ds18b20.c

这个是我设计的采用c8051f330为核心的测温系统源码

#include "ds18b20.h"
sbit DataPortDS1820=P1^3;
void Delay3us()
{
	_nop_();
	_nop_();
	_nop_();
}
void DelayNus(uchar us)
{
	while(us)
		{
			Delay3us();
			us--;
		}
}
void Delay45us()
{
	DelayNus(15);
}
void Delay30us()
{	
	DelayNus(10);
}
bit RstDS1820(void)
{
    uchar i;
    bit RstFlag;
	ENTER_CRITICAL
	RstFlag=1;	
	DataPortDS1820=0;
	for (i=0;i<40;i++)	//480us
		Delay45us(); 
	DataPortDS1820=1;
		Delay45us();
	if (DataPortDS1820==0) RstFlag=0;
	for (i=0;i<16;i++)	//240us
	{
		Delay45us();
	}
	OUT_CRITICAL
	return RstFlag;	
}

void WriteDS1820(uchar ch)
{
       uchar i;
	ENTER_CRITICAL
	DataPortDS1820=1;
	Delay3us();
	for (i=0;i<8;i++)
	{
		DataPortDS1820=0;
		Delay3us();
		DataPortDS1820=ch&0x01;
		Delay45us();Delay45us();
		DataPortDS1820=1;
		ch=ch>>1;
		Delay3us();
	}	
	OUT_CRITICAL
}
uchar ReadDS1820(void)
{
	uchar i,ch;
	ch=0;
	ENTER_CRITICAL
	DataPortDS1820=1;
	Delay3us();
	for (i=0;i<8;i++)
	{
		DataPortDS1820=0;
		Delay3us();
		DataPortDS1820=1;
		DelayNus(2);
		ch=ch>>1;
		if (DataPortDS1820==1)
		{
			ch=ch+0x80;
		}
		Delay45us();
	}	
	OUT_CRITICAL
	return ch;
}
void SkipROMCode(void)
{
	RstDS1820();
	WriteDS1820(0xcc); 
}
void StartADC(void)
{

	RstDS1820();		//复位
	WriteDS1820(0xcc);  //广播
	WriteDS1820(0x44); 	//启动AD转换 12bit700ms
}
uint GetTempValue(void)
{
	uint t;
	uchar a,b;
//    uchar i,j;
	StartADC();
	/*for(i=0;i<3;i++)
		for(j=0;j<250;j++)
 			Delay3us();*/
	SkipROMCode();
	WriteDS1820(0xBE);
	a=ReadDS1820();
	b=ReadDS1820();
	t=b;
	t=(t<<8)|a;
	return t;
}