DS18B20程序

#include

#include

#include "Delay.h"

sbit DS18b20_DataPort=P1^7; //引腳選擇

bit DS18b20_reset(void) //返回0-有設(shè)備連接1-無(wú)設(shè)備連接

{

unsigned char i;

bit RstFlag;

RstFlag=1;

DS18b20_DataPort=0;

delay_us(600);//器件反應(yīng)時(shí)間最少480us

DS18b20_DataPort=1;

delay_us(60); //15us-60us

for (i=0;i<16;i++) //60us-240us

{

delay_us(15);

if (DS18b20_DataPort==0)

RstFlag=0;

}

delay_us(240);// 低電平持續(xù)時(shí)間最少240us

return RstFlag;

}

void DS1820_write(unsigned char command)

{

unsigned char i;

DS18b20_DataPort=1;

delay_us(1);

for (i=0;i<8;i++)

{

EA=0;

DS18b20_DataPort=0;

delay_us(15);

DS18b20_DataPort=ch&0x1;

EA=1;

delay_us(50);

DS18b20_DataPort=1;

command=command>>1;

delay_us(1);

}

}

unsigned char DS1820_read(void)

{

unsigned char i,date = 0;

DS18b20_DataPort = 1;

delay_us(1);

for (i = 0;i < 8;i++)

{

EA = 0;

DS18b20_DataPort = 0;

delay_us(10);

DS18b20_DataPort = 1;

delay_us(2);

date = date>>1;

if (DS18b20_DataPort == 1)

{

date += 0x80;

}

EA = 1;

delay_us(50);

}

return date;

}

void DS1820_skipROM(void) //主機(jī)發(fā)送跳過(guò)讀序列號(hào)的操作指令

{

DS18b20_reset();

DS18b20_write(0xcc);

}

void DS1820_startADC(void)

{

DS18b20_reset(); //復(fù)位

DS18b20_write(0xcc); //廣播

DS18b20_write(0x44); //啟動(dòng)AD轉(zhuǎn)換 12bit700ms

}

unsigned int DS1820_getTempValue(void)

{

unsigned char i,j;

unsigned int T;

DS18b20_skipROM();

DS18b20_write(0xBE); //讀取溫度的命令

i=DS18b20_read();

j=DS18b20_read();

DS18b20_startADC();

T = i+j*256;

if (T==0xffff)

return 0xffff;

if (T>0x8000) //溫度為負(fù)號(hào)

{

T = -T;

return (0x8000+T*5/80); // 計(jì)算溫度的值

}

else //溫度為正值

return (T*5/80);

}

//主函數(shù)

void main(void)

{

int w;

Init();//系統(tǒng)初始化

while(1)

{

w = DS1820_getTempValue(); //將溫度值送出

_nop_;

_nop_;

_nop_;

}

//while(1);

}

//-------------------------------------------------------------

//程序結(jié)束

//---------------------------------