I am a very intermittent user of PICs.  Last time I did anything was years
ago when I made a battery voltage monitor using a PIC16C715, which has four
8-bit A/D ports on it.  I am now working on a project where I need more
resolution so I got a couple PIC16C733's to develop on because they have
12-bit A/D's.

This is the routine I used with the old 8-bit A/D to get my analog value:


;;;;;;; SUB - READ BATTERY VOLTAGE ;;;;;;;;;;;;;;;;;;;;;;;;;;;

R_BATTV
      movlw b'10000001' ; Configure A/D - select RA0.
      movwf adcon0
      call  D_20US      ; Delay 20 microseconds.
      bsf   adcon0,2    ; Start conversion.
      btfsc adcon0,2    ; Test go/done bit.
      goto  $-1
      movf  adres,w     ; Conv complete, get A/D result.
      movwf BATTV       ; Write data to register.
      return

My question regards grabbing a 12 bit A/D analog value.  Before it was just
grabbing one 8-bit number and copying it to a regular 8-bit register.
Forgive my ignorance on this, but do I now grab the upper 4 bits and place
value in one 8-bit register and the lower 8 bit value into a second 8-bit
register?

Thanks.

M Peterson

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