Microchip Technology DM164130-2 Data Sheet

 2010-2012 Microchip Technology Inc.

DS41414D-page 167

16.3.2

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

4.

Wait the required acquisition time

.

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).

The global interrupt can be disabled if the
user is attempting to wake-up from Sleep
and resume in-line code execution.

Refer to 

;This code block configures the ADC
;for polling, Vdd and Vss references, Frc 
;clock and AN0 input.
;
;Conversion start & polling for completion 
; are included.
;
BANKSEL

ADCON1

;

MOVLW

B’11110000’ ;Right justify, Frc

;clock

MOVWF

ADCON1

;Vdd and Vss Vref

BANKSEL

TRISA

;

BSF

TRISA,0

;Set RA0 to input

BANKSEL

ANSEL

;

BSF

ANSEL,0

;Set RA0 to analog

BANKSEL

ADCON0

;

MOVLW

B’00000001’ ;Select channel AN0

MOVWF

ADCON0

;Turn ADC On

CALL

SampleTime

;Acquisiton delay

BSF

ADCON0,ADGO ;Start conversion

BTFSC

ADCON0,ADGO ;Is conversion done?

GOTO

$-1

;No, test again

BANKSEL

ADRESH

;

MOVF

ADRESH,W

;Read upper 2 bits

MOVWF

RESULTHI

;store in GPR space

BANKSEL

ADRESL

;

MOVF

ADRESL,W

;Read lower 8 bits

MOVWF

RESULTLO

;Store in GPR space