Sample program to test ADC of PIC16F877A

ADC_example.c

//ADC example program written for PIC programming tutorial.
//Target Device PIC16F877A
//Compiler: XC8
//Author  : Anil C S
//Website : www.technoburst.net 
//Email   : anil@technoburst.net , technoburst@gmail.com

#include <stdio.h>
#include <stdlib.h>

#define _XTAL_FREQ 20000000     //defining crystal frequency to 20 MHz

// PIC16F877A Configuration Bit Settings

#include <xc.h>

// CONFIG
#pragma config FOSC = HS        // Oscillator Selection bits (HS oscillator)
#pragma config WDTE = OFF       // Watchdog Timer Enable bit (WDT disabled)
#pragma config PWRTE = OFF      // Power-up Timer Enable bit (PWRT disabled)
#pragma config BOREN = ON       // Brown-out Reset Enable bit (BOR enabled)
#pragma config LVP = OFF        // Low-Voltage (Single-Supply) In-Circuit Serial Programming Enable bit (RB3 is digital I/O, HV on MCLR must be used for programming)
#pragma config CPD = OFF        // Data EEPROM Memory Code Protection bit (Data EEPROM code protection off)
#pragma config WRT = OFF        // Flash Program Memory Write Enable bits (Write protection off; all program memory may be written to by EECON control)
#pragma config CP = OFF         // Flash Program Memory Code Protection bit (Code protection off)


void main()
{
    unsigned short ADCResult;

    TRISD = 0b00000000;     //Setting PORTD as output port
    PORTD = 0b00000000;     //Initializing PORTD

    ADCON0bits.ADCS  = 0;   //Selecting the clk division factor = FOSC/2
    ADCON1bits.ADCS2 = 0;   //Selecting the clk division factor = FOSC/2

    ADCON1bits.ADFM = 1;    //Result right justified

    ADCON1bits.PCFG = 0;    //Setting all the analog ports as Analog inputs

    ADCON0bits.ADON = 1;    //Turns on ADC module

    ADCON0bits.CHS = 0;     //Selects channel 0 ( AN0 )

    while(1)
    {
    __delay_us(25); //Waits for the acquisition to complete

    ADCON0bits.GO = 1;   //Starts ADC conversion

    while (ADCON0bits.nDONE) continue;   //wait till ADC conversion is over

    ADCResult = (ADRESH<<8) + ADRESL ;   //Merging the MSB and LSB

    if(ADCResult>512)
        PORTD = 255;
    else
        PORTD = 0;
    }
}