ADC Test Code

void ADC_Init(void){
    //Configure Inputs
    TRISA |= 0x01;
    ANSEL |= 0x01;

    ADCON0 = (1<<0) | (0<<2); //Enable ADC and select channel 0
    ADCON1 = (0<<4) | (0<<5); //Set both references to PIC supply
    ADCON2 = (0<<0) | (7<<3) | (0<<7); //Use 20 acquisition cycles and FOsc/2, left justified
}

void ADC_StartConv(void){
    ADCON0 |= (1<<1);
}

unsigned int ADC_CheckConv(void){
    if(ADCON0 & 2) return 1;
    else return 0;
}

void ADC_WaitForConv(void){
    while(ADC_CheckConv());
}

unsigned char ADC_GetConv(void){
    return ADRESH;
}

void main(){
    ADC_Init();

    unsigned char Conv = 0;

    //Continuously convert!
    while(1){
        ADC_StartConv();
        ADC_WaitForConv();

        //Conv contains the converted value
        Conv = ADC_GetConv();
    }
}