代码段

#include <REGX52.H>
#include"LCD1602.h"
#include"DELAY.H"
#include"MatrixKey.h"

unsigned char KeyNum;
unsigned int Password,count;

void main()
{
    LCD_Init();//初始化
	LCD_ShowString(1,1,"Passwordid");
		while(1)
		{
            KeyNum=MatrixKey();
			if(KeyNum)
			{
				if(KeyNum<=10)//如果s1-s10按键按键按下，输入密码
				{
					
					if(count<4)//如果小于四
					{
						Password*=10;//相等于密码左移一位
						Password=KeyNum%10;
						count++;//几次加一
					}
					
				    LCD_ShowNum(2,1,Password,4);
			}
				if(KeyNum==11)//如果s11按下，确认
				{
				if(Password==2345)
				 {
					LCD_ShowString(1,14,"OK ");//显示OK
					Password=0;//密码清零
					count=0;//计次清零
					LCD_ShowNum(2,1,Password,4);
				 }
				else
				  {
					LCD_ShowString(1,14,"eorr");
					Password=0;
					count=0;
					LCD_ShowNum(2,1,Password,4);
					
				  }
				}
				if(KeyNum==12)//如果s12按下,取消
				{	
					Password=0;//密码清零
					count=0;//计次清零
					LCD_ShowNum(2,1,Password,4);;//更新显示
				}
		  }
     }
}

矩阵键盘扫描

#include <REGX52.H>
#include"DELAY.H"
/*
矩阵键盘扫描
KeyNumber 按下按键读取键码1值

*/
unsigned char MatrixKey()
{
unsigned char KeyNumber=0;//矩阵扫描
	P1=0xFF;
	P1_3=0;//相当于四行独立按键
	if(P1_7==0){Delay(20);while(P1_7==0);Delay(20);KeyNumber=1;}
	if(P1_6==0){Delay(20);while(P1_6==0);Delay(20);KeyNumber=5;}
	if(P1_5==0){Delay(20);while(P1_5==0);Delay(20);KeyNumber=9;}
	if(P1_4==0){Delay(20);while(P1_4==0);Delay(20);KeyNumber=13;}
	
	P1=0xFF;
	P1_2=0;
	if(P1_7==0){Delay(20);while(P1_7==0);Delay(20);KeyNumber=2;}
	if(P1_6==0){Delay(20);while(P1_6==0);Delay(20);KeyNumber=6;}
	if(P1_5==0){Delay(20);while(P1_5==0);Delay(20);KeyNumber=10;}
	if(P1_4==0){Delay(20);while(P1_4==0);Delay(20);KeyNumber=14;}
	
	P1=0xFF;
	P1_1=0;
	if(P1_7==0){Delay(20);while(P1_7==0);Delay(20);KeyNumber=3;}
	if(P1_6==0){Delay(20);while(P1_6==0);Delay(20);KeyNumber=7;}
	if(P1_5==0){Delay(20);while(P1_5==0);Delay(20);KeyNumber=11;}
	if(P1_4==0){Delay(20);while(P1_4==0);Delay(20);KeyNumber=15;}
	
	P1=0xFF;
	P1_0=0;
	if(P1_7==0){Delay(20);while(P1_7==0);Delay(20);KeyNumber=4;}
	if(P1_6==0){Delay(20);while(P1_6==0);Delay(20);KeyNumber=8;}
	if(P1_5==0){Delay(20);while(P1_5==0);Delay(20);KeyNumber=12;}
	if(P1_4==0){Delay(20);while(P1_4==0);Delay(20);KeyNumber=16;}
	

	return KeyNumber;

}

MatrixKey.h

#ifndef __MATRIXKEY_H__
#define __MATRIXKEY_H__

unsigned char MatrixKey();

#endif