STC8H单片机打印ADC采集电压输出为0

单片机小white。..
求。路。大 STC8H单片机打印ADC采集电压输出为0

#include "reg51.h"
#include "intrins.h"
#include 

#define FOSC            11059200UL
#define BRT             (65536 - FOSC / 115200 / 4)

sfr     AUXR        =   0x8e;

sfr     ADC_CONTR   =   0xbc;
sfr     ADC_RES     =   0xbd;
sfr     ADC_RESL    =   0xbe;
sfr     ADCCFG      =   0xde;

sfr     P_SW2   =   0xba;
#define ADCTIM  (*(unsigned char volatile xdata *)0xfea8)

sfr     P0M1    =   0x93;
sfr     P0M0    =   0x94;
sfr     P1M1    =   0x91;
sfr     P1M0    =   0x92;
sfr     P2M1    =   0x95;
sfr     P2M0    =   0x96;
sfr     P3M1    =   0xb1;
sfr     P3M0    =   0xb2;
sfr     P4M1    =   0xb3;
sfr     P4M0    =   0xb4;
sfr     P5M1    =   0xc9;
sfr     P5M0    =   0xca;

int *BGV;                                       //内部1.19V参考信号源值存放在idata中
                                                //idata的EFH地址存放高字节
                                          //idata的F0H地址存放低字节
                                                //电压单位为毫伏(mV)
bit busy;

void UartIsr() interrupt 4
{
    if (TI)
    {
        TI = 0;
        busy = 0;
    }
    if (RI)
    {
        RI = 0;
    }
}

void UartInit()
{
    SCON = 0x50;
    TMOD = 0x00;
    TL1 = BRT;
    TH1 = BRT >> 8;
    TR1 = 1;
    AUXR = 0x40;
    busy = 0;
}

void UartSend(char dat)
{
    while (busy);
    busy = 1;
    SBUF = dat;
}

void ADCInit()
{
    P_SW2 |= 0x80;
    ADCTIM = 0x3f;                              //设置ADC内部时序
    P_SW2 &= 0x7f;
        ADCTIM = 0X2a;
    
    ADCCFG = 0x00;                              //设置ADC时钟为系统时钟/2/16
    ADC_CONTR = 0x8f;                           //使能ADC模块,并选择第15通道
}

int ADCRead()
{
    int res;

    ADC_CONTR |= 0x40;                          //启动AD转换
    _nop_();
    _nop_();
    while (!(ADC_CONTR & 0x20));                //查询ADC完成标志
    ADC_CONTR &= ~0x20;                         //清完成标志
    res = (ADC_RES << 8) | ADC_RESL;            //读取ADC结果

    return res;
}

void ADC()
{
    int res;
    int vcc;
    int i;

    P0M0 = 0x00;
    P0M1 = 0x00;
    P1M0 = 0x00;
    P1M1 = 0x00;
    P2M0 = 0x00;
    P2M1 = 0x00;
    P3M0 = 0x00;
    P3M1 = 0x00;
    P4M0 = 0x00;
    P4M1 = 0x00;
    P5M0 = 0x00;
    P5M1 = 0x00;

    BGV = (int idata *)0xef;
    ADCInit();                                  //ADC初始化
    UartInit();                                 //串口初始化

    ES = 1;
    EA = 1;

 ADCRead();
  ADCRead();                                  //前两个数据建议丢弃

    res = 0;
    for (i=0; i<8; i++)
    {
        res += ADCRead();                       //读取8次数据
    }
    res >>= 3;                                  //取平均值

  //  vcc = (int)(1024L * *BGV / res);            //(10位ADC算法)计算VREF管脚电压,即电池电压
  vcc = (int)(4096L * *BGV / res);            //(12位ADC算法)计算VREF管脚电压,即电池电压
                                                //注意,此电压的单位为毫伏(mV)
    UartSend(vcc >> 8);                         //输出电压值到串口
    UartSend(vcc);


        
   
}



        
   
}

#include "reg51.h"
#include "intrins.h"
#include 
#include 


void main(){
    
    UartInit();
    ADC();
     
    
     while(1)
{

    printf("%d\r\n",res);
    
    
}

}

#ifndef     __ADC8H_H__
#define     __ADC8H_H__


UartInit();
ADC();
int res;

全局变量定义的res，实际上从来没被赋值过，当然是0.
adc函数里也有res，和全局的res同名，但函数里重新定义了res，所以这res和全局的res不是一个。
这个代码整体很乱，感觉像是几个例程拼成的，没有组合好。
其它就不说了，建议改一下main函数

void main(){
    int adcvalue;
    UartInit();
    ADC();
     
    
while(1)
{
   adcvalue = ADCRead();
    printf("%d\r\n",adcvalue);
    
    
}
 
}