#include <htc.h>
#include <pic18f45j10.h>
#define uint unsigned int
#define uchar unsigned char
#define PORTDIT(adr,bit)((unsigned)(&adr)*8+(bit))
static volatile int table[10]={0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90};
uchar ad_hdate,ad_ldate;
uint ad;
void delay(int a)  //延时
{
    long int i,j;
    for(j=0;j<a;j++)
    for(i=0;i<121;i++);
}
void main()
{
    //TRISA0=1;
    INTCON=0X00;
    TRISC=0X00;
    TRISB=0X00;
     PORTB=0x00;
    PORTC=0x00;
    ADCON1=0X00;
    ADCON0=0X42;
    ADCON2=0X93;
    ADON=1;
    while(GODONE);
    ADON=0;
    ad_hdate=ADRESH;
    ad_ldate=ADRESL;
    ad=ad_ldate+ad_hdate*256;
    while(1)
    {
        PORTC=table[ad/100];
        PORTB=0X01;
        delay(10);
        PORTB=0X00;
        PORTC=table[ad/10%10];
        PORTB=0X02;
        delay(10);
        PORTB=0X00;
        PORTC=table[ad%10];
        PORTB=0X04;
        delay(10);
        PORTB=0X00;
    }

    
    
}
这是我用过的，不过没有转成电压，就是显示ad的数值，或许能给你点帮助