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//********"鍵盤及其顯示"**************
//"當(dāng)按下一個鍵的時候顯示按下鍵的鍵值，其余時間顯示字母“P”"
// "P1口作為數(shù)碼管的位選，P0口作為數(shù)碼管的段選"
//"P2口是鍵盤連接口，低4位為列，高4位為行"
#include"reg52.h"
//"下面為數(shù)碼管顯示碼"
unsigned char code table[19]={0x3f,0x06,0x5b,0x4f,0x66,//0~4
0x6d,0x7d,0x07,0x7f,0x6f,//5~9
0x77,0x7c,0x39,0x5e,0x79,//A~E
0x71,0x73,0xc3,0x00};//F.p.=..
unsigned char key_scan(void);
//*************"鍵盤顯示"********************
//"函數(shù)名稱：void key_display(void)"
//"函數(shù)功能：顯示所按下鍵的鍵值"
//"參數(shù)說明：無 P0口作為段碼， P1作為位碼"
//******************************************
void key_display(void)
{
unsigned char key_value_1=16;
P1=0x00;//"選通所有的數(shù)碼管"
key_value_1=key_scan();//"返回鍵值"
P0=table[key_value_1];//"輸出顯示碼"
}
//***********"延時"*********************
//"函數(shù)名稱：void delay(unsigned char delay_time)"
//"函數(shù)功能：延時"
//"參數(shù)說明：有 delay_time"
//*************************************
void delay(unsigned int delay_time)
{
while(delay_time){delay_time--;}
//"延時8+6*delay_time us"
}
//***********"按鍵掃描"*******************
//"函數(shù)名稱：unsigned char key_scan(void)"
//"函數(shù)功能：用行列掃描方式進(jìn)行鍵盤掃描,P2口高四位作為行，低四位作為列"
//"參數(shù)說明：無"
//***************************************
unsigned char key_scan(void)
{
unsigned char key_code;//"鍵盤行編碼"
unsigned char key_value;//"鍵值"
unsigned char row=0;//"行值"
unsigned char line=0;//"列值"
unsigned char temp=0xfe;//"列掃描碼"
unsigned char i;
P2=0xf0;//"P2口賦初值，準(zhǔn)備進(jìn)行行，列掃描"
if((P2&0xf0)!=0xf0)//"表示有鍵按下"
{
delay(2000);//"延時10ms消抖"
if((P2&0xf0)!=0xf0)//"表明確實(shí)有鍵按下，進(jìn)行鍵盤掃描"
{
for(i=0;i<4;i++)//"列掃描"
{
P2=temp;//"送列掃描碼"
if((P2&0xf0)!=0xf0)
{
key_code=P2&0xf0;//"得出行編碼"
row=i;//"計(jì)算出列值"
break;
}
temp=(temp<<1)|0x01;//"進(jìn)行下一列掃描"
}
switch(key_code)//"根據(jù)行編碼得出行值"
{
case 0xe0: line=0;break;
case 0xd0: line=1;break;
case 0xb0: line=2;break;
case 0x70: line=3;break;
default: ;
}
key_value=row*4+line;//"根據(jù)行，列值計(jì)算出鍵值"
}
return(key_value);
while((P2&0xf0)!=0xf0){key_display();}//"等待按鍵釋放"
}
}
//**************"主函數(shù)"***********************
//"函數(shù)名稱：void main(void)"
//"函數(shù)功能："
//"參數(shù)說明：無"
//********************************************
void main(void)
{
while(1)
{
key_display();
}
}
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