麻烦大家帮咱看看程序呗~实在不知道哪有错误由运行不出正确结果~

这个设计是做八路数据采集再用LCD显示数据，但是AD输入端无论如何调节输出端就是显示5V，不知道是程序那里出了错误 ，求助大家帮忙改一下吧~~~
#include<reg52.h>
#include<intrins.h>
#define uchar unsigned char
#define uint unsigned int
sbit adoe=P3^7; //OE接3.7
sbit eoc=P3^3; //EOC接3.1
sbit adstart=P3^6; //start接3.2
sbit a0=P3^0; //A 3.3
sbit a1=P3^1; //B 3.4
sbit a2=P3^2; //C 3.5
sbit lcdrs=P3^5; //LCD RS 3.6
sbit lcden=P3^4; //LCD EN 3.7
sbit dula=P2^6;
sbit wela=P2^7;
long int advel,temp,b1,b2,b3,b4,b5;
uchar tt;
uchar code table[]="0123456789.V"; //显示电压
void delay(uint z) //延时
{
uint x,y;
for(x=z;x>0;x--)
for(y=100;y>0;y--);
}
void write_command(uchar com)//写命令
{
dula=0;
wela=0;
lcdrs=0; //输入指令
P0=com;
delay(5);
lcden=1; //读数据
delay(5);
lcden=0; //写指令或者数据
}
void write_data(uchar date)//写数据
{
lcdrs=1; //输入数据
P0=date; //显示
delay(5);
lcden=1; //读数据
delay(5);
lcden=0; //写指令或数据
}
void init()//初始化
{
lcden=0;
write_command(0x38);//不可变，显示模式设置：16*2显示，5*7点阵，8位数据接口
write_command(0x0c);//屏幕开启和光标闪烁
write_command(0x06);//显示开关及光标设置
write_command(0x01);//清屏
}
void start() //开始AD转换
{
adoe=0;
adstart=0;
_nop_();
adstart=1;
_nop_();
adstart=0;
advel=P0;

}
void xianshi() //AD转化结果显示
{
write_data(table[b1]); //最高位
delay(1); //
write_data(table[10]); // 小数点
delay(1); //
write_data(table[b2]); //第二位
delay(1); //
write_data(table[b3]); // 第三位
delay(1); //
write_data(table[11]); // 电压V
delay(1);
}
void first_mark() //0-4路通道的标号
{
write_command(0x01);
write_command(0x80);
write_data('A');
delay(1);
write_command(0x80+0x01);
write_data('=');
delay(1);
write_command(0x80+0x09);
write_data('B');
delay(1);
write_command(0x80+0x0a);
write_data('=');
delay(1);
write_command(0x80+0x40);
write_data('C');
delay(1);
write_command(0x80+0x41);
write_data('=');
delay(1);
delay(1);write_command(0x80+0x49);
write_data('D');
delay(1);
write_command(0x80+0x4a);
write_data('=');
delay(1);
}
void second_mark() //5-7路通道的标号
{
write_command(0x01);
write_command(0x80);
write_data('E');
delay(1);
write_command(0x80+0x01);
write_data('=');
delay(1);
write_command(0x80+0x09);
write_data('F');
delay(1);
write_command(0x80+0x0a);
write_data('=');
delay(1);
write_command(0x80+0x40);
write_data('G');
delay(1);
write_command(0x80+0x41);
write_data('=');
delay(1);
delay(1);write_command(0x80+0x49);
write_data('H');
delay(1);
write_command(0x80+0x4a);
write_data('=');
delay(1);
}
void main()
{
a2=0;
init(); //调用LCD初始化子程序
TMOD=0x01;
EA=1;//开总中断
TH0=(65535-1000)/256;
TL0=(65535-1000)%256;
ET0=1;//开定时器0中断
TR0=1;//定时器0置位
first_mark();
while(1)
{
a0=0; //0路或4路通道的AD转化
a1=0;
start();
while(!eoc);
adoe=1;
temp=P1;
delay(3);
adoe=0;
b1=(temp*500/255)/100; //最高位
b2=(temp*500/255)%100/10; //第二位
b3=(temp*500/255)%10; //第三位
write_command(0x80+0x02);
xianshi();
a0=1; //1路或5路通道的AD转化
a1=0;
start();
while(!eoc);
adoe=1;
temp=P1;
delay(3);
adoe=0;
b1=(temp*500/255)/100; //最高位
b2=(temp*500/255)%100/10; //第二位
b3=(temp*500/255)%10; //第三位
write_command(0x80+0x0b);
xianshi();
a0=0; //2路或6路通道的AD转化
a1=1;
start();
while(!eoc);
adoe=1;
temp=P1;
delay(3);
adoe=0;
b1=(temp*500/255)/100; //最高位
b2=(temp*500/255)%100/10; //第二位
b3=(temp*500/255)%10; //第三位
write_command(0x80+0x42);
xianshi();
a0=1; //3路或7路通道的AD转化
a1=1;
start();
while(!eoc);
adoe=1;
temp=P1;
delay(3);
adoe=0;
b1=(temp*500/255)/100; //最高位
b2=(temp*500/255)%100/10; //第二位
b3=(temp*500/255)%10; //第三位
write_command(0x80+0x4b);
xianshi();
}
}
void timer0() interrupt 1 //什么意思？
{
TH0=(65536-50000)/256;
TL0=(65536-50000)%256;
tt++;
if((a2==0&&tt==20)==1) //LCD第二屏显示
{

tt=0;
a2=1;
second_mark();
}
if((a2==1&&tt==20)==1) //LCD第一屏显示
{

tt=0;
a2=0;
first_mark();
}

}