独立按键的扫描

1. unsigned char KeyNumber = 0;
2. if(P3_1==0){    //表示如果按键按下
3. Delay(20);    //延时20ms用来消抖
4. while(P3_1==0);    //while空程序，手一直按住按键，程序一直卡在这里，直到松手跳出此循环
5. Delay(20);    //再次延时20ms消抖
6. KeyNumber=1;}    //记录键码值

1. #include <REGX52.H>
2. #include "Delay.h"
3. 
4. 
5. unsigned char Key()
6. {
7.  unsigned char KeyNumber = 0;
8. 
9.  if(P3_1==0){Delay(20);while(P3_1==0);Delay(20);KeyNumber=1;}
10.   if(P3_0==0){Delay(20);while(P3_0==0);Delay(20);KeyNumber=2;}
11.   if(P3_2==0){Delay(20);while(P3_2==0);Delay(20);KeyNumber=3;}
12.   if(P3_3==0){Delay(20);while(P3_3==0);Delay(20);KeyNumber=4;}
13. 
14.   return KeyNumber;
15. }