PIC16C71X
7.4
A/D Conversions
Note: The GO/DONE bit should NOT be set in
Example 7-2 shows how to perform an A/D conversion.
The RA pins are configured as analog inputs.The ana-
log reference (VREF) is the device VDD. The A/D inter-
rupt is enabled, and the A/D conversion clock is FRC.
The conversion is performed on the RA0 pin (channel
0).
the same instruction that turns on the A/D.
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 2TAD wait
is required before the next acquisition is started. After
this 2TAD wait, an acquisition is automatically started
on the selected channel.
EXAMPLE 7-2: A/D CONVERSION
BSF
CLRF
BCF
MOVLW
MOVWF
BSF
STATUS, RP0
ADCON1
STATUS, RP0
0xC1
ADCON0
INTCON, ADIE
INTCON, GIE
; Select Bank 1
; Configure A/D inputs
; Select Bank 0
; RC Clock, A/D is on, Channel 0 is selected
;
; Enable A/D Interrupt
; Enable all interrupts
BSF
;
;
;
;
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.
DS30272A-page 42
1997 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
