Preface

The four articles in the series are the four learning records I have written since I started learning microcontrollers. After understanding the above knowledge, I have also mastered some of the programming ideas of the 80C51 microcontroller. Of course, the 80C51 can mount many different chips and devices, and there is still a lot to learn. For now, I have a basic understanding of the use of I/O devices, and I usually write programs while learning, which makes my small goal - Make a calculator , I have a certain foundation. So I took advantage of the time today to record the process of implementing this calculator.

[51 single-chip microcomputer] matrix keyboard line-by-line scanning method simulation experiment + ultra-detailed Proteus simulation and Keil operation steps and [51 single-chip microcomputer] seven-segment digital tube display experiment + detailed explanation , which will not be repeated here.

2. Software Program

Most of the program is similar to the line reversal method + dynamic display program. The main changes are the keyboard scanning program and the display program, and some codes are optimized. The following are the changed parts.

The code is as follows:

1) Initialization

#include

int ans=0;

int newnum=0;

char op='';

int b[4]={12,12,12,0};

int cs[4]={0x07,0x0B,0x0D,0x0E};

int digit[13]={0x3f,0x06,0x5B,0x4f,0x66,0x6D,0x7D,0x07,0x7f,0x6f,0x71,0x40,0x00}; //Display 0~9, 'F', '-' and no display on the digital tube

int p1line[4]={0xf7,0xfb,0xfd,0xfe}; //The row value of the keyboard in the progressive scanning method

2) Main program (keyboard scanning program)

void main(void){

unsigned int key1=0;

unsigned int key2=0;

unsigned int key=0;

int i;

show(0);

while (1){

key=key1=key2=0;

P1=0xf0;

key1=P1&0xf0;

if(key1!=0xf0){

delayms(1);

for(i=0;i<4;i++){

P1=p1line[i];

key2=P1&0xf0;

if(key2!=0xf0){

key=(p1line[i]&0x0f)|key1;

break;

}

}

while((P1&0xf0)!=0xf0);

act(key);

}

}

}

3) Define the function of the button

void act(){

switch(key){

case 0x77:clear();turnLight();break;//clear key, clear + marquee

case 0xB7:savenum(0);break;//Press number 0, save number 0

case 0xD7:output();break;//Press the equal sign to output the result

case 0xE7:saveop('+');break;//Press the operator and save the symbol

case 0x7B:savenum(1);break;

case 0xBB:savenum(2);break;

case 0xDB:savenum(3);break;

case 0xEB:saveop('-');break;

case 0x7D:savenum(4);break;

case 0xBD:savenum(5);break;

case 0xDD:savenum(6);break;

case 0xED:saveop('*');break;

case 0x7E:savenum(7);break;

case 0xBE:savenum(8);break;

case 0xDE:savenum(9);break;

case 0xEE:saveop('/');break;

}

}

4) Other functions

The main programs are the main program, keyboard scanning program, interrupt service program and key function configuration function. Other functions can be modified according to your needs.

① Delay program: