ds18b20(c8051f340).c

Keil C开发。单总线温度传感器DS18B20的C8051F34x程序。系统时钟为12MHz

/////////////////////////////////////
//  Generated Initialization File  //
/////////////////////////////////////

#include "C8051F340.h"
#include "INTRINS.H"
#define uchar unsigned char
#define uint unsigned int

void Write_Byte(uchar a);
void Tx_date(uchar);
sbit DQ=P1^3;
uchar templ,temph;
uchar  ID[8]={0x28,0xf0,0xd8,0x6f,0x01,0x00,0x00,0xad};
//uchar	NewID[8];
void Delay(uint d)
{
while(d--);
}
/*Delay(1)=22/12us; Delay(18)=10us;没变化2，变化1us;Delay(108)=45us;{Delay(87)=45us,Delay(118)=60us;}for()语句大概6.17个周期
，不加前三个，Delay(1000)=500us;for(2000)=1s} 

实际Delay(1)=1.31us;Delay(2)=1.68;Delay(15)=6.44us;Delay(10)=4.61;Delay(18)=7.55;Delay(20)=8.2;Delay(30)=12us;Delay(87)=32.89us;Delay(118)=44.29us;Delay(160)=60us;Delay(1000)
=368.41us;Delay(1500)=552.16us;Delay(1360)=500us;
*/

void init(void)
{
	
	uchar i;            //60-240us来产生应答信号，主机收到应答脉冲后表明总线上有器件
	   bit DS_flag;
	   DS_flag = 1;
	   DQ = 1;
	   Delay(1);
	   DQ = 0;
       Delay(1360);    //延时480us-900us
       DQ = 1; //产生上升沿 
       Delay(90);//拉高总线33us，等待18B20响应
	   while(DQ);
	   while(~DQ);
	  
	   Delay(1000);  //360us
	Write_Byte(0x55);	//符合ROM
	for(i=0;i<8;i++)
	Write_Byte(ID[i]);
	 
}



void Write_Byte(uchar b)   //写字节数据 
{
     uchar j;
     DQ = 1;
     Delay(1);
     for(j=0;j<8;j++)
     {
         DQ = 0;
         Delay(20);		//delay 8us
         DQ = b&0x01;	
         Delay(160);	//60 us
         b= b>>1;
		 DQ = 1;
         Delay(1); 
      } 
}

uchar Read_Byte(void) //读取一个字节
{
      uchar i,b;
	  b = 0;
	  DQ = 1;
	  Delay(1);    //保持至少1us
	  for(i=0;i<8;i++)
	  {
         DQ = 0;
	     Delay(10); //延时4.5us
         DQ = 1;
         Delay(10);
		 b= b>>1;
	     if(DQ == 1) b = b+0x80;
	     Delay(160);//60us
      } 
     return b;
}



void Convert_temp(void)
{
	uint d;
	init();
	Write_Byte(0x44);// 启动温度转换
	for(d=2000;d>0;d--)
	Delay(1360);	//延时1s,大于转换时间750ms
}


void Get_temp(void)
	{	
		init();	// 初始化
		Write_Byte(0xbe);//读温度命令
		templ=Read_Byte();// 读取低位温度
		temph=Read_Byte();// 读取高位温度
		
	}

void Tx_date(uchar a)
{
	SBUF0=a;
	while(TI0==0);
	TI0=0;
}
void Read_id(uchar *a)
{
	uint i;
	init();
	Write_Byte(0x33);//读ROM
	for(i=0;i<8;i++)
	*a++=Read_Byte();
}
void main (void) 
{
	PCA0MD &= ~0x40;  
	OSCICN    = 0x83;
	XBR0     = 0x09;
    XBR1      = 0x40;
	SCON0     = 0x10;
    TCON      = 0x40;
    TMOD      = 0x21;
    CKCON     = 0x01;
    TL1       = 0x64;
    TH1       = 0x64;
//Read_id(NewID);


 while(1)
	{
		Convert_temp();
		Get_temp();
	//templ=0x128;
	//temph=0x01;
		Tx_date(templ);
		Tx_date(temph);
	}

}