ds18b20温度测量.c

这是本人花了200元买的51开发板上的所有程序资料

//MCU: AT89S51
//晶振：12M
#include "AT89X51.h"
#include "intrins.h"
//common part 
#define  HIGH     1
#define  LOW      0
#define  TRUE     1
#define  ZERO     0 
#define  MSB      0x80
//ds18b20 part
#define  SkipRom              0xcc
#define  ConvertTemperature   0x44
#define  ReadScratchpad       0xbe

/*******************************************************************/
sbit One_Wire_Bus=P2^7;

unsigned char code numcode[]={0xc0,0xf9,0xa4,0xb0,0x99,
                              0x92,0x82,0xf8,0x80,0x90,
							  0x86,0x8c,0xb7,0X9C,0XC6
							  };//数字0～9及"EP=OC"共阳数码管代码 
unsigned char code dot_numcode[]={0X40,0X79,0X24,0X30,0X19,
                                  0X12,0X02,0X78,0X00,0X10
								 };//带数点的0～9共阳数码管代码
unsigned char code bitcode[]={0xfe,0xfd,0xfb,0xf7,
                              0xef,0xdf,0xbf,0x7f}; //数码管位选代码
unsigned char dispbuff[8]={14,13,0,0,0,12,11,10};
unsigned char timecount;
unsigned char disp_bit_count;

/********************************************************************/
unsigned char GetScratchpad[2];
unsigned char code decimalH[16]={00,06,12,18,25,31,37,43,50,56,62,68,75,81,87,93};
unsigned char code decimalL[16]={00,25,50,75,00,25,50,75,00,25,50,75,00,25,50,75};
unsigned char ResultTemperatureH;
unsigned char ResultTemperatureLH,ResultTemperatureLL;
unsigned char ResultSignal;

/********************************************************************/
void One_Wire_Delay(unsigned char delay_time)
{ 
 while(delay_time)delay_time--;//延时时间:=(8+delay_time*6)us;
}

//*****初始化DS18B20******/
void Initize_One_Wire_Bus(void)
{ 
 One_Wire_Bus=0;
 One_Wire_Delay(80);//总线拉低 488us 
 One_Wire_Bus=1;
 One_Wire_Delay(25);//总线拉高 158us;
}
/***********************************************************************/

/*******************读一个字节ds18b20 *********************************/
unsigned char One_Wire_Read_Byte(void)
{ 
 bit temp_bit;
 unsigned char i,result=0;
 for(i=0;i<8;i++)
 { 
  One_Wire_Bus=0;
  One_Wire_Bus=1; 
  temp_bit=One_Wire_Bus;
  One_Wire_Delay(9);//延时 62 us
  if(temp_bit)
   result|=0x01<<i;
 }
 return(result);  //返回ds18b20值
 
}

/*********向ds18b20写一个字节*********************/
void One_Wire_Write_Byte(unsigned char oww_dat)
{  
 unsigned char i;
 for(i=0;i<8;i++)
 { 
  One_Wire_Bus=0;
  if(oww_dat&0x01)One_Wire_Bus=1; 
  One_Wire_Delay(20);// 128 us
  One_Wire_Bus=1;
  oww_dat>>=1;
 }
 One_Wire_Delay(10);
}
/******************************************/
void Read_18B20(void)
{ 
 unsigned char tempH,tempL;
 Initize_One_Wire_Bus();
 One_Wire_Write_Byte(SkipRom);
 _nop_();
  //There is just one DS1820 on the bus;
 One_Wire_Write_Byte(ConvertTemperature);
 One_Wire_Delay(5);
  //Start to convert temperature;
 Initize_One_Wire_Bus();
 One_Wire_Write_Byte(SkipRom);
 _nop_();
 One_Wire_Write_Byte(ReadScratchpad);
 GetScratchpad[0]=One_Wire_Read_Byte();
  //Master samples the LSB temperature from the scratchpad;
 GetScratchpad[1]=One_Wire_Read_Byte();
  //Master samples the MSB temperature from the scratchpad;
 One_Wire_Delay(120);
 tempH=(GetScratchpad[1]<<4)|(GetScratchpad[0]>>4);  
 tempL=(GetScratchpad[0]&0x0f);
 Initize_One_Wire_Bus();
  //Issue a reset to terminate left parts;
 if(tempH&0x80)
 { 
  tempH=~tempH;
  tempL=~tempL+1;
  ResultSignal=1;
  //Negative temperature;
 }
 ResultTemperatureH=tempH;
 ResultTemperatureLL=decimalL[tempL];
 ResultTemperatureLH=decimalH[tempL];
  //Result of temperature; 
}//Read the byte0 and byte1 from scratchpad;
/***********************************************************************/

void main(void)
{ 
 
  TMOD=0x01;   //使用定时器0，选择方式1（16位定时器）
  TH0=(65536-3000)/256; //定时3MS初值
  TL0=(65536-3000)%256;
  ET0=1;    //开定时器0溢出中断
  EA=1;     //开总中断
  Initize_One_Wire_Bus();
 TR0=1;    //开定时器0
 while(TRUE )    
 {
 	if(timecount==10)    //每30ms采样一次温度可以修改采样时间
    {
     timecount=0;
     Read_18B20();
     dispbuff[4]=((ResultTemperatureH%100)/10);  //温度十位
	 dispbuff[3]=(ResultTemperatureH%10);     //温度个位
     dispbuff[2]=(ResultTemperatureLH/10);  //温度小数位
    } 
 }
  
}

/*********3MS中断服务程序*************/ 
void t0(void) interrupt 1
{ 
  TH0=(65536-3000)/256;
  TL0=(65536-3000)%256;
  timecount++;
	  if(disp_bit_count==3)
        P0=dot_numcode[dispbuff[disp_bit_count]];
      else
	    P0=numcode[dispbuff[disp_bit_count]];
 	  P1=bitcode[disp_bit_count];
	  disp_bit_count++;
	  if(disp_bit_count==8)
	     disp_bit_count=0; 
}