STC89C52 single chip microcomputer simple calculator design and code demonstration

Catalog

First, select hardware and software according to the functions to be realized ：

hardware component

Software part

Input part ：

Calculation part ：

Continuous calculation ：

Source code example ：

The main function ：

Keyboard entry ：

LCD1602 Show ：

Buzzer ：

The time delay function ：

---

First, select hardware and software according to the functions to be realized ：

First of all, the functions we want to realize are ： Multi bit display , Decimal calculation , Continuous calculation , The symbol is modified by mistake ,,

hardware component

be used LCD1602 display , Matrix keyboard , Buzzer （ Yes or no ）

The reason why there is no digital tube here is , The nixie tube needs to be scanned , And for addition, subtraction, multiplication and division, these symbols are not well displayed , Instead, it uses relatively simple LCD1602 To display

The matrix keyboard module is relatively simple ： Schematic diagram is as follows ：

Software part

Input part ：

Obviously, it is necessary to input two or more numbers to be calculated . Input operation ： Every time you enter a number , The previous numbers must be shifted forward . And for the fractional part , That is, every digit you enter , The numbers are displayed one after the other .（ Some students may not be used to looking at the front when inputting numbers 0000,, You can count overflow variables , If there are several digits, it will show how many digits are used if sentence ）

Count overflow variables ： It is to count the number of digits of the input number so as to ensure that the total length of the input number will not exceed the screen , When the maximum length is reached, the display function is limited to achieve the effect

Calculation part ：

Secondly, we should design the subroutines of addition, subtraction, multiplication and division , But our first design , Therefore, the number of digits calculated is relatively small , So the result of the interaction between variables is stored in the third variable , Then, just display it .

The input number may be an integer or a decimal , Taking multiplication as an example, the possible cases of calculation are ：

Integers x Integers

decimal x Integers

Integers x decimal

decimal x decimal

For the sake of representation , What I designed here is to divide a decimal into integer part and decimal part to store ; That is to say, for example, a 2 Decimal place ：number= Integral part +（ The fractional part *0.01） If we just want to calculate integers , that （ The fractional part *0.01） by 0 It will not affect the following calculation

After entering the integer part of a number , After pressing the operation symbol, the next step is to input the second number . But if you press the decimal point , Then the input of operation symbols will be delayed , The next step is to input the number after the decimal point , Then press the operation symbol , Is the input of the second number . In the process of pressing each key , We can also combine the buzzer , Every click rings . Make sure we actually press this button

Continuous calculation ：

There is also the calculation of multiple numbers , Our daily use of calculators may be more than just right 2 Between numbers , There may be an addition between these numbers , reduce , ride , Division and many other operations .

In general, I do this by 2 Based on the calculation between two numbers , The first input of 2 The calculated result of a number is stored in the first number , The second digit is cleared （ Count overflow variables should also be cleared , Otherwise, after the count overflow variable reaches the specified value, the second number cannot be entered ）.

Here is the following ：

Also mark the symbols to be calculated , If this flag is detected in the function that inputs the first number, it will jump out and directly enter the second number （ Since we have stored the result of the previous operation into the variable of the first number, we can only input the second number ）

What do you say , The train of thought is relatively clear

Source code example ：

The main function ：

#include <REGX52.H>
#include "LCD1602.h"
#include "delay.h"
#include "jianpan.h"
#include "Buzzer.h"

/*
number1 Key entered for the first time 
number2 Key entered for the second time 
number3 Key entered for the third time 
number4 Key entered for the fourth time 
number For the calculation result 

password1 and password3 constitute number1,password2 and password4 constitute number2
count1,count2,count3,count4 Count variables to avoid overflow of input numbers 


 The calculated figure may be ：
 Integers and integers 
 Integers and decimals 
 Decimals and integers 
 Decimals and decimals 

 Key description ：
 On the keyboard S1 To S9 Namely 1 To 9, then S10 yes 0
S11 It's the decimal point ,S12 It is the clear key when the first number is input , After the second number is entered, it is the equal key 
S13 To S16 They are plus , reduce , ride , except .
*/

float number,password1,password2;
unsigned long	number1,number2,number3,number4,password3,password4;
unsigned char symbol,count1,count2,count3,count4;
void main(){
while(1){  
	 LCD_Init();
	 LCD_ShowString(1,1,"Calculator x4.0");
   LCD_ShowString(2,1,"Wellcome");
	 password3=0;
   count2=0;
	while(1){
      if(symbol==13||symbol==14||symbol==15||symbol==16)
      {break;}
	 
		  number1=jianpan();		
		  if(number1){		
	  	Buzzer_Time(100);

			if(number1==12){
			LCD_ShowString(2,1,"            ");
		  count1=0;
			password1=0;
			LCD_ShowNum(2,1,password1,8); 
			}			

			if(number1<=10){

				if(count1<8){// Input at most 8 position , Avoid spillovers 

					  password1=10*password1;// Here two lines are the key , Shift the input single digits in sequence 
					  password1=number1%10+password1;			      

					  if(count1>=0)
							LCD_ShowNum(2,8,password1,1);
						  LCD_ShowString(2,1,"       ");
						if(count1>=1)
							LCD_ShowNum(2,7,(unsigned long)(password1/10)%10,1);
						  LCD_ShowString(2,1,"      ");
						if(count1>=2)
							LCD_ShowNum(2,6,(unsigned long)(password1/100)%10,1);
						  LCD_ShowString(2,1,"     ");
						if(count1>=3)
							LCD_ShowNum(2,5,(unsigned long)(password1/1000)%10,1);
						  LCD_ShowString(2,1,"    ");
						if(count1>=4)
							LCD_ShowNum(2,4,(unsigned long)(password1/10000)%10,1);
						  LCD_ShowString(2,1,"   ");
						if(count1>=5)
							LCD_ShowNum(2,3,(unsigned long)(password1/100000)%10,1);
						  LCD_ShowString(2,1,"  ");
						if(count1>=6)
							LCD_ShowNum(2,2,(unsigned long)(password1/1000000)%10,1);
						  LCD_ShowString(2,1," ");
						if(count1>=7)
							LCD_ShowNum(2,1,(unsigned long)(password1/10000000)%10,1);

				}
				   count1++;					 				 			 				 			  				  
		}

	  	if(number1==11)// no need switch,case Can improve fault tolerance , Changing the choice of symbols many times 
			break;		  
			if(number1==13){	 
			LCD_ShowString(2,1,"            ");	 
			LCD_ShowChar(2,1,'+');   
			symbol=number1;			
			break;
			}
			if(number1==14){	  		
			LCD_ShowString(2,1,"            ");
			LCD_ShowChar(2,1,'-');
			symbol=number1;				
			break;
			}
			if(number1==15){
			LCD_ShowString(2,1,"            ");
			LCD_ShowChar(2,1,'*');
			symbol=number1;				
			break;
			}	
			if(number1==16){
			LCD_ShowString(2,1,"            ");
			LCD_ShowChar(2,1,'/');
			symbol=number1;				
			break;
			} 			

		}
}		
    	while(1){
	 
	    if(symbol==13){ 
			LCD_ShowString(2,1,"        ");
			LCD_ShowChar(2,1,'+');				 
			break;
			}
			if(symbol==14){ 
			LCD_ShowString(2,1,"        ");
			LCD_ShowChar(2,1,'-');				 
			break;
			}
			if(symbol==15){ 
			LCD_ShowString(2,1,"        ");
			LCD_ShowChar(2,1,'*');				 
			break;
			}
			if(symbol==16){ 
			LCD_ShowString(2,1,"        ");
			LCD_ShowChar(2,1,'/');				 
			break;
			}
	 
			number2=jianpan();	
	    if(number1==11){// If you last entered a decimal point , Then enter this cycle , Otherwise you won't get into ( When the first number is an integer )			
			   LCD_ShowChar(2,9,'.');				
	  		 if(number2){
	  		 Buzzer_Time(100);
				 if(number2<=10){
							 if(count2<3){// Input at most 3 position , Avoid spillovers 					
										password3=10*password3;// Here two lines are the key , Shift the input single digits in sequence 
										password3=number2%10+password3;										

								    if(count2>=0)
										{
										  LCD_ShowNum(2,10,password3,1); 
										}
										if(count2>=1)
										{ 
											LCD_ShowNum(2,10,(password3/10)%10,1);	
										  LCD_ShowNum(2,11,password3,1);
                      										
										}
										if(count2>=2)
										{
										  LCD_ShowNum(2,12,password3,1); 
											LCD_ShowNum(2,11,(password3/10)%10,1); 
											LCD_ShowNum(2,10,(password3/100)%10,1);
										}
																
//								    LCD_ShowNum(2,10,password3,1); 
//										LCD_ShowNum(2,11,(password3/10)%10,1); 
//										LCD_ShowNum(2,12,(password3/100)%10,1);					
                    
							 }
							    	count2++;					 				 			 				 			  				  
						}

				if(number2==13){// Symbol display 
				LCD_ShowString(2,1,"            ");	 
				LCD_ShowChar(2,1,'+');
				symbol=number2;		
				break;
				}
				if(number2==14){	  		
				LCD_ShowString(2,1,"            ");
				LCD_ShowChar(2,1,'-');
        symbol=number2;						
				break;
				}
				if(number2==15){
				LCD_ShowString(2,1,"            ");
				LCD_ShowChar(2,1,'*');
        symbol=number2;						
				break;
				}	
				if(number2==16){
				LCD_ShowString(2,1,"            ");
				LCD_ShowChar(2,1,'/');
				symbol=number2;						
				break;
		    }
						
			}		
	 }
     else
		 break;
}
			
password2=0;//( One thing to note here is that when performing continuous operations , The second input number should be cleared , Otherwise, the third input will be based on the second input )
password4=0;	
count3=0;//( One thing to note here is that when performing continuous operations , Count variables should be cleared , Otherwise, you may not be able to input numbers later **)
count4=0;

  while(1){
	    number3=jianpan();		
		  if(number3){
			Buzzer_Time(100);
			if(number3<=10){
		  if(count3<8){// Input at most 8 position , Avoid spillovers 
				
						password2=10*password2;// Here two lines are the key , Shift the input single digits in sequence 
						password2=number3%10+password2;	      

     				if(count3>=0)
							LCD_ShowNum(2,8,password2,1);
						  LCD_ShowString(2,1,"       ");
						if(count3>=1)
							LCD_ShowNum(2,7,(unsigned long)(password2/10)%10,1);
						  LCD_ShowString(2,1,"      ");
						if(count3>=2)
							LCD_ShowNum(2,6,(unsigned long)(password2/100)%10,1);
						  LCD_ShowString(2,1,"     ");
						if(count3>=3)
							LCD_ShowNum(2,5,(unsigned long)(password2/1000)%10,1);
						  LCD_ShowString(2,1,"    ");
						if(count3>=4)
							LCD_ShowNum(2,4,(unsigned long)(password2/10000)%10,1);
						  LCD_ShowString(2,1,"   ");
						if(count3>=5)
							LCD_ShowNum(2,3,(unsigned long)(password2/100000)%10,1);
						  LCD_ShowString(2,1,"  ");
						if(count3>=6)
							LCD_ShowNum(2,2,(unsigned long)(password2/1000000)%10,1);
						  LCD_ShowString(2,1," ");
						if(count3>=7)
							LCD_ShowNum(2,1,(unsigned long)(password2/10000000)%10,1);
	
				 }
				 count3++;
	   }		 				 		 		 
 
     if(number3==11){break;}
		 if(number3==12){
			 
			  if(count2==1) password3=password3*100;// Using overflow variables , Implement a , Data with two decimal places and data with three decimal places are unified 
				if(count2==2) password3=password3*10;
			 
	   switch (symbol){// Integers ( decimal )x decimal 
							case 13:  number=(password1+password3*0.001)+(password2+password4*0.001);  break; 	
							case 14:  number=(password1+password3*0.001)-(password2+password4*0.001);  break;
							case 15:  number=(password1+password3*0.001)*(password2+password4*0.001);  break;
							case 16:  number=(password1+password3*0.001)/(password2+password4*0.001);  break;
						}
      
		 	  LCD_ShowString(2,1,"result:");
				LCD_ShowNum(2,8,number,1); 
				LCD_ShowNum(2,7,(unsigned long)(number/10)%10,1); 
				LCD_ShowNum(2,6,(unsigned long)(number/100)%10,1); 
				LCD_ShowNum(2,5,(unsigned long)(number/1000)%10,1); 
				LCD_ShowNum(2,4,(unsigned long)(number/10000)%10,1); 
				LCD_ShowNum(2,3,(unsigned long)(number/100000)%10,1); 
				LCD_ShowNum(2,2,(unsigned long)(number/1000000)%10,1); 
				LCD_ShowNum(2,1,(unsigned long)(number/10000000)%10,1);
		  
        LCD_ShowChar(2,9,'.');		
        LCD_ShowNum(2,10,(unsigned long)(number*1000)%1000,3);


		 }

				if(number3==13||number3==14||number3==15||number3==16)
					{ 
						if(count2==1) password3=password3*100;// Using overflow variables in continuous operations , Implement a , Data with two decimal places and data with three decimal places are unified 		
						if(count2==2) password3=password3*10;
						
					switch (symbol){// Integers ( decimal )x decimal 
					case 13:  number=(password1+password3*0.001)+(password2+password4*0.001);  break; 	
					case 14:  number=(password1+password3*0.001)-(password2+password4*0.001);  break;
					case 15:  number=(password1+password3*0.001)*(password2+password4*0.001);  break;
					case 16:  number=(password1+password3*0.001)/(password2+password4*0.001);  break;
					}
					password1=number;
					symbol=number3;	         				
					number=0;
					break;// End the small loop , Repeat the input operation in the first step 
					}  
			
		}

		
  }		
  while(1)
   {
		if(number3==13||number3==14||number3==15||number3==16)
		{break;}
    number4=jianpan();		 
		if(number3==11){	  
			LCD_ShowChar(2,9,'.');				
	  		   if(number4){ 
						Buzzer_Time(100);
				    if(number4<=10){
							 if(count4<3){// Input at most 3 position , Avoid spillovers 					
										password4=10*password4;// Here two lines are the key , Shift the input single digits in sequence 
										password4=number4%10+password4;										

										if(count4>=0)
										{
										  LCD_ShowNum(2,10,password4,1); 
										}
										if(count4>=1)
										{ 
											LCD_ShowNum(2,10,(password4/10)%10,1);	
										  LCD_ShowNum(2,11,password4,1);
                      										
										}
										if(count4>=2)
										{
										  LCD_ShowNum(2,12,password4,1); 
											LCD_ShowNum(2,11,(password4/10)%10,1); 
											LCD_ShowNum(2,10,(password4/100)%10,1);
										}
								     				                  
							 }
								 count4++;					 				 			 				 			  				  
						} 
				  
					 if(number4==12){
						 
						 if(count2==1) password3=password3*100;// Using overflow variables , Implement a , Data with two decimal places and data with three decimal places are unified 
						 if(count2==2) password3=password3*10;
						 if(count4==1) password4=password4*100;
						 if(count4==2) password4=password4*10;
						 
						switch (symbol){// Integers ( decimal )x decimal 
									case 13:  number=(password1+password3*0.001)+(password2+password4*0.001);  break; 	
									case 14:  number=(password1+password3*0.001)-(password2+password4*0.001);  break;
									case 15:  number=(password1+password3*0.001)*(password2+password4*0.001);  break;
									case 16:  number=(password1+password3*0.001)/(password2+password4*0.001);  break;
									}

									LCD_ShowString(2,1,"result:");
							    LCD_ShowNum(2,8,number,1); 
									LCD_ShowNum(2,7,(unsigned long)(number/10)%10,1); 
									LCD_ShowNum(2,6,(unsigned long)(number/100)%10,1); 
									LCD_ShowNum(2,5,(unsigned long)(number/1000)%10,1); 
									LCD_ShowNum(2,4,(unsigned long)(number/10000)%10,1); 
									LCD_ShowNum(2,3,(unsigned long)(number/100000)%10,1); 
									LCD_ShowNum(2,2,(unsigned long)(number/1000000)%10,1); 
									LCD_ShowNum(2,1,(unsigned long)(number/10000000)%10,1);
									
							    LCD_ShowChar(2,9,'.');		
								  LCD_ShowNum(2,10,(unsigned long)(number*1000)%1000,3);		 

				          }
								  
								 if(number4==13||number4==14||number4==15||number4==16)
								  {
									 if(count2==1) password3=password3*100;// Using overflow variables in continuous operations , Implement a , Data with two decimal places and data with three decimal places are unified 		
									 if(count2==2) password3=password3*10;
									 if(count4==1) password4=password4*100;
									 if(count4==2) password4=password4*10;
             										
									switch (symbol){// Integers ( decimal )x decimal 
									case 13:  number=(password1+password3*0.001)+(password2+password4*0.001);  break; 	
									case 14:  number=(password1+password3*0.001)-(password2+password4*0.001);  break;
									case 15:  number=(password1+password3*0.001)*(password2+password4*0.001);  break;
									case 16:  number=(password1+password3*0.001)/(password2+password4*0.001);  break;
									}
									password1=number;
									symbol=number4;									
									number=0;
									break;// End the small loop , Repeat the input operation in the first step   
									}			
									 

	            }
		
          }

       } 
    }

}

Keyboard entry ：

#include <REGX52.H>
#include "delay.h"
/**
  * @brief   Matrix keyboard 
  * @param   nothing 
  * @retval  Press the key to enter if() and while() in , The moment you release your hand , Return value generation , And return the original function 
	*          When no key is pressed , Returns the initial value 0( Why should the main function add if？ It is used to detect whether the key is pressed , Only press to enter the cycle )
  */
unsigned int jianpan(){
  
	unsigned int number=0;
	
	while(1){
	
	P1=0xFF;// There should be... In front of each column , Otherwise, you will press a number repeatedly , There are other numbers in line with this number 
	P1_3=0;
	if(P1_7==0){delay(20);while(P1_7==0);delay(20);number=1;}
	if(P1_6==0){delay(20);while(P1_6==0);delay(20);number=5;}
	if(P1_5==0){delay(20);while(P1_5==0);delay(20);number=9;}
	if(P1_4==0){delay(20);while(P1_4==0);delay(20);number=13;}
	
	P1=0xFF;
	P1_2=0;
	if(P1_7==0){delay(20);while(P1_7==0);delay(20);number=2;}
	if(P1_6==0){delay(20);while(P1_6==0);delay(20);number=6;}
	if(P1_5==0){delay(20);while(P1_5==0);delay(20);number=10;}
	if(P1_4==0){delay(20);while(P1_4==0);delay(20);number=14;}
	
	P1=0xFF;
	P1_1=0;
	if(P1_7==0){delay(20);while(P1_7==0);delay(20);number=3;}
	if(P1_6==0){delay(20);while(P1_6==0);delay(20);number=7;}
	if(P1_5==0){delay(20);while(P1_5==0);delay(20);number=11;}
	if(P1_4==0){delay(20);while(P1_4==0);delay(20);number=15;}
	
	P1=0xFF;
	P1_0=0;
	if(P1_7==0){delay(20);while(P1_7==0);delay(20);number=4;}
	if(P1_6==0){delay(20);while(P1_6==0);delay(20);number=8;}
	if(P1_5==0){delay(20);while(P1_5==0);delay(20);number=12;}
	if(P1_4==0){delay(20);while(P1_4==0);delay(20);number=16;}


	return number;
  }
}

LCD1602 Show ：

#include <REGX52.H>

// Pin configuration ：
sbit LCD_RS=P2^6;
sbit LCD_RW=P2^5;
sbit LCD_EN=P2^7;
#define LCD_DataPort P0

// Function definition ：
/**
  * @brief  LCD1602 The time delay function ,12MHz Call can be delayed 1ms
  * @param   nothing 
  * @retval  nothing 
  */
void LCD_Delay()
{
	unsigned char i, j;

	i = 2;
	j = 239;
	do
	{
		while (--j);
	} while (--i);
}

/**
  * @brief  LCD1602 Write orders 
  * @param  Command  Command to write 
  * @retval  nothing 
  */
void LCD_WriteCommand(unsigned char Command)
{
	LCD_RS=0;
	LCD_RW=0;
	LCD_DataPort=Command;
	LCD_EN=1;
	LCD_Delay();
	LCD_EN=0;
	LCD_Delay();
}

/**
  * @brief  LCD1602 Writing data 
  * @param  Data  The data to be written 
  * @retval  nothing 
  */
void LCD_WriteData(unsigned char Data)
{
	LCD_RS=1;
	LCD_RW=0;
	LCD_DataPort=Data;
	LCD_EN=1;
	LCD_Delay();
	LCD_EN=0;
	LCD_Delay();
}

/**
  * @brief  LCD1602 Set cursor position 
  * @param  Line  Row position , Range ：1~2
  * @param  Column  Column position , Range ：1~16
  * @retval  nothing 
  */
void LCD_SetCursor(unsigned char Line,unsigned char Column)
{
	if(Line==1)
	{
		LCD_WriteCommand(0x80|(Column-1));
	}
	else if(Line==2)
	{
		LCD_WriteCommand(0x80|(Column-1+0x40));
	}
}

/**
  * @brief  LCD1602 Initialization function 
  * @param   nothing 
  * @retval  nothing 
  */
void LCD_Init()
{
	LCD_WriteCommand(0x38);// Eight bit data interface , Two lines show ,5*7 Lattice 
	LCD_WriteCommand(0x0c);// Show on , The cursor is off , Flashing off 
	LCD_WriteCommand(0x06);// After data reading and writing , The cursor automatically adds one , The picture doesn't move 
	LCD_WriteCommand(0x01);// Cursor reset , Clear the screen 
}

/**
  * @brief   stay LCD1602 Display a character at the specified position 
  * @param  Line  Row position , Range ：1~2
  * @param  Column  Column position , Range ：1~16
  * @param  Char  Characters to display 
  * @retval  nothing 
  */
void LCD_ShowChar(unsigned char Line,unsigned char Column,char Char)
{
	LCD_SetCursor(Line,Column);
	LCD_WriteData(Char);
}

/**
  * @brief   stay LCD1602 Start displaying the given string at the specified position 
  * @param  Line  Start line position , Range ：1~2
  * @param  Column  Start column position , Range ：1~16
  * @param  String  String to display 
  * @retval  nothing 
  */
void LCD_ShowString(unsigned char Line,unsigned char Column,char *String)
{
	unsigned char i;
	LCD_SetCursor(Line,Column);
	for(i=0;String[i]!='\0';i++)
	{
		LCD_WriteData(String[i]);
	}
}

/**
  * @brief   Return value =X Of Y Power 
  */
int LCD_Pow(int X,int Y)
{
	unsigned char i;
	int Result=1;
	for(i=0;i<Y;i++)
	{
		Result*=X;
	}
	return Result;
}

/**
  * @brief   stay LCD1602 Start displaying the given number at the specified position 
  * @param  Line  Start line position , Range ：1~2
  * @param  Column  Start column position , Range ：1~16
  * @param  Number  Number to display , Range ：0~65535
  * @param  Length  The length of the number to display , Range ：1~5
  * @retval  nothing 
  */
void LCD_ShowNum(unsigned char Line,unsigned char Column,unsigned int Number,unsigned char Length)
{
	unsigned char i;
	LCD_SetCursor(Line,Column);
	for(i=Length;i>0;i--)
	{
		LCD_WriteData(Number/LCD_Pow(10,i-1)%10+'0');
	}
}

Buzzer ：

#include <REGX52.H>
#include <INTRINS.H>

// Buzzer port ：
sbit Buzzer=P2^5;

/**
  * @brief   Buzzer private delay function , Time delay 500us
  * @param   nothing 
  * @retval  nothing 
  */
void Buzzer_Delay500us()		//@12.000MHz
{
	unsigned char i;

	_nop_();
	i = 247;
	while (--i);
}

/**
  * @brief   The buzzer makes a sound 
  * @param  ms  The duration of the sound , Range ：0~32767
  * @retval  nothing 
  */
void Buzzer_Time(unsigned int ms)
{
	unsigned int i;
	for(i=0;i<ms*2;i++)//2x500us=1ms
	{
		Buzzer=!Buzzer;
		Buzzer_Delay500us();// Phonation frequency 1000Hz, One cycle time 0.5ms, so 29 Yes ms want *2
		}//f=1/T, One cycle is 2x500us=1ms( A crest and a trough ),f=1/(1x10^-3)=1000Hz
}

The time delay function ：

void delay(unsigned int xms)		//@12.000MHz
{
	unsigned char i, j;
while(xms){
			i = 12;
			j = 169;
			do
			{
				while (--j);
			} while (--i);
     xms--;
		}
}