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标题: DS18B20读写显示程序 [打印本页]

作者: winnie 时间: 2009-4-26 11:38
标题: DS18B20读写显示程序
/*DS18B20,4MHZ晶振读写显示程序PIC16F873A*/
#include<pic.h>
#include<sys.h>
#include <math.h>
#define  QD  RC7
#define uchar unsigned char
unsigned char s[4];
const unsigned char table[20]={0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xd8,
                           0x80,0x90,0x88,0x83,0xc6,0xa1,0x86,0x8e,
                           0x7f,0xbf,0x89,0xff};
void delay(uchar a)
{
while(a--);
}
void H_BCD (unsigned int j)
{

s[0]=j%10;
s[1]=(j/10)%10;
s[2]=(j/100)%10;
s[3]=j/1000;
}
void SPIINIT()
{
PIR1=0;
SSPCON=0x30;
SSPSTAT=0xC0;
TRISC=0x00;
}
void initial()
{
TRISC=0x00;
INTCON=0x00;
RC3=0;
}
void SPILED( data)
{
SSPBUF=data;
do
{
;
}while(SSPIF==0);
SSPIF=0;
}

uchar  Readchar()
  {
   uchar i=0;
   uchar dat=0;
   TRISC7=0;
   for(i=8;i>0;i--)
   {
      TRISC7=0;
      QD=0;
      dat=dat>>1;
      QD=1;
   TRISC7=1;
   if(QD)
   dat=dat|0x80;
   delay(8);
   }
return(dat);
  }

RESTDS18B20()
{
   uchar x=0;
   TRISC7=0;
   QD=1;
   delay(1);
   QD=0;
   delay(130);
   QD=1;
   delay(20);
   TRISC7=1;
   x=QD;
   delay(35);
}
void Writechar(uchar dat)
{

   uchar h;
   TRISC7=0;
   for (h=0;h<8;h++)
   {
      QD=0;
      QD=dat&0x01;
      delay(8);
      QD=1;
      dat>>=1;
      }
      delay(6);
   }
unsigned int Readtem()
{
   uchar a=0;
   uchar b=0;
   unsigned int t=0;
   RESTDS18B20();
   Writechar(0xcc);
   Writechar(0x44);
   RESTDS18B20();
   Writechar(0xcc);
   Writechar(0xbe);
   a=Readchar();
   b=Readchar();
   t=b;
   t<<=8;
   t=t|a;
   return(t);
   }

main()
{

unsigned int i=0;
unsigned char j,data;
SPIINIT();
   while(1)
   {
      i=Readtem();
      i=(unsigned int)(i*0.0625);
      H_BCD (i);

      for(j=0;j<4;j++)
         {
         data=table[s[j]];
         SPILED(data);
         }

   RC4=1;
   RC4=0;
   }
   }

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