各位大神，DS18B20读取温度，加上CRC校验后，温度值不正确,帮忙看看问题出在哪? -

#include "reg52.h"
#include "intrins.h"
#define uint unsigned int
#define uchar unsigned char
sbit _RD=P2^6;
sbit _WR=P2^5;
sbit _EN=P2^7;
sbit DQ=P3^7;
uchar code table[]={0x30,0x31,0x32,0x33,0x34,0x35,0x36,0x37,0x38,0x39};
uchar code CrcTable [256]={
0, 94, 188, 226, 97, 63, 221, 131, 194, 156, 126, 32, 163, 253, 31, 65,
157, 195, 33, 127, 252, 162, 64, 30, 95, 1, 227, 189, 62, 96, 130, 220,
35, 125, 159, 193, 66, 28, 254, 160, 225, 191, 93, 3, 128, 222, 60, 98,
190, 224, 2, 92, 223, 129, 99, 61, 124, 34, 192, 158, 29, 67, 161, 255,
70, 24, 250, 164, 39, 121, 155, 197, 132, 218, 56, 102, 229, 187, 89, 7,
219, 133, 103, 57, 186, 228, 6, 88, 25, 71, 165, 251, 120, 38, 196, 154,
101, 59, 217, 135, 4, 90, 184, 230, 167, 249, 27, 69, 198, 152, 122, 36,
248, 166, 68, 26, 153, 199, 37, 123, 58, 100, 134, 216, 91, 5, 231, 185,
140, 210, 48, 110, 237, 179, 81, 15, 78, 16, 242, 172, 47, 113, 147, 205,
17, 79, 173, 243, 112, 46, 204, 146, 211, 141, 111, 49, 178, 236, 14, 80,
175, 241, 19, 77, 206, 144, 114, 44, 109, 51, 209, 143, 12, 82, 176, 238,
50, 108, 142, 208, 83, 13, 239, 177, 240, 174, 76, 18, 145, 207, 45, 115,
202, 148, 118, 40, 171, 245, 23, 73, 8, 86, 180, 234, 105, 55, 213, 139,
87, 9, 235, 181, 54, 104, 138, 212, 149, 203, 41, 119, 244, 170, 72, 22,
233, 183, 85, 11, 136, 214, 52, 106, 43, 117, 151, 201, 74, 20, 246, 168,
116, 42, 200, 150, 21, 75, 169, 247, 182, 232, 10, 84, 215, 137, 107, 53};
uchar flag=0; //负显标志，为0时表示温度高于零度，为1时，表示温度低于0度
uchar *p;
uchar temp_buff[9]; //存储读取的字节，read scratchpad为9字节，read rom ID为8字节
uchar id_buff[8];
/**********************************************************************
函数功能：微秒级延时子函数
入口参数：设置延时时长
说明：12MHz晶振下，n为1时，延时约14us
时间：2019年08月09日
**********************************************************************/
void delayus(uint n)
{
while(--n);
}
/**********************************************************************
函数功能：毫秒级延时子函数
入口参数：设置延时时长
说明：12MHz晶振下，z为1时，延时约1ms
时间：2019年08月09日
**********************************************************************/
void delayms(uint z)
{
uint x,y;
for(x=z;x>0;x--)
for(y=122;y>0;y--);
}
//**************************************DS18B20驱动*****************************************************
void dsreset(void) //18B20复位，初始化函数
{
DQ=0;
delayus(100);
DQ=1;
delayus(20);
}
void Write_Byte(uchar com)
{
uchar i;
for(i=0;i<8;i++)
{
DQ=0;
DQ=com&0x01;
delayus(20);
DQ=1;
com>>=1;
}
}
uchar Read_Byte(void)
{
uchar i,dat=0;
DQ=1;
_nop_();
for(i=0;i<8;i++)
{
DQ=0;
dat>>=1;
DQ=1;
_nop_();
_nop_();
_nop_();
_nop_();
if(DQ)
dat|=0x80;
else
dat|=0x00;
delayus(80);
DQ=1;
}
return(dat);
}
void read_bytes(uchar j)
{
uchar i;
for(i=0;i<j;i++)
{
*p=Read_Byte();
p++;
}
}
uchar Temp_CRC(uchar j)
{
uchar i,crc=0;
for(i=0;i<j;i++)
crc=CrcTable[crc^temp_buff[i]];
return (crc);
}
void ReadID(void)
{
dsreset();
Write_Byte(0x33);
read_bytes(8);
}
uint Read_Temp()
{
uint temp;
read_bytes(9);
if(Temp_CRC(9)==0)
{
if(flag==1)
{
temp=(~temp)+1;
temp=temp*0.625+0.5;
}
else
temp=temp*0.625+0.5;
}
return temp;
}
void Config18b20() //重新配置报警限定值和分辨率
{
dsreset();
Write_Byte(0xcc);
Write_Byte(0x4e);
Write_Byte(0x19);
Write_Byte(0x1a);
Write_Byte(0x7f);
dsreset();
Write_Byte(0xcc);
Write_Byte(0x48);
dsreset();
Write_Byte(0xcc);
Write_Byte(0xb8);
}
uint Temp_value()
{
uint temp;
p=id_buff;
ReadID();
Config18b20();
dsreset();
Write_Byte(0xcc);
Write_Byte(0x44);
dsreset();
Write_Byte(0xcc);
Write_Byte(0xbe);
temp=Read_Temp();
return temp;
}
//**************************************液晶驱动*****************************************************
bit Busy()
{
bit busy;
_RD=0;
_WR=1;
_EN=1;
delayus(5);
busy=(bit)(P0&0x80);
_EN=0;
return busy;
}
void Wcmd(uchar com) //写命令
{
while(Busy()); //判忙
_RD=0;
_WR=0; //RD和WR为0时，在EN下降沿执行写指令码，在EN下降沿之前，要将指令送入P0
_EN=0;
delayus(5);
P0=com;
delayus(5);
_EN=1;
delayus(5);
_EN=0;
}
void Wdat(uchar dat) //写数据命令
{
while(Busy()); //判忙
_RD=1;
_WR=0; //RD为1，WR为0时，在EN下降沿执行写数据，在EN下降沿之前，要将数据送入P0
_EN=0;
delayus(5);
P0=dat;
delayus(5);
_EN=1;
delayus(5);
_EN=0;
}
void Lcd_Init() //液晶初始化
{
Wcmd(0x38);
Wcmd(0x0c);
Wcmd(0x06);
Wcmd(0x01);
}
void display0(uchar row,uchar line,uchar signal) //row为行位参数，line为列为参数
{
static uchar a=0;
if(row==1)
a=0x80;
if(row==2)
a=0xc0;
a=a+line-1;
Wcmd(a);
Wdat(signal);
}
void display1(uint temp,uchar hum)
{
uchar g1,g2,g3,g4,j0,j1,j2;
g1=temp/1000;
g2=temp%1000/100;
g3=temp%100/10;
g4=temp%10;
j0=hum/100;
j1=hum%100/10;
j2=hum%10;
display0(1,2,'T');
display0(1,3,'E');
display0(1,4,'M');
display0(1,5,'P');
display0(1,6,':');
if(flag==0)
display0(1,7,table[g1]); //不显示负
else
display0(1,7,'-'); //显示负
display0(1,8,table[g2]);
display0(1,9,table[g3]);
display0(1,10,'.');
display0(1,11,table[g4]);
display0(1,12,0xdf);
display0(1,13,0x43);
}
main()
{
Lcd_Init();
display0(1,1,0x20);
while(1)
{
display1(Temp_value(),100);
delayms(500);
}
}

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