how to combine ADRESH and ADRESL on 12 bit ADC

Question

MICRO: PIC18LF47K42 compiler: XC8 application: MPLABX

Hi, im trying to combine the values in my 12 bit ADC. they go into ADRESH and ADRESL. my ADC is set up for right-justify which does formating as so: ADRESH:(----MSB,x,x,x) ADRESL: (X,X,X,X,X,X,X,LSB)

It's my first tiem ever working with an ADC and admitably i dont know very muc habout them. But from inspecting the value in my result register i can tell i dont have a great resolution. Im pretty sure its becasue of how im combining ADRESH and ADRESL. how could i do this? again its a 12Bit ADC. its being tested wit han LDR, when theres no light i get 0, whic his fine but when theres slight light it goes t oa decimal value of 48, so i increase the brightness slightly again and it stays at 48. until a large jump to whic hit jumps to 64 or something.

    #include "myIncludes.h"
volatile unsigned char ZCDSoftwareFlag = 0;
volatile unsigned char switchValue = 0;
void main(void) 
{
   
    portInit(); 
    triac = 0;
    unsigned char result;
    adcInit();                 
    while(1)
    {
      
        
        __delay_us(4);
        ADCON0bits.GO = 1; //Start conversion
        while (ADCON0bits.GO); //Wait for conversion done
        
        result = ADRESH;
        
        result = result << 8;
        result = result |ADRESL;
        
        
    }
}

And heres the ADC init function

void adcInit(void)
{
    ADCON0bits.FM = 1;              //right-justify 
    ADCON0bits.CS = 1;              //ADCRC Clock
    ADPCH = 0x00;                   //RA0 is Analog channel
    ADCON0bits.ON = 1;              //Turn ADC On
    ADCON0bits.GO = 1;              //Start conversion
}

Answer 1

You try to put an 12Bit result in a 8 Bit variable. Switch it to 16Bit.

uint16_t result;