PIC16F722A Datasheet, PDF (91/284 Pages) Microchip Technology – 28-Pin Flash Microcontrollers with nanoWatt XLP Technology

9.2.6 A/D CONVERSION PROCEDURE
This is an example procedure for using the ADC to
perform an Analog-to-Digital conversion:
1. Configure Port:
• Disable pin output driver (Refer to the TRIS
register)
• Configure pin as analog (Refer to the ANSEL
register)
2. Configure the ADC module:
• Select ADC conversion clock
• Configure voltage reference
• Select ADC input channel
• Turn on ADC module
3. Configure ADC interrupt (optional):
• Clear ADC interrupt flag
• Enable ADC interrupt
• Enable peripheral interrupt
• Enable global interrupt⁽¹⁾
4. Wait the required acquisition time⁽²⁾.
5. Start conversion by setting the GO/DONE bit.
6. Wait for ADC conversion to complete by one of
the following:
• Polling the GO/DONE bit
• Waiting for the ADC interrupt (interrupts
enabled)
7. Read ADC Result.
8. Clear the ADC interrupt flag (required if interrupt
is enabled).
Note 1: The global interrupt can be disabled if the
user is attempting to wake-up from Sleep
and resume in-line code execution.
2: Refer to Section 9.3 “A/D Acquisition
Requirements”.
PIC16F/LF722A/723A
EXAMPLE 9-1: A/D CONVERSION
;This code block configures the ADC
;for polling, Vdd reference, Frc clock
;and AN0 input.
;
;Conversion start & polling for completion
; are included.
;
BANKSEL ADCON1
;
MOVLW
B’01110000’ ;ADC Frc clock,
;VDD reference
MOVWF
ADCON1
;
BANKSEL TRISA
;
BSF
TRISA,0 ;Set RA0 to input
BANKSEL ANSELA
;
BSF
ANSELA,0 ;Set RA0 to analog
BANKSEL ADCON0
;
MOVLW
B’00000001’;AN0, On
MOVWF
ADCON0
;
CALL
SampleTime ;Acquisiton delay
BSF
ADCON0,GO ;Start conversion
BTFSC
ADCON0,GO ;Is conversion done?
GOTO
$-1
;No, test again
BANKSEL ADRES
;
MOVF
ADRES,W ;Read result
MOVWF
RESULT
;store in GPR space
 2010 Microchip Technology Inc.
DS41417A-page 91