矩阵键盘的模块原理图：

功能：按下矩阵按键，在LCD上显示对应的数值。
采用模块化编程，在此只给出MatrixKey.c 和 main.c 两部分代码

#include <REGX52.H>
#include "Delay.h"/*矩阵键盘读取键码按下不放，会停留在此函数，松开时返回数值，不按返回零
*/
unsigned char Matrixkey()
{unsigned char KeyNum = 0;P1 = 0xFF;P1_3 = 0;if(P1_7 == 0) {Delay(20); while(P1_7 == 0); Delay(20); KeyNum = 1;}if(P1_6 == 0) {Delay(20); while(P1_6 == 0); Delay(20); KeyNum = 5;}if(P1_5 == 0) {Delay(20); while(P1_5 == 0); Delay(20); KeyNum = 9;}if(P1_4 == 0) {Delay(20); while(P1_4 == 0); Delay(20); KeyNum = 13;}P1 = 0xFF;P1_2 = 0;if(P1_7 == 0) {Delay(20); while(P1_7 == 0); Delay(20); KeyNum = 2;}if(P1_6 == 0) {Delay(20); while(P1_6 == 0); Delay(20); KeyNum = 6;}if(P1_5 == 0) {Delay(20); while(P1_5 == 0); Delay(20); KeyNum = 10;}if(P1_4 == 0) {Delay(20); while(P1_4 == 0); Delay(20); KeyNum = 14;}P1 = 0xFF;P1_1 = 0;if(P1_7 == 0) {Delay(20); while(P1_7 == 0); Delay(20); KeyNum = 3;}if(P1_6 == 0) {Delay(20); while(P1_6 == 0); Delay(20); KeyNum = 7;}if(P1_5 == 0) {Delay(20); while(P1_5 == 0); Delay(20); KeyNum = 11;}if(P1_4 == 0) {Delay(20); while(P1_4 == 0); Delay(20); KeyNum = 15;}P1 = 0xFF;P1_0 = 0;if(P1_7 == 0) {Delay(20); while(P1_7 == 0); Delay(20); KeyNum = 4;}if(P1_6 == 0) {Delay(20); while(P1_6 == 0); Delay(20); KeyNum = 8;}if(P1_5 == 0) {Delay(20); while(P1_5 == 0); Delay(20); KeyNum = 12;}if(P1_4 == 0) {Delay(20); while(P1_4 == 0); Delay(20); KeyNum = 16;}return KeyNum;
}

这里要注意必须先判断KeyNum是否为0，否则while不断循环会不断显示0，导致看不到按下按钮显示的数字

#include <REGX52.H>
#include "Delay.h"
#include "LCD1602.h"
#include "MatrixKey.h"unsigned char KeyNum;void main()
{LCD_Init();LCD_ShowString(1, 1, "HelloWorld");while(1){KeyNum = MatrixKey();if(KeyNum) LCD_ShowNum(2, 1, KeyNum, 2);}
}

要利用写好的矩阵键盘来制作一个密码锁，只需要调用MatrixKey文件来直接使用即可，以下是一个简单的密码锁，还有一些bug，不过可以满足基本需求

#include <REGX52.H>
#include "Delay.h"
#include "LCD1602.h"
#include "MatrixKey.h"unsigned char KeyNum;
unsigned int Password, Count;void main()
{LCD_Init();LCD_ShowString(1, 1, "PassWord");while(1){KeyNum = MatrixKey();if(KeyNum){if(KeyNum <= 10) //数字{if(Count < 4){Password *= 10;Password += (KeyNum % 10);Count ++; //输入次数，最多为4}LCD_ShowNum(2, 1, Password, 4); //更新显示}if(KeyNum == 11) //确认键{if(Password == 1234) //如果等于正确密码{LCD_ShowString(1, 14, "OK"); //密码正确Password = 0;Count = 0;LCD_ShowNum(2, 1, Password, 4); //更新显示}else{LCD_ShowString(1, 14, "ERR"); //密码错误Password = 0;Count = 0;LCD_ShowNum(2, 1, Password, 4); //更新显示}}if(KeyNum == 12) //取消键{Password = 0;Count = 0;LCD_ShowNum(2, 1, Password, 4); //更新显示}}}
}