ds18b20.c

AVR单片机c语言的开发板程序

#include <avr/io.h>
#include "ds18b20.h"
#define BIT(X) (1 << X)
/************************************************************************* 
ds18b20头文件    
M16  内部8M         
*************************************************************************/ 
#define CLR_DIR_1WIRE DDRA&=~BIT(2)     //只要修改这里的参数就可以了！呵呵！ 
#define SET_DIR_1WIRE DDRA|=BIT(2)      //里面什么都不用该！ 
#define CLR_OP_1WIRE PORTA&=~BIT(2) 
#define SET_OP_1WIRE PORTA|=BIT(2)       
#define CHECK_IP_1WIRE (PINA & 0x04)    //检测 
unsigned char wmh,wml; 

//延时程序： 

//delay.h 
/*----------------------------------------------------------------------- 
延时函数 
系统时钟：8M 
-----------------------------------------------------------------------*/ 
static void delay_1us(void)                 //1us延时函数 
  { 
   asm("nop"); 
  } 

static void delay_nus(unsigned int n)       //N us延时函数 
  { 
   unsigned int i=0; 
   for (i=0;i<n;i++) 
   delay_1us(); 
  } 
   
static void delay_1ms(void)                 //1ms延时函数 
  { 
   unsigned int i; 
   for (i=0;i<1140;i++); 
  } 
   
static void delay_nms(unsigned int n)       //N ms延时函数 
  { 
   unsigned int i=0; 
   for (i=0;i<n;i++) 
   delay_1ms(); 
  } 

void init_1820()  
{  
    SET_DIR_1WIRE;                //设置PA2 为输出 
    SET_OP_1WIRE;   
    CLR_OP_1WIRE;  
    delay_nus(480);    //480us以上  
    SET_OP_1WIRE;  
    CLR_DIR_1WIRE;  
    delay_nus(20);     //15~60us  
    while(CHECK_IP_1WIRE);  
    SET_DIR_1WIRE;  
    SET_OP_1WIRE;  
    delay_nus(140);   //60~240us  
}  
void write_1820(unsigned char x)  
{     
     unsigned char m;  
    for(m=0;m<8;m++)  
    {  
       CLR_OP_1WIRE;  
       if(x&(1<<m))    //写数据了，先写低位的！ 
       SET_OP_1WIRE;  
       else  
       {CLR_OP_1WIRE;}  
       delay_nus(40);   //15~60us  
       SET_OP_1WIRE;  
    }  
     SET_OP_1WIRE;  
}  
unsigned char read_1820()  
{      
    unsigned char temp,k,n;  
    temp=0;  
    for(n=0;n<8;n++)  
       {  
      CLR_OP_1WIRE;  
      SET_OP_1WIRE;  
      CLR_DIR_1WIRE;  
      k=(CHECK_IP_1WIRE);    //读数据,从低位开始  
      if(k)  
      temp|=(1<<n);  
      else  
      temp&=~(1<<n);  
      delay_nus(50); //60~120us      
      SET_DIR_1WIRE;  
   }  
   return (temp);  
}   

unsigned char gettemp()                   //读取温度值 
{  
     unsigned char temh,teml,wm0,wm1,wm2,wm3;  
     init_1820();        //复位18b20  
     write_1820(0xcc);    
     write_1820(0x44);  // 发出转换命令
	 delay_nms(800); 
     init_1820();  
     write_1820(0xcc);    
     write_1820(0xbe);  //发出读命令
     teml=read_1820();  //读数据  
     temh=read_1820();  
     wm0=teml>>4; 
     wm1=temh<<4; 
     wm2=wm1+wm0;        //16进制转10进制 
     wm3=wm2/100; 
	return wm2;
}   

unsigned int get_temp(char num)
{
	unsigned char temh,teml,wm0,wm1,wm2,wm3;
	unsigned int temp = 0;
	if(num & 1)
	{
	     init_1820();  
	     write_1820(0xcc);  //发出读命令  
	     write_1820(0xbe);  
	     teml=read_1820();  //读数据  
	     temh=read_1820();  
	     wm0=teml>>4; 
	     wm1=temh<<4; 
	     wm2=wm1+wm0;
	     wm3=wm2/100; 
		 temp = (10 * ((unsigned int)teml & 0x0f) / 16) << 8;
		 temp |= (unsigned int)(wm2 & 0xff);
		return temp;
	}
	else
	{
	     init_1820();        //复位18b20  
	     write_1820(0xcc);   // 发出转换命令  
	     write_1820(0x44); 
		 return(0xffff);
	}
}