基于51单片机的DS18B20温控系统程序

#include <reg52.h> #define uchar unsigned char #define uint unsigned int sbit DS=P3^7; //define interface uint temp; // variable of temperature /*uchar flag1; // sign of the result positive or negative*/ sbit A2=P2^2; sbit B2=P2^3; sbit C2=P2^4; unsigned char code table[]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d, 0x07,0x7f,0x6f,0x77,0x7c,0x39,0x5e,0x79,0x71}; unsigned char code table1[]={0xbf,0x86,0xdb,0xcf,0xe6,0xed,0xfd, 0x87,0xff,0xef}; void delay(uint xms) //delay { uint a,b; for(a=xms;a>0;a--) for(b=110;b>0;b--); } void dsreset(void) //send reset and initialization command 18B20复位，初始化函数 { uint i; DS=0; i=103; while(i>0)i--; DS=1; i=4; while(i>0)i--; } bit tmpreadbit(void) //read a bit 读1位数据函数 { uint i; bit dat; DS=0;i++; //i++ for delay DS=1;i++;i++; dat=DS; i=8;while(i>0)i--; return (dat); } uchar tmpread(void) //read a byte date 读1字节函数 { uchar i,j,dat; dat=0; for(i=1;i<=8;i++) { j=tmpreadbit(); dat=(j<<7)|(dat>>1); //读出的数据最低位在最前面，这样刚好一个字节在DAT里 } return(dat); } void tmpwritebyte(uchar dat) //write a byte to ds18b20 向1820写一个字节数据函数 { uint i; uchar j; bit testb; for(j=1;j<=8;j++) { testb=dat&0x01; dat=dat>>1; if(testb) //write 1 { DS=0; i++;i++; DS=1; i=8;while(i>0)i--; } else { DS=0; //write 0 i=8;while(i>0)i--; DS=1; i++;i++; } } } void tmpchange(void) //DS18B20 begin change 开始获取数据并转换 { dsreset(); delay(1); tmpwritebyte(0xcc); // address all drivers on bus 写跳过读ROM指令 tmpwritebyte(0x44); // initiates a single temperature conversion 写温度转换指令 } uint tmp() //get the temperature 读取寄存器中存储的温度数据 { float tt; uchar a,b; dsreset(); delay(1); tmpwritebyte(0xcc); tmpwritebyte(0xbe); a=tmpread(); //读低8位 b=tmpread(); //读高8位 temp=b; temp<<=8; //two byte compose a int variable 两个字节组合为1个字 temp=temp|a; tt=temp*0.0625; //温度在寄存器中是12位，分辨率是0.0625 temp=tt*10+0.5; //乘10表示小数点后只取1位，加0.5是四折五入 return temp; } void display(uint temp) //显示程序 { uchar bai,shi,ge,A1; bai=temp/100; A1=temp%100; shi=A1/10; ge=A1%10; A2=0;B2=0;C2=0; P0=table[bai]; //显示百位 delay(5); A2=1;B2=0;C2=0; P0=table1[shi]; //显示十位 delay(5); A2=0;B2=1;C2=0; P0=table[ge]; delay(5); //显示十位 } void main() { while(1) { tmpchange(); display(tmp()); } }