蓝桥杯单片机必备知识—–(7)温度传感器整数和浮点数

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发布于 2021-04-14 02:10:21

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蓝桥杯单片机必备知识—–(7)温度传感器整数和浮点数

注：一般蓝桥杯省赛会出温度传感器整数显示；而蓝桥杯国赛则会出温度传感器浮点数显示

onewire.h添加

unsigned char rd_temperature(void);

onewire.c 整数显示

官方给的数据包中延时函数有问题需修改 整数

//延时函数修改
//单总线延时函数
void Delay_OneWire(unsigned int t)  //STC89C52RC
{
   
	char  i;
	while(t--)
		for(i = 0;i<12;i++);
}
//添加读取温度函数
unsigned char rd_temperature(void)
{
   
	unsigned char low,high;
	char temp;
	
	init_ds18b20();
	Write_DS18B20(0xcc);
	Write_DS18B20(0x44);
	Delay_OneWire(200);
	
	init_ds18b20();
	Write_DS18B20(0xcc);
	Write_DS18B20(0xbe);
	
	low = Read_DS18B20();
	high = Read_DS18B20();
	temp = high <<4;
	temp |=(low >> 4);
	
	return temp;
}

测试结果

onewire.h添加

float rd_temperature(void);

onewire.c 浮点数显示

//延时函数修改
//单总线延时函数
void Delay_OneWire(unsigned int t)  //STC89C52RC
{
   
	char  i;
	while(t--)
		for(i = 0;i<12;i++);
}
//添加读取温度函数
float rd_temperature(void)
{
   
    unsigned int temp;
	float temperature;
    unsigned char low,high;
  
  	init_ds18b20();
  	Write_DS18B20(0xCC);
  	Write_DS18B20(0x44); //启动温度转换
  	Delay_OneWire(200);

  	init_ds18b20();
  	Write_DS18B20(0xCC);
  	Write_DS18B20(0xBE); //读取寄存器

  	low = Read_DS18B20(); //低字节
  	high = Read_DS18B20(); //高字节
/** 精度为0.0625摄氏度 */  
	temp = (high&0x0f);
	temp <<= 8;
	temp |= low;
	temperature = temp*0.0625;
  
  	return temperature;
}

测试结果：

全部代码粘贴

ONEWIRE.H

#ifndef __ONEWIRE_H
#define __ONEWIRE_H

unsigned char rd_temperature(void);  //; ;

#endif

ONEWIRE.C

#include "reg52.h"

sbit DQ = P1^4;  //单总线接口

//单总线延时函数
void Delay_OneWire(unsigned int t)  //STC89C52RC
{
   
	char  i;
	while(t--)
		for(i = 0;i<12;i++);
}

//通过单总线向DS18B20写一个字节
void Write_DS18B20(unsigned char dat)
{
   
	unsigned char i;
	for(i=0;i<8;i++)
	{
   
		DQ = 0;
		DQ = dat&0x01;
		Delay_OneWire(5);
		DQ = 1;
		dat >>= 1;
	}
	Delay_OneWire(5);
}

//从DS18B20读取一个字节
unsigned char Read_DS18B20(void)
{
   
	unsigned char i;
	unsigned char dat;
  
	for(i=0;i<8;i++)
	{
   
		DQ = 0;
		dat >>= 1;
		DQ = 1;
		if(DQ)
		{
   
			dat |= 0x80;
		}	    
		Delay_OneWire(5);
	}
	return dat;
}

//DS18B20设备初始化
bit init_ds18b20(void)
{
   
  	bit initflag = 0;
  	
  	DQ = 1;
  	Delay_OneWire(12);
  	DQ = 0;
  	Delay_OneWire(80);
  	DQ = 1;
  	Delay_OneWire(10); 
    initflag = DQ;     
  	Delay_OneWire(5);
  
  	return initflag;
}

unsigned char rd_temperature(void)
{
   
	unsigned char low,high;
	char temp;
	
	init_ds18b20();
	Write_DS18B20(0xcc);
	Write_DS18B20(0x44);
	Delay_OneWire(200);
	
	init_ds18b20();
	Write_DS18B20(0xcc);
	Write_DS18B20(0xbe);
	
	low = Read_DS18B20();
	high = Read_DS18B20();
	temp = high <<4;
	temp |=(low >> 4);
	
	return temp;
}

MAIN.C

#include <stc15f2k60s2.h>
#include "onewire.h"
#define uchar unsigned char
#define uint unsigned int


code unsigned char tab[] = {
   0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90,0xff};
uchar dspbuf[8] = {
   10,10,10,10,10,10,10,10};
uchar intr = 0,temperature;
uchar temper_flag = 1;


void load();
void display();
void cls()
{
   
	P2 = (P2 & 0xa0);
	P0 = 0x00;
	P2 = 0x1f;
	
	P2 = (P2 & 0x80);
	P0 = 0xff;
	P2 = 0x1f;
}

void main()
{
   
	cls();
	AUXR = 0x80;
	TMOD = 0x00;
	TL0 = 0xcd;
	TH0 = 0xd4;
	TF0 = 0;
	TR0 = 1;
	ET0 = 1;
	EA = 1;
	while(1)
	{
   
		if(temper_flag)
		{
   
			temper_flag = 0;
			temperature = rd_temperature();
		}
	}
}

void time0(void) interrupt 1
{
   
	if(++intr == 50){
   
		temper_flag = 1;
		intr = 0;
	}
	display();
}

void load()
{
   
	dspbuf[7] = temperature % 10;
	dspbuf[6] = temperature / 10;
}

void display()
{
   
	static unsigned char dspcom = 0;
	load();
	P2 = (P2 & 0x1f) | 0xe0;
	P0 = 0xff;
	P2 = 0x1f;
	
	P2 = (P2 & 0x1f) | 0xc0;
	P0 = 1<<dspcom;
	P2 = 0x1f;
	
	P2 = (P2 & 0x1f) | 0xe0;
	P0 = tab[dspbuf[dspcom]];
	P2 = 0x1f;
	
	if(++dspcom == 8)dspcom = 0;
}