DS18B20能直接测出环境温度吗？它的输出信号需要先经过AD转换后再送入单片机么？

不用经过AD，单片机只需通过一个I/O口就可以把DS18B20的数据读出来，主要是要编程。
把程序写给你吧。程序里面的数组数据是我自己接的数码管显示数字数据，你应用时注意改就好。DS与单片机的接口也能自己决定，不必和我一样。
//安装目录下的EXE文件打开后可在电脑上显示当前温度值
#include
#define uchar unsigned char
#define uint unsigned int
sbit DS=P1^0; //define interface
uint temp; // variable of temperature
uchar flag1; // sign of the result positive or negative
//sbit dula=P2^6;
//sbit wela=P2^7;
//unsigned char code table2[]={0x3f,0x30,0x5b,0x4f,0x66,0x6d,0x7d,
// 0x07,0x7f,0x67/*,0x77,0x7c,0x39,0x5e,0x79,0x71*/};
//unsigned char code table1[]={0xbf,0xb0,0xdb,0xcf,0xe6,0xed,0xfd,
// 0x87,0xff,0xe7};
//unsigned char code table2[]={0x40,0x5e,0x24,0x21,0x13,0x09,0x08,
// 0x63,0x00,0x03/*,0x77,0x7c,0x39,0x5e,0x79,0x71*/};
//unsigned char code table1[]={0xc0,0xde,0xa4,0xa1,0x93,0x89,0x88,
// 0xe7,0x8f,0x87};
unsigned char code table5[]={0x77,0x22,0x6d,0x5d,0x1e,0x5b,0x7b,
0x15,0x7f,0x1f};
unsigned char code table6[]={0xf7,0xa2,0xed,0xdd,0x9e,0xdb,0xfb,
0x95,0xff,0x9f};

void delay(uint count) //delay
{
uint i;
while(count)
{
i=200;
while(i>0)
i--;
count--;
}
}
///////功能:串口初始化,波特率9600，方式1///////
void Init_Com(void)
{
TMOD = 0x20;
PCON = 0x00;
SCON = 0x50;
TH1 = 0xFd;
TL1 = 0xFd;
TR1 = 1;
}

void dsreset(void) //send reset and initialization command 18B20复位，初始化函数
{
uint i;
DS=0;
i=103;
while(i>0)i--;
DS=1;
i=4;
while(i>0)i--;
}

bit tmpreadbit(void) //read a bit 读1位数据函数
{
uint i;
bit dat;
DS=0;i++; //i++ for delay
DS=1;i++;i++;
dat=DS;
i=8;while(i>0)i--;
return (dat);
}

uchar tmpread(void) //read a byte date 读1字节函数
{
uchar i,j,dat;
dat=0;
for(i=1;i<=8;i++)
{
j=tmpreadbit();
dat=(j<<7)|(dat>>1); //读出的数据最低位在最前面，这样刚好一个字节在DAT里
}
return(dat);
}

void tmpwritebyte(uchar dat) //write a byte to ds18b20 向1820写一个字节数据函数
{
uint i;
uchar j;
bit testb;
for(j=1;j<=8;j++)
{
testb=dat&0x01;
dat=dat>>1;
if(testb) //write 1
{
DS=0;
i++;i++;
DS=1;
i=8;while(i>0)i--;
}
else
{
DS=0; //write 0
i=8;while(i>0)i--;
DS=1;
i++;i++;
}

}
}

void tmpchange(void) //DS18B20 begin change 开始获取数据并转换
{
dsreset();
delay(1);
tmpwritebyte(0xcc); // address all drivers on bus 写跳过读ROM指令
tmpwritebyte(0x44); // initiates a single temperature conversion 写温度转换指令
}

uint tmp() //get the temperature 读取寄存器中存储的温度数据
{
float tt;
uchar a,b;
dsreset();
delay(1);
tmpwritebyte(0xcc);
tmpwritebyte(0xbe);
a=tmpread(); //读低8位
b=tmpread(); //读高8位
temp=b;
temp<<=8; //two byte compose a int variable 两个字节组合为1个字
temp=temp|a;
tt=temp*0.0625; //温度在寄存器中是12位，分辨率是0.0625
temp=tt*10+0.5; //乘10表示小数点后只取1位，加0.5是四折五入
return temp;
}

void readrom() //read the serial
{
uchar sn1,sn2;
dsreset();
delay(1);
tmpwritebyte(0x33);
sn1=tmpread();
sn2=tmpread();
}

void delay10ms() //delay
{
uchar a,b;
for(a=10;a>0;a--)
for(b=60;b>0;b--);
}

void display(uint temp) //显示程序
{
uchar A1,A2,A2t,A3,ser;
ser=temp/10;
SBUF=ser;
A1=temp/100;
A2t=temp%100;
A2=A2t/10;
A3=A2t%10;
//dula=0;
d4=0;
P0=table5[A1];
delay(1);
d4=1; //显示百位
//dula=1;
// dula=0;

/*wela=0;
P0=0x7e;
wela=1;
wela=0; */

//dula=0;
d3=0;
P0=table6[A2];
delay(1);
d3=1; //显示十位
//dula=1;
//dula=0;

/*wela=0;
P0=0x7d;
wela=1;
wela=0; */

d2=0;
P0=table5[A3];
delay(1);
d2=1; //显示个位
//dula=1;
//dula=0;

/*P0=0x7b;
wela=1;
wela=0; */

}

void main()
{
uchar a;
Init_Com();
do
{
tmpchange();
// delay(200);
for(a=1;a>0;a--)
{ display(tmp());
}
} while(1);
}
//安装目录下的EXE文件打开后可在电脑上显示当前温度值
#include
#define uchar unsigned char
#define uint unsigned int
sbit DS=P1^0; //define interface
uint temp; // variable of temperature
uchar flag1; // sign of the result positive or negative
//sbit dula=P2^6;
//sbit wela=P2^7;
//unsigned char code table2[]={0x3f,0x30,0x5b,0x4f,0x66,0x6d,0x7d,
// 0x07,0x7f,0x67/*,0x77,0x7c,0x39,0x5e,0x79,0x71*/};
//unsigned char code table1[]={0xbf,0xb0,0xdb,0xcf,0xe6,0xed,0xfd,
// 0x87,0xff,0xe7};
//unsigned char code table2[]={0x40,0x5e,0x24,0x21,0x13,0x09,0x08,
// 0x63,0x00,0x03/*,0x77,0x7c,0x39,0x5e,0x79,0x71*/};
//unsigned char code table1[]={0xc0,0xde,0xa4,0xa1,0x93,0x89,0x88,
// 0xe7,0x8f,0x87};
unsigned char code table5[]={0x77,0x22,0x6d,0x5d,0x1e,0x5b,0x7b,
0x15,0x7f,0x1f};
unsigned char code table6[]={0xf7,0xa2,0xed,0xdd,0x9e,0xdb,0xfb,
0x95,0xff,0x9f};

void delay(uint count) //delay
{
uint i;
while(count)
{
i=200;
while(i>0)
i--;
count--;
}
}
///////功能:串口初始化,波特率9600，方式1///////
void Init_Com(void)
{
TMOD = 0x20;
PCON = 0x00;
SCON = 0x50;
TH1 = 0xFd;
TL1 = 0xFd;
TR1 = 1;
}

void dsreset(void) //send reset and initialization command 18B20复位，初始化函数
{
uint i;
DS=0;
i=103;
while(i>0)i--;
DS=1;
i=4;
while(i>0)i--;
}

bit tmpreadbit(void) //read a bit 读1位数据函数
{
uint i;
bit dat;
DS=0;i++; //i++ for delay
DS=1;i++;i++;
dat=DS;
i=8;while(i>0)i--;
return (dat);
}

uchar tmpread(void) //read a byte date 读1字节函数
{
uchar i,j,dat;
dat=0;
for(i=1;i<=8;i++)
{
j=tmpreadbit();
dat=(j<<7)|(dat>>1); //读出的数据最低位在最前面，这样刚好一个字节在DAT里
}
return(dat);
}

void tmpwritebyte(uchar dat) //write a byte to ds18b20 向1820写一个字节数据函数
{
uint i;
uchar j;
bit testb;
for(j=1;j<=8;j++)
{
testb=dat&0x01;
dat=dat>>1;
if(testb) //write 1
{
DS=0;
i++;i++;
DS=1;
i=8;while(i>0)i--;
}
else
{
DS=0; //write 0
i=8;while(i>0)i--;
DS=1;
i++;i++;
}

}
}

void tmpchange(void) //DS18B20 begin change 开始获取数据并转换
{
dsreset();
delay(1);
tmpwritebyte(0xcc); // address all drivers on bus 写跳过读ROM指令
tmpwritebyte(0x44); // initiates a single temperature conversion 写温度转换指令
}

uint tmp() //get the temperature 读取寄存器中存储的温度数据
{
float tt;
uchar a,b;
dsreset();
delay(1);
tmpwritebyte(0xcc);
tmpwritebyte(0xbe);
a=tmpread(); //读低8位
b=tmpread(); //读高8位
temp=b;
temp<<=8; //two byte compose a int variable 两个字节组合为1个字
temp=temp|a;
tt=temp*0.0625; //温度在寄存器中是12位，分辨率是0.0625
temp=tt*10+0.5; //乘10表示小数点后只取1位，加0.5是四折五入
return temp;
}

void readrom() //read the serial
{
uchar sn1,sn2;
dsreset();
delay(1);
tmpwritebyte(0x33);
sn1=tmpread();
sn2=tmpread();
}

void delay10ms() //delay
{
uchar a,b;
for(a=10;a>0;a--)
for(b=60;b>0;b--);
}

void display(uint temp) //显示程序
{
uchar A1,A2,A2t,A3,ser;
ser=temp/10;
SBUF=ser;
A1=temp/100;
A2t=temp%100;
A2=A2t/10;
A3=A2t%10;
//dula=0;
d4=0;
P0=table5[A1];
delay(1);
d4=1; //显示百位
//dula=1;
// dula=0;

/*wela=0;
P0=0x7e;
wela=1;
wela=0; */

//dula=0;
d3=0;
P0=table6[A2];
delay(1);
d3=1; //显示十位
//dula=1;
//dula=0;

/*wela=0;
P0=0x7d;
wela=1;
wela=0; */

d2=0;
P0=table5[A3];
delay(1);
d2=1; //显示个位
//dula=1;
//dula=0;

/*P0=0x7b;
wela=1;
wela=0; */

}

void main()
{
uchar a;
Init_Com();
do
{
tmpchange();
// delay(200);
for(a=1;a>0;a--)
{ display(tmp());
}
} while(1);
}

能，不用ad的

靠 这哥们刷屏啊 赶紧的给分