07-小蜜蜂单片机矩阵键盘

做题之前要先理解一下按键的内部结构。
矩阵键盘中有两个I/O端口，一个作为输入，一个作为输出。
当按键按下时，两个端口相连导通（我是这样认为的），当作为输入的I/O端口输入高电平时，输出就是高电平，反之就是低电平。
矩阵键盘扫描原理

#include "reg52.h"

unsigned char code SMG_duanma[18]=			   //code 是表格形式
{0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,
 0x80,0x90,0x88,0x80,0xc6,0xc0,0x86,0x8e,
 0xbf,0x7f};

sfr P4 = 0xC0;
 sbit R1 = P3^0;
 sbit R2 = P3^1;
 sbit R3 = P3^2;
 sbit R4 = P3^3;

 sbit C4 = P3^4;
 sbit C3 = P3^5;
 sbit C2 = P4^2;
 sbit C1 = P4^4;
void SelectHC573(unsigned char channel)		 //锁存器选通
{
   switch(channel)
 {
    case 4:
	  P2 = (P2 & 0x1f) | 0x80;
	break;
	case 5:
	  P2 = (P2 & 0x1f) | 0xa0;
	break;
	case 6:
	  P2 = (P2 & 0x1f) | 0xc0;
	break;
	case 7:
	  P2 = (P2 & 0x1f) | 0xe0;
	break;
 }
}

void DisplayKeyNum(unsigned char value)		                      //数码管显示
{
   	 SelectHC573(6);
	 P0 = 0x01;
	 SelectHC573(7);
	 P0 = value;
}
unsigned char key_num;
void ScanKeysMulti()
{
     R1 = 0;
	 R2 = R3 = R4 =1;
	 C1 = C2 = C3 =C4 = 1;
	 if(C1 == 0)
	 {
	   while(C1==0);//判断是否松开
	   key_num = 0;
	   DisplayKeyNum(SMG_duanma[key_num]);
	 }
	 else if (C2==0)
	 {
	  while(C2==0);
	  key_num=1;
	  DisplayKeyNum(SMG_duanma[key_num]);
	 }
	 else if (C3==0)
	 {
	  while(C3==0);
	  key_num=2;
	  DisplayKeyNum(SMG_duanma[key_num]);
	 }
	 else if (C4==0)
	 {
	  while(C4==0);
	  key_num=3;
	  DisplayKeyNum(SMG_duanma[key_num]);
	 }


	 R2 = 0;
	 R1 = R3 = R4 =1;
	 C1 = C2 = C3 =C4 = 1;
	 if(C1 == 0)
	 {
	   while(C1==0);
	   key_num = 4;
	   DisplayKeyNum(SMG_duanma[key_num]);
	 }
	 else if (C2==0)
	 {
	  while(C2==0);
	  key_num=5;
	  DisplayKeyNum(SMG_duanma[key_num]);
	 }
	 else if (C3==0)
	 {
	  while(C3==0);
	  key_num=6;
	  DisplayKeyNum(SMG_duanma[key_num]);
	 }
	 else if (C4==0)
	 {
	  while(C4==0);
	  key_num=7;
	  DisplayKeyNum(SMG_duanma[key_num]);
	 }
	 R3 = 0;
	 R2 = R1 = R4 =1;
	 C1 = C2 = C3 =C4 = 1;
	 if(C1 == 0)
	 {
	   while(C1==0);
	   key_num = 8;
	   DisplayKeyNum(SMG_duanma[key_num]);
	 }
	 else if (C2==0)
	 {
	  while(C2==0);
	  key_num=9;
	  DisplayKeyNum(SMG_duanma[key_num]);
	 }
	 else if (C3==0)
	 {
	  while(C3==0);
	  key_num=10;
	  DisplayKeyNum(SMG_duanma[key_num]);
	 }
	 else if (C4==0)
	 {
	  while(C4==0);
	  key_num=11;
	  DisplayKeyNum(SMG_duanma[key_num]);
	 }
	 R4 = 0;
	 R2 = R3 = R1 =1;
	 C1 = C2 = C3 =C4 = 1;
	 if(C1 == 0)
	 {
	   while(C1==0);
	   key_num = 12;
	   DisplayKeyNum(SMG_duanma[key_num]);
	 }
	 else if (C2==0)
	 {
	  while(C2==0);
	  key_num=13;
	  DisplayKeyNum(SMG_duanma[key_num]);
	 }
	 else if (C3==0)
	 {
	  while(C3==0);
	  key_num=14;
	  DisplayKeyNum(SMG_duanma[key_num]);
	 }
	 else if (C4==0)
	 {
	  while(C4==0);
	  key_num=15;
	  DisplayKeyNum(SMG_duanma[key_num]);
	 }
}
void main()
{
  while(1)
  {
		  ScanKeysMulti();
  }
}

来源：CSDN

作者：......Oops

链接：https://blog.csdn.net/qq_44892126/article/details/103239665