Microchip Technology AC164112 Data Sheet

© 2009 Microchip Technology Inc.

DS41341E-page 103

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

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).

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

;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,

;V

DD

 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