module, wait 20uS for aquisition time and wait untill the
> > > GO/DONE bit is changing
> > --
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> >
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Shawn Wilton (b9 Systems)
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