以下是4x4矩阵用LCD1602显示键值0~9：

/***************************************************************
* 程序名称：4*4矩阵键盘LCD1602显示0~9数
* 实验对象：XY850/XY900_USB型开发板
* 硬件说明：AT89S51/52或STC89C51/52,74HC573组合对数码管控制
* 编       写：月夜听风   更多资料请登陆：http://www.mcusy.cn
****************************************************************/
#include<reg52.h>
#include<LCD1602.h> //
#define uchar unsigned char
#define uint unsigned int
uchar code tab0[] = {" Key Enter :       "};
uchar code tab1[] = {" =                           "}; //显示
sbit BELL=P3^7; //小喇叭
//--------------------------------------------------------------
void de1ms(uchar i) //延时1ms
{
   uchar x,y;
   for(x=0;x<i;x++)
   {for(y=0;y<122;y++){;}}
}
//--------------------------------------------------------------
void BELL_alarm(uint m) //按键音、适合12M,参数m为时长
{  
   uchar y,j;
   for(y=0;y<m;y++)
   {BELL =~ BELL; for(j=0;j<25;j++);} //取反/频率
}
/*---------------------矩阵扫描取值函数----------------------*/
uchar keyscan(void)
{
   uchar scode,rcode;
   P1=0xf0;  //发全0行扫描码，列输入
   if((P1&0xf0)!=0xf0)   //若有键按
       {
           de1ms(10); //消抖
           if((P1&0xf0)!=0xf0) //重测
               {
       scode=0xfe; //逐行扫描初值
                   while((scode&0x10)!=0)
                       {
                           P1=scode;     //输出行扫描码
                           if((P1&0xf0)!=0xf0)   //若本行有键按下
                                 {
                                     rcode=(P1&0xf0)|0x0f;
                                     while((P1&0xf0)!=0xf0); //松手检测(视情况也可去掉这句)
                                     BELL_alarm(200);
                                     return((~scode)+(~rcode)); //返回扫描键代码
                                 }
                           else
                           scode=(scode<<1)|0x01; //此行无键按下、行扫描码左移一位
                         }
               }
       }
   return(0); //无键按下、则返回值为0
}
/*----------------------键值显示函数-------------------------*/
void display(uchar dis)
{
   uchar num;
   switch(dis) //键值比较/选择
       {
           case 0x41: num=0; break; // 0
           case 0x88: num=1; break; // 1
           case 0x48: num=2; break; // 2
           case 0x28: num=3; break; // 3
           case 0x84: num=4; break; // 4
           case 0x44: num=5; break; // 5
           case 0x24: num=6; break; // 6
           case 0x82: num=7; break; // 7
           case 0x42: num=8; break; // 8
           case 0x22: num=9; break; // 9
           default:;break;
       }
   DisplayOne(5,1,num+0x30); //显示/第5位
}

/*-------------------------主函数----------------------------*/
void main(void)
{
   char i; uchar key;
   de1ms(100);
   InitLcd();   //LCD初始化
   for(i=15;i>=0;i--)
       {
           DisplayList(i,0,tab0);//第一行
           DisplayList(i,1,tab1);//第二行
           de1ms(500);    
       }
   de1ms(100);
   while(1)
       {
           key=keyscan(); //键值赋予key
           display(key);   //调用显示
       }
}