DS18B20学习

DS18B20

#include <reg52.h>
#include <intrins.h>
typedef unsigned char u8;
typedef unsigned int u16;

sbit IO_18b20 = P3^7;

void delay(u16 i)
{
while(i--);
}

bit Init_18b20()   //18b20初始化
{
   bit ack ;
   EA = 0;
   IO_18b20 = 0;
   delay(50);
   IO_18b20 = 1;
   delay(6);
   ack = IO_18b20;
    while(!IO_18b20);   //等待18b20释放总线
   EA = 1 ;

return ack ;
}

void write18b20(u8 dat)
{
   u8 i;
   EA = 0;
   for(i=0;i<8;i++)
   {
       IO_18b20 = 0;
       _nop_();
       _nop_();
       IO_18b20 = dat&0x01;
       delay(6);
       IO_18b20 = 1;
       dat >>= 1;
   }
   EA = 1;
}

u8 read18b20()
{
   u8 mask;
   u8 dat;
   EA = 0;
   for(mask = 0x01;mask != 0;mask<<=1)
   {
       IO_18b20 = 0;
       _nop_();
       _nop_();
       IO_18b20 = 1;
       _nop_();
       _nop_();
       if(!IO_18b20)
           dat &= ~mask;
       else
           dat |= mask;
       delay(6);
   }
   EA = 1;

return dat;
}

void Start18b20()
{
   bit ack;
    ack = Init_18b20();
   if(ack == 0)
   {
       write18b20(0xcc);   //跳过ROM操作命令
       write18b20(0x44);   //温度转换命令
   }
}

void DS18b20temp()
{
       bit ack;
    ack = Init_18b20();
   if(ack == 0)
   {
       write18b20(0xcc);
       write18b20(0xbe);      //发送读取温度命令
   }
}

int Get18b20temp()
{
   bit ack;
   int temp = 0;
   u8 LSB,MSB;
   ack = Init_18b20();
   if(ack == 0)
   {
       Start18b20();   //启动18b20，开始温度转化
b
       DS18b20temp();   //然后等待转换完后发送读取温度命令
       LSB = read18b20();   //读取温度值共16位，先读低字节
       MSB = read18b20();      //再读高字节
       temp = ((int)MSB<<8) + LSB;
   }
   return temp;

}

main

#include<reg52.h>
#define LED P0
typedef unsigned char u8;
typedef unsigned int u16;

bit Init_18b20();
void write18b20(u8 dat);
u8 read18b20();
void Start18b20();
void DS18b20temp();
int Get18b20temp();

sbit LSA = P2^2;
sbit LSB = P2^3;
sbit LSC = P2^4;

u8 code smgduan[] = {0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f};//显示0~9的值
u8 ledchar[8] = {0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00};
u8 flag1s = 0;
u8 i = 0;

void init()
{
   TMOD = 0x01;
   TH0 = 0xff;   //fff6 = 65526
   TL0 = 0xf6;
   TR0 = 1;
   ET0 = 1;
   EA = 1;
}

void Timer0() interrupt 1
{
   static u16 cnt;
   TH0 = 0xff;
   TL0 = 0xf6;
   cnt++;
   if(cnt == 1)      //定时10us
   {
       cnt = 0;
       flag1s = 1;
   }
   LED = 0x00;
   switch(i)
   {
       case(0):LSA = 0;LSB = 0;LSC = 0;i++;LED = ledchar[0];break;
       case(1):LSA = 1;LSB = 0;LSC = 0;i++;LED = ledchar[1];break;
       case(2):LSA = 0;LSB = 1;LSC = 0;i++;LED = ledchar[2];break;
       case(3):LSA = 1;LSB = 1;LSC = 0;i++;LED = ledchar[3];break;
       case(4):LSA = 0;LSB = 0;LSC = 1;i++;LED = ledchar[4];break;
       case(5):LSA = 1;LSB = 0;LSC = 1;i++;LED = ledchar[5];break;
       case(6):LSA = 0;LSB = 1;LSC = 1;i++;LED = ledchar[6];break;
       case(7):LSA = 1;LSB = 1;LSC = 1;i=0;LED = ledchar[7];break;
       default:break;
   }
}

void datapros(int temp)
{
   float tp;
   if(temp)
   {
       ledchar[0] = 0x00;
       tp=temp;    //因为数据处理有小数点所以将温度赋给一个浮点型变量
       //如果温度是正的那么，那么正数的原码就是补码它本身
       temp=tp*0.0625*100+0.5;
       if(flag1s == 1)
       {
           flag1s = 0;
           ledchar[1] = smgduan[temp/10000];
           ledchar[2] = smgduan[temp%10000/1000];
           ledchar[3] = smgduan[temp%1000/100] | 0x80;
           ledchar[4] = smgduan[temp%100/10];
           ledchar[5] = smgduan[temp%10];
       }
   }
}

void main()
{
   init();
   while(1)
   {
       datapros(Get18b20temp());   //数据处理函数
   }
}