基于C51单片机的按键扫描

#include<reg51.h> unsigned char keyscan(void); unsigned char key_num; unsigned char a,b,c; unsigned char code table[]={0xc0,0xf9,0xa4,0xb0, 0x99,0x92,0x82,0xf8, 0x80,0x90,0x88,0x83, 0xc6,0xa1,0x86,0x8e}; void delay(unsigned int z)//1ms延时函数 { unsigned int i,j; for(i=z;i>0;i--) for(j=110;j>0;j--); } void main() { P0=table[1]; while(1) { key_num=keyscan();//按键扫描 P0=table[key_num];//按键显示 } } unsigned char keyscan(void) { P1=0xF0; if((P1&0xF0)!= 0xF0)//按键检测 { delay(10);//按键消抖 if((P1&0xF0)!= 0xF0) { a=0xFE; b=0; c=4; while((a&0x10)!=0) { P1=a; if((P1&0xF0)!= 0xF0) { switch(P1&0xF0) { case 0xE0:c--; case 0xD0:c--; case 0xB0:c--; case 0x70:c--; default:break; } return(b*4+c);//返回键值 } else { a=(a<<1)|0x1;b++;//下一次循环扫描 } } } } return(b*4+c);//松开按键后保留键值 }