Datasheet

PIC16C71X
DS30272A-page 42  1997 Microchip Technology Inc.
7.4 A/D Conversions
Example 7-2 shows how to perform an A/D conversion.
The RA pins are configured as analog inputs. The ana-
log reference (V
REF) is the device VDD. The A/D inter-
rupt is enabled, and the A/D conversion clock is F
RC.
The conversion is performed on the RA0 pin (channel
0).
Clearing the GO/DONE
bit during a conversion will
abort the current conversion. The ADRES register will
NOT be updated with the partially completed A/D con-
version sample. That is, the ADRES register will con-
tinue to contain the value of the last completed
conversion (or the last value written to the ADRES reg-
ister). After the A/D conversion is aborted, a 2T
AD wait
is required before the next acquisition is started. After
this 2T
AD wait, an acquisition is automatically started
on the selected channel.
Note: The GO/DONE bit should NOT be set in
the same instruction that turns on the A/D.
EXAMPLE 7-2: A/D CONVERSION
BSF STATUS, RP0 ; Select Bank 1
CLRF ADCON1 ; Configure A/D inputs
BCF STATUS, RP0 ; Select Bank 0
MOVLW 0xC1 ; RC Clock, A/D is on, Channel 0 is selected
MOVWF ADCON0 ;
BSF INTCON, ADIE ; Enable A/D Interrupt
BSF INTCON, GIE ; Enable all interrupts
;
; Ensure that the required sampling time for the selected input channel has elapsed.
; Then the conversion may be started.
;
BSF ADCON0, GO ; Start A/D Conversion
: ; The ADIF bit will be set and the GO/DONE bit
: ; is cleared upon completion of the A/D Conversion.