DS18B20读取温度（带小数）

由于DS18B20对时间精度要求很高，所以在写读取温度之前一定要改时序

1. 单总线延时函数

//单总线延时函数
void Delay_OneWire(unsigned int t)
{
	t*=12;          //t改成t*12
    while(t--);
}

2. 读取温度（整数）

unsigned char read_temperature1()
{
		unsigned char temp1;
		unsigned char low,high;
	
		Init_DS18B20();
		Write_DS18B20(0xcc);
		Write_DS18B20(0x44);
		Delay_OneWire(200);
	
		Init_DS18B20();
		Write_DS18B20(0xcc);
		Write_DS18B20(0xbe);
		Delay_OneWire(200);
	
		low = Read_DS18B20();            //先读低，再读高
		high = Read_DS18B20();
		
		temp1=high<<4;       
		temp1|=(low&0xf0)>>4;
	
		return temp1;	
}

3. 读取温度（带小数）

float read_temperature2()
{
		float temp2;                    //**注意带小数，使用float型**
		unsigned int temp;          //16位
		unsigned char low,high;
	
		Init_DS18B20();
		Write_DS18B20(0xcc);
		Write_DS18B20(0x44);
		Delay_OneWire(200);
	
		Init_DS18B20();
		Write_DS18B20(0xcc);
		Write_DS18B20(0xbe);
		Delay_OneWire(200);
	
		low = Read_DS18B20();
		high = Read_DS18B20();
		
		temp = high&0x0f;
		temp = temp<<8|low;
		temp2 = temp*0.0625;   //最小精度0.0625
		return temp2;	
}

4. 主函数里的变换

uchar temp1;
uint temp2;
float temp_value;
bit temp_flag;
void main()
{
		CloseFucker();
		Timer0Init();
		while(1)
		{
				if(temp_flag)
				{
						temp1 = read_temperature1();              //读取整数温度值
						temp_value = 10*read_temperature2();  //float型读取带小数温度值，乘10把小数提取
						temp2 = (uint)temp_value;            //化为整型可以取余
						temp_flag=0;
				}				
				ShowTemp();
		}
}

代码

main.c

******************************************************************************
* 文件名：读取温度（带整数和小数）
* 描  述：
* 作  者：思索与猫
* 日  期:  19/3/8 
* 备  注：左边：整数      右边：带小数
*         
******************************************************************************
#include<stc15f2k60s2.h>
#include<onewire.h>
#define uchar unsigned char
#define uint unsigned int
	
uchar code duan[] = {0x3F,0x06,0x5B,0x4F,0x66,0x6D,0x7D,0x07,0x7F,0x6F,0x00,0x40,0x039,
					 0xBF,0x86,0xDB,0xCF,0xE6,0xED,0xFD,0x87,0xFF,0xEF};  //带小数0~9
uchar dispbuff[8];
uchar temp1;     //注意数据类型
uint temp2;
float temp_value;
bit temp_flag;
//function
void CloseFucker();
void Timer0Init();
void Display();
void ShowTemp();

void main()
{
		CloseFucker();
		Timer0Init();
		while(1)
		{
				if(temp_flag)
				{
						temp1 = read_temperature1();
						temp_value = 10*read_temperature2();
						temp2 = (uint)temp_value;
						temp_flag=0;
				}				
				ShowTemp();
		}
}
void ShowTemp()
{
		dispbuff[0] = temp1/10;
		dispbuff[1] = temp1%10;
		dispbuff[2] = 12;
		dispbuff[3] = 10;
		dispbuff[4] = temp2/100;
		dispbuff[5] = temp2/10%10+13;
		dispbuff[6] = temp2%10;
		dispbuff[7] = 12;
}
void Display()
{
		static uchar index = 0;
		P2 = (P2&0x1f)|0xe0;
		P0 = 0xff;
		P2 = P2&0x1f;
	
		P2 = (P2&0x1f)|0xc0;
		P0 = 1<<index;
		P2 = P2&0x1f;
	
		P2 = (P2&0x1f)|0xe0;
		P0 = ~duan[dispbuff[index]];
		P2 = P2&0x1f;
	
		index++;
		index &= 0x07;	
}
void T0_time() interrupt 1
{
		static uint temp_count = 0;
		TL0 = 0x40;		
		TH0 = 0xA2;	
		Display();
		if(++temp_count == 500)
		{
				temp_count=0;
				temp_flag=1;
		}			
}
void Timer0Init()		//12Mhz 2ms
{
		AUXR |= 0x80;		
		TMOD &= 0xF0;		
		TL0 = 0x40;		
		TH0 = 0xA2;		
		TF0 = 0;		
		TR0 = 1;	
		ET0=1;
		EA=1;
}
void CloseFucker()
{
		P2 = (P2&0x1f)|0xa0;
		P0 = 0xa0;
		P2 = P2&0x1f;
}

onewire.h

#ifndef _ONEWIRE_H
#define _ONEWIRE_H

#include "stc15f2k60s2.h"

#define OW_SKIP_ROM 0xcc
#define DS18B20_CONVERT 0x44
#define DS18B20_READ 0xbe

//pin
sbit DQ = P1^4;

//function
void Delay_OneWire(unsigned int t);
void Write_DS18B20(unsigned char dat);
bit Init_DS18B20(void);
unsigned char Read_DS18B20(void);

unsigned char read_temperature1();
float read_temperature2();
#endif

onewire.c

#include "onewire.h"

void Delay_OneWire(unsigned int t)
{
	t*=12;
  while(t--);
}

bit Init_DS18B20(void)
{
	bit initflag = 0;
	DQ = 1;
	Delay_OneWire(12);
	DQ = 0;
	Delay_OneWire(80); 
	DQ = 1;
	Delay_OneWire(10); 
	initflag = DQ;    
	Delay_OneWire(5);
  
	return initflag;
}

void Write_DS18B20(unsigned char dat)
{
	unsigned char i;
	for(i=0;i<8;i++)
	{
		DQ = 0;
		DQ = dat&0x01;
		Delay_OneWire(5);
		DQ = 1;
		dat >>= 1;
	}
	Delay_OneWire(5);
}

unsigned char Read_DS18B20(void)
{
	unsigned char i;
	unsigned char dat;
  
	for(i=0;i<8;i++)
	{
		DQ = 0;
		dat >>= 1;
		DQ = 1;
		if(DQ)
		{
			dat |= 0x80;
		}	    
		Delay_OneWire(5);
	}
	return dat;
}

unsigned char read_temperature1()  //读取温度（整数）
{
		unsigned char temp1;
		unsigned char low,high;
	
		Init_DS18B20();
		Write_DS18B20(0xcc);
		Write_DS18B20(0x44);
		Delay_OneWire(200);
	
		Init_DS18B20();
		Write_DS18B20(0xcc);
		Write_DS18B20(0xbe);
		Delay_OneWire(200);
	
		low = Read_DS18B20();
		high = Read_DS18B20();
		
		temp1=high<<4;
		temp1|=(low&0xf0)>>4;
	
		return temp1;	
}

float read_temperature2()   //读取温度（小数）
{
		float temp2;
		unsigned int temp;
		unsigned char low,high;
	
		Init_DS18B20();
		Write_DS18B20(0xcc);
		Write_DS18B20(0x44);
		Delay_OneWire(200);
	
		Init_DS18B20();
		Write_DS18B20(0xcc);
		Write_DS18B20(0xbe);
		Delay_OneWire(200);
	
		low = Read_DS18B20();
		high = Read_DS18B20();
		
		temp = high&0x0f;
		temp = temp<<8|low;
		temp2 = temp*0.0625;
		return temp2;	
}