#include  
#include                     
#define uchar unsigned char 

#define uint  unsigned int 

sbit BEEP = P3^7;          //蜂鳴器驅動線 
uchar  dis_buf;            //顯示緩存 
uchar  temp; 
uchar  key;                //鍵順序嗎 

void beep();               //蜂鳴器 
void delay0(uchar x);      //x*0.14MS 

sbit LCD_RS = P2^0;              
sbit LCD_RW = P2^1; 
sbit LCD_EN = P2^2; 

uchar code  cdis1[ ] = {"   KEY NUMBER   "}; 
uchar code  cdis2[ ] = {"  KEY-CODE:   H "}; 

#define delayNOP(); {_nop_();_nop_();_nop_();_nop_();}; 

/*************************************************************/ 
/*                                                           */ 
/* 延時子程序                                                */ 
/*                                                           */ 
/*************************************************************/ 

void  delay(uchar x) 
{ uchar j; 
    while((x--)!=0) 
    { for(j=0;j<125;j++) 
         {;} 
    } 
} 

/*************************************************************/ 
/*                                                           */ 
/*檢查LCD忙狀態                                              */ 
/*lcd_busy為1時，忙，等待。lcd-busy為0時,閑，可寫指令與數據  */ 
/*                                                           */ 
/*************************************************************/  

bit lcd_busy() 
 {                           
    bit result; 
    LCD_RS = 0; 
    LCD_RW = 1; 
    LCD_EN = 1; 
    delayNOP(); 
    result = (bit)(P0&0x80); 
    LCD_EN = 0; 
    return(result);  
 } 

/*******************************************************************/ 
/*                                                                 */ 
/*寫指令數據到LCD                                                  */ 
/*RS=L，RW=L，E=高脈沖，D0-D7=指令碼。                             */ 
/*                                                                 */ 
/*******************************************************************/ 

void lcd_wcmd(uchar cmd) 

{                           
   while(lcd_busy()); 
    LCD_RS = 0; 
    LCD_RW = 0; 
    LCD_EN = 0; 
    _nop_(); 
    _nop_();  
    P0 = cmd; 
    delayNOP(); 
    LCD_EN = 1; 
    delayNOP(); 
    LCD_EN = 0;   
} 

/*******************************************************************/ 
/*                                                                 */ 
/*寫顯示數據到LCD                                                  */ 
/*RS=H，RW=L，E=高脈沖，D0-D7=數據。                               */ 
/*                                                                 */ 
/*******************************************************************/ 

void lcd_wdat(uchar dat) 
{                           
   while(lcd_busy()); 
    LCD_RS = 1; 
    LCD_RW = 0; 
    LCD_EN = 0; 
    P0 = dat; 
    delayNOP(); 
    LCD_EN = 1; 
    delayNOP(); 
    LCD_EN = 0;  
} 

/*************************************************************/ 
/*                                                           */ 
/*  LCD初始化設定                                            */ 
/*                                                           */ 
/*************************************************************/ 

void lcd_init() 
{  
    delay(15);                    
    lcd_wcmd(0x38);      //16*2顯示，5*7點陣，8位數據 
    delay(5); 
    lcd_wcmd(0x38);          
    delay(5); 
    lcd_wcmd(0x38);          
    delay(5); 

    lcd_wcmd(0x0c);      //顯示開，關光標 
    delay(5); 
    lcd_wcmd(0x06);      //移動光標 
    delay(5); 
    lcd_wcmd(0x01);      //清除LCD的顯示內容 
    delay(5); 
} 

/*************************************************************/ 
/*                                                           */ 
/*  設定顯示位置                                             */ 
/*                                                           */ 
/*************************************************************/ 

void lcd_pos(uchar pos) 
{                           
  lcd_wcmd(pos | 0x80);  //數據指針=80+地址變量 
} 

/*************************************************************/ 
/*                                                           */ 
/* 鍵掃描子程序                                              */ 
/*                                                           */ 
/*************************************************************/ 

 void  keysCAN(void) 
 {  
    P1=0x0F;                 //低四位輸入   
    delay(1); 
    temp=P1;                 //讀P1口  
    temp=temp&0x0F; 
    temp=~(temp|0xF0); 
    if(temp==1) 
        key=0; 
    else if(temp==2) 
        key=1; 
    else if(temp==4) 
        key=2; 
    else if(temp==8) 
        key=3; 
    else 
        key=16; 
         
    P1=0xF0;                //高四位輸入 
    delay(1); 
    temp=P1;                //讀P1口        
    temp=temp&0xF0; 
    temp=~((temp>>4)|0xF0); 
    if(temp==1) 
        key=key+0; 
    else if(temp==2) 
        key=key+4; 
    else if(temp==4) 
        key=key+8; 
    else if(temp==8) 
        key=key+12; 
    else 
        key=16; 
         
     dis_buf = key;                 //鍵值入顯示緩存 
     dis_buf = dis_buf & 0x0f; 
  
     if(dis_buf>9)               //轉換為ASCII碼 
      dis_buf = dis_buf+0x37; 
     else 
      dis_buf = dis_buf+0x30; 
 } 

/*************************************************************/ 
/*                                                           */ 
/*判斷鍵是否按下                                             */ 
/*                                                           */ 
/*************************************************************/ 

 void  keydown(void) 
 {   
      P1=0xF0; 
    if(P1!=0xF0) 
    { 
      keyscan(); 
      beep(); 
    } 
 } 

/*************************************************************/ 
/*                                                           */ 
/* 蜂鳴器響一聲                                              */ 
/*                                                           */ 
/*************************************************************/ 

void beep() 
{ 
  unsigned char i; 
  for (i=0;i<100;i++) 
   { 
   delay0(4); 
   BEEP=!BEEP;       //BEEP取反 
   }  
   BEEP=1;           //關閉蜂鳴器 
   delay(250);       //延時      
} 

/*************************************************************/ 
/*                                                           */ 
/* 延時 x*0.14ms                                             */ 
/*                                                           */ 
/*************************************************************/ 
void delay0(uchar x)     
{ 
 unsigned char i; 
  while(x--) 
 { 
  for (i = 0; i<13; i++) {} 
 } 
} 
/*************************************************************/ 
/*                                                           */ 
/* 主程序                                                    */ 
/*                                                           */ 
/*************************************************************/  
    main() 
 { 
    uchar m; 
    P0=0xFF;                    //置P0口 
    P2=0xFF;                    //置P2口   
    delay(10);                 //延時 
    lcd_init();                //初始化LCD              
         
    lcd_pos(0);                //設置顯示位置為第一行的第1個字符 
     m = 0; 
    while(cdis1[m] != ’\0’) 
     {                         //顯示字符 
       lcd_wdat(cdis1[m]); 
       m++; 
     } 

    lcd_pos(0x40);             //設置顯示位置為第二行第1個字符 
     m = 0; 
    while(cdis2[m] != ’\0’) 
     { 
       lcd_wdat(cdis2[m]);      //顯示字符 
       m++; 
     }        
      dis_buf = 0x2d;          //顯示字符"-" 

    while(1) 
    {  
       keydown(); 
       lcd_pos(0x4c);              
       lcd_wdat(dis_buf);        //第一位數顯示    
    } 
  }    

/************************************************************/   

1602液晶顯示按鍵鍵值程序