基于51DS18B20室内温度报警系统设计（留底）

#include<reg52.h>
#define uchar unsigned char
#define uint unsigned int
sbit DQ=P2^2;
sbit smg1=P2^4;
sbit smg2=P2^5;
sbit smg3=P2^6;
uchar temp;
unsigned char code smg_du[]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f,0x77,0x7c,0x39,0x5e,0x79,0x71,0x00};
unsigned char code smg_we[]={0x08,0x18,0x28,0x38,0x48,0x58,0x68,0x78};
void init_ds18b20(void);
void delay(uint t);
void write_byte(uchar dat);
uchar read_byte(void);
uchar readtemperature(void);
void display(void);
//************************************************
//延时函数，在12MHz的晶振频率下
//大约50us的延时
//************************************************
void delay_50us(uint t)
{
 uchar j;
 for(;t>0;t--)
        for(j=19;j>0;j--);
}
void main(void)
{
 while(1)
 {
  temp=readtemperature();
  display();
  
 }
 
 
  
}

void delay(uint t)
{
 while(t--); 
}
void init_ds18b20(void)
{
 uchar n;
 DQ=1;
 delay(8);
 DQ=0;
 delay(80);
 DQ=1;
 delay(8);
 n=DQ;
 delay(4);
}
void write_byte(uchar dat)
{
 uchar i;
 for(i=0;i<8;i++)
 {
  DQ=0;
  DQ=dat&0x01;
  delay(4);
  DQ=1;
  dat>>=1;
 }
 delay(4);
}
uchar read_byte(void)
{
 uchar i,value;
 for(i=0;i<8;i++)
 {
  DQ=0;
  value>>=1;
  DQ=1;
  if(DQ)
  value|=0x80;
  delay(4);
 }
 return value;
}
uchar readtemperature(void)
{
 uchar a,b;
 init_ds18b20();
 write_byte(0xcc); //跳过ROM
 write_byte(0x44); //启动温度测量
 delay(300);
 init_ds18b20();
 write_byte(0xcc);
 write_byte(0xbe);
 a=read_byte();
 b=read_byte();
 b<<=4;
 b+=(a&0xf0)>>4;
 return b;
}

void display(void)
{
 smg3=0;
 smg2=0;
 smg1=0;
 P1=smg_du[temp%10];
 delay_50us(20);
 smg2=0;
 smg1=1;
 P1=smg_du[temp/10];
 delay_50us(20);
   
}

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