Microchip Technology MA160014 Data Sheet

 2010-2012 Microchip Technology Inc.

DS41412F-page 303

17.2.10

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 (See TRIS register)

• Configure pin as analog

2.

Configure the ADC module:

• Select ADC conversion clock

• Configure voltage reference

• Select ADC input channel

• Select result format

• Select acquisition delay

• 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: Software delay required if ACQT bits are

set to zero delay. See 

;This code block configures the ADC

;for polling, Vdd and Vss as reference, Frc 

clock and AN0 input.

;

;Conversion start & polling for completion 

; are included.

;

MOVLW

B’10101111’

;right justify, Frc,

MOVWF

ADCON2

; & 12 TAD ACQ time

MOVLW

B’00000000’

;ADC ref = Vdd,Vss

MOVWF

ADCON1

;

BSF

TRISA,0

;Set RA0 to input

BSF

ANSEL,0

;Set RA0 to analog

MOVLW

B’00000001’

;AN0, ADC on

MOVWF

ADCON0

;

BSF

ADCON0,GO

;Start conversion

ADCPoll:

BTFSC

ADCON0,GO

;Is conversion done?

BRA

ADCPoll

;No, test again

; Result is complete - store 2 MSbits in

; RESULTHI and 8 LSbits in RESULTLO

MOVFF

ADRESH,RESULTHI

MOVFF

ADRESL,RESULTLO