以下绿色文字都是18B20的驱动程序的驱动程序，学习时不必每句都看懂，只需要知道每个函数的作用已利于以后调用！调用的方法在最后黑体字那里加以体会即可！
学习方法：
越是看似高级、复杂的器件，都会有自己的驱动程序往往由生产厂家提供！所以在后期提高阶段要联系如何使用这些驱动函数！就像是以后学习高一级的ARM系统时，那都是有自己的库函数的，使用时改变参数而已（当然从表面来讲）！后期价已熟练即可
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
};
//
void TempDelay (unsigned char idata us)
{
while(us--);
}
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;
}
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;
}
}
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);
}
void read_bytes (unsigned char idata j)
{
unsigned char idata i;
for(i="0;i<j;i++)
{
*p = ReadByte();
p++;
}
}
unsigned char CRC (unsigned char j)
{
unsigned char idata i,crc_data="0;
for(i="0;i<j;i++) //查表校验
crc_data = CrcTable[crc_data^temp_buff[i]];
return (crc_data);
}
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);
}
}
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 11 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
}
void ReadID (void)//读取器件 id
{
Init18b20();
WriteByte(0x33); //read rom
read_bytes(8);
}
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();
}
}
void T1zd(void) interrupt 3
{
TH1 = 0xD8; //10
TL1 = 0xF0;
TIM++;
}
#include <reg52.H>
#include "tem.H"
extern GetTemp(); //声明引用外部函数
extern unsigned int idata Temperature; // 声明引用外部变量
void delay(unsigned int i);
//else IO
sbit LS138A="P2^2; //管脚定义
sbit LS138B="P2^3;
sbit LS138C="P2^4;
//此表为 LED 的字模, 共阴数码管 0-9 -
unsigned char code Disp_Tab[] = {0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f,0x40};
unsigned long LedOut[5],LedNumVal;
void system_Ini()
{
TMOD|= 0x11;
TH1 = 0xD8; //10
TL1 = 0xF0;
IE = 0x8A;
TR1 = 1;
}
main()
{ unsigned char i;
system_Ini();
while(1)
{
GetTemp();
LedNumVal="Temperature; //把实际温度送到LedNumVal变量中
LedOut[0]=Disp_Tab[LedNumVal000/1000];
LedOut[1]=Disp_Tab[LedNumVal00/100];
LedOut[2]=Disp_Tab[LedNumVal0/10]; //十位
LedOut[3]=Disp_Tab[LedNumVal]; //个位
for(i="0;" i<4; i++)
{
P0 = LedOut[i] ;
switch(i)
{ //138译码
case 0:LS138A="0;" LS138B="0;" LS138C="0;" break;
case 1:LS138A="1;" LS138B="0;" LS138C="0;" break;
case 2:LS138A="0;" LS138B="1;" LS138C="0;" break;
case 3:LS138A="1;" LS138B="1;" LS138C="0;" break;
}
delay(100);
}
P0 = 0;
}
}
//延时程序
void delay(unsigned int i)
{
char j;
for(i; i > 0; i--)
for(j = 200; j > 0; j--);
}
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