（13） Simple temperature alarm device based on 51 single chip microcomputer

Catalog

Demand analysis

Function realization

Code implementation  

Running results  

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         A temperature measuring device was just made in the afternoon , We continue to work in the evening . Now that you can measure the temperature , Let's combine the previous knowledge points , To make a temperature alarm device ！

Demand analysis

         Temperature alarm device plays an extremely important role in many places , Such as the storage of laboratory instruments or drugs , Remind the occurrence of fire and so on , For example, the relative humidity is often greater than 95%、 No fireworks 、 There is a lot of dust 、 Under normal circumstances, there is smoke and dust retention 、 The kitchen 、 Boiler Room 、 Generator room 、 Drying workshop 、 Smoking Room 、 Other halls and public places that are not suitable for installing smoke detectors . meanwhile , We hope that the temperature range can be regulated , It's better to have memory function , This can prevent the need to readjust the safe temperature range after power failure .

Function realization

         Get the temperature we use DS18B20 To achieve , For details, please see the article introduced before (1 Bar message ) （ Twelve ）51 Single chip microcomputer ---- use DS18B20 Shallow measurement （ jiang ） The outdoor temperature in the West _Meursault639 The blog of -CSDN Blog ;

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         To display the temperature, we use LCD1602 To achieve ;

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         We can adjust the safe temperature range by pressing the key , But you have to use a timer to scan , Otherwise, the acquisition temperature will be affected ;

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         The alarm function is realized by buzzer ;

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         Memory function we use AT24C02 To achieve , You can also refer to the previous writing , Timer scanning is also included (1 Bar message ) （ 11、 ... and ）51 Single chip microcomputer —— use AT24C02 Realize the storage of stopwatch data （ Attached with achievement display ）_Meursault639 The blog of -CSDN Blog ;

Code implementation  

#include <REGX52.H>
#include "LCD1602.h"
#include "DS18B20.h"
#include "Delay.h"
#include "AT24C02.h"
#include "Key.h"
#include "Time0.h"
#include "Buzzer.h"

float T,TShow;//  temperature , Show the temperature 
char TL,TH;
unsigned char KeyNum;

void main()
{		
	DS18B20_ConvertT();// Switch the primary temperature before power on , Prevent errors in reading data for the first time 
	Delay(1000);	// Wait for the conversion to complete 
	TH=AT24C02_ReadByte(0);	// Read temperature threshold data 
	TL=AT24C02_ReadByte(1);
	if(TH>125 || TL<-55 || TH<=TL)
	{
		TH=20;			// If the threshold is illegal , Set to the default value 
		TL=15;
	}
	LCD_Init();
	LCD_ShowString(1,1,"T:");
	LCD_ShowString(2,1,"TH:");
	LCD_ShowString(2,9,"TL:");
	LCD_ShowSignedNum(2,4,TH,3);
	LCD_ShowSignedNum(2,12,TL,3);
	Timer0_Init();
	
	while(1)
	{
		KeyNum=Key();
		//  Temperature reading and display 
		DS18B20_ConvertT();// Conversion temperature 
		T = DS18B20_ReadT();// Reading temperature 
		if(T < 0){
			LCD_ShowChar(1,3,'-');// Show minus sign 
			TShow = -T;// Change the temperature to a positive number 
		}else{
			LCD_ShowChar(1,3,'+');// Show positive sign 
			TShow = T;
		}
		LCD_ShowNum(1,4,TShow,3);// Display temperature integer part 
		LCD_ShowChar(1,7,'.');
		LCD_ShowNum(1,8,(unsigned long)(TShow*100)%100,2);// Display decimal part of temperature , Keep two decimal places 
		
		//  Threshold judgment and display 
		if(KeyNum)
		{
			if(KeyNum==1)	//K1 Key ,TH Self increasing 
			{
				TH++;
				if(TH>125){TH=125;}
			}
			if(KeyNum==2)	//K2 Key ,TH Self reduction 
			{
				TH--;
				if(TH<=TL){TH++;}
			}
			if(KeyNum==3)	//K3 Key ,TL Self increasing 
			{
				TL++;
				if(TL>=TH){TL--;}
			}
			if(KeyNum==4)	//K4 Key ,TL Self reduction 
			{
				TL--;
				if(TL<-55){TL=-55;}
			}
			LCD_ShowSignedNum(2,4,TH,3);	// Display threshold data 
			LCD_ShowSignedNum(2,12,TL,3);	
			AT24C02_WriteByte(0,TH);		// Write to At24C02 Kept in 
			Delay(5);
			AT24C02_WriteByte(1,TL);
			Delay(5);
	}
		if(T>TH)			// Cross border judgment 
		{
			LCD_ShowString(1,13,"OV:H");
			Buzzer_Time(100);
		}
		else if(T<TL)
		{
			LCD_ShowString(1,13,"OV:L");
			Buzzer_Time(100);
		}
		else
		{
			LCD_ShowString(1,13,"    ");
		}
}
	}

	void Timer0_Routine() interrupt 1
{
	static unsigned int T0Count;
	TL0 = 0x66;		// Set the initial timing value 
	TH0 = 0xFC;;	
	T0Count++;
	if(T0Count>=20)
	{
		T0Count=0;
		Key_Loop();	// Every time 20ms Call the key driver function once 
	}
}

         Each module has been introduced in the previous article , If there are interested students , It's OK to find me to play with the complete code , I will continue to improve this , I also hope the boss can give some advice .

Running results  

Temperature alarm