基于51单片机及DS18B20的温度上下限报警系统 原理图和原程序，发到邮箱852432575@qq.com。谢谢

/*************************此部分为18B20的驱动程序*************************************/
#include #include
sbit D18B20=P3^7;
#define NOP() _nop_() /* 定义空指令 */
#define _Nop() _nop_() /*定义空指令*/

void TempDelay (unsigned char idata us);
void Init18b20 (void);
void WriteByte (unsigned char idata wr); //单字节写入
void read_bytes (unsigned char idata j);
unsigned char CRC (unsigned char j);
void GemTemp (void);
void Config18b20 (void);
void ReadID (void);
void TemperatuerResult(void);

bit flag;
unsigned int idata Temperature;
unsigned char idata temp_buff[9]; //存储读取的字节，read scratchpad为9字节，read rom ID为8字节
unsigned char idata id_buff[8];
unsigned char idata *p,TIM;
unsigned char idata crc_data;

unsigned char 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};
//
/************************************************************
*Function:延时处理
*parameter:
*Return:
*Modify:
*************************************************************/
void TempDelay (unsigned char idata us)
{
while(us--);
}

/************************************************************
*Function:18B20初始化
*parameter:
*Return:
*Modify:
*************************************************************/
void Init18b20 (void)
{
D18B20=1;
_nop_();
D18B20=0;
TempDelay(80); //delay 530 uS//80
_nop_();
D18B20=1;
TempDelay(14); //delay 100 uS//14
_nop_();
_nop_();
_nop_();

if(D18B20==0)
flag = 1; //detect 1820 success!
else
flag = 0; //detect 1820 fail!
TempDelay(20); //20
_nop_();
_nop_();
D18B20 = 1;
}

/************************************************************
*Function:向18B20写入一个字节
*parameter:
*Return:
*Modify:
*************************************************************/
void WriteByte (unsigned char idata wr) //单字节写入
{
unsigned char idata i;
for (i=0;i<8;i++)
{
D18B20 = 0;
_nop_();
D18B20=wr&0x01;
TempDelay(3); //delay 45 uS //5
_nop_();
_nop_();
D18B20=1;
wr >>= 1;
}
}

/************************************************************
*Function:读18B20的一个字节
*parameter:
*Return:
*Modify:
*************************************************************/
unsigned char ReadByte (void) //读取单字节
{
unsigned char idata i,u=0;
for(i=0;i<8;i++)
{
D18B20 = 0;
u >>= 1;
D18B20 = 1;
if(D18B20==1)
u |= 0x80;
TempDelay (2);
_nop_();
}
return(u);
}

/************************************************************
*Function:读18B20
*parameter:
*Return:
*Modify:
*************************************************************/
void read_bytes (unsigned char idata j)
{
unsigned char idata i;
for(i=0;i {
*p = ReadByte();
p++;
}
}

/************************************************************
*Function:CRC校验
*parameter:
*Return:
*Modify:
*************************************************************/
unsigned char CRC (unsigned char j)
{
unsigned char idata i,crc_data=0;
for(i=0;i crc_data = CrcTable[crc_data^temp_buff[i]];
return (crc_data);
}

/************************************************************
*Function:读取温度
*parameter:
*Return:
*Modify:
*************************************************************/
void GemTemp (void)
{
read_bytes (9);
if (CRC(9)==0) //校验正确
{
Temperature = temp_buff[1]*0x100 + temp_buff[0];
// Temperature *= 0.625;
Temperature /= 16;
TempDelay(1);
}
}

/************************************************************
*Function:内部配置
*parameter:
*Return:
*Modify:
*************************************************************/
void Config18b20 (void) //重新配置报警限定值和分辨率
{
Init18b20();
WriteByte(0xcc); //skip rom
WriteByte(0x4e); //write scratchpad
WriteByte(0x19); //上限
WriteByte(0x1a); //下限
WriteByte(0x7f); //set 12 bit (0.125)
Init18b20();
WriteByte(0xcc); //skip rom
WriteByte(0x48); //保存设定值
Init18b20();
WriteByte(0xcc); //skip rom
WriteByte(0xb8); //回调设定值
}

/************************************************************
*Function:读18B20ID
*parameter:
*Return:
*Modify:
*************************************************************/
void ReadID (void)//读取器件 id
{
Init18b20();
WriteByte(0x33); //read rom
read_bytes(8);
}

/************************************************************
*Function:18B20ID全处理
*parameter:
*Return:
*Modify:
*************************************************************/
void TemperatuerResult(void)
{
p = id_buff;
ReadID();
Config18b20();
Init18b20 ();
WriteByte(0xcc); //skip rom
WriteByte(0x44); //Temperature convert

Init18b20 ();
WriteByte(0xcc); //skip rom
WriteByte(0xbe); //read Temperature
p = temp_buff;
GemTemp();
}

void GetTemp()
{
if(TIM==100) //每隔 1000ms 读取温度
{ TIM=0;
TemperatuerResult();
}

}
/*************************************
[ t1 (10ms)中断] 中断
*************************************/
void T1zd(void) interrupt 3
{
TH1 = 0xD8; //10
TL1 = 0xF0;
TIM++;

}
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