key.c

52单片机开发板的实例程序

#include<reg52.h>
#define uint unsigned int
#define uchar unsigned char 
sbit a=P1^0;
sbit b=P1^1;
sbit c=P1^2;
sbit key1=P3^2;
sbit key2=P3^3;
sbit key3=P3^4;
sbit key4=P3^5;
const uchar table[]={
          0x3f,0x06,0x5b,0x4f,0x66,
          0x6d,0x7d,0x07,0x7f,0x6f};
uchar num=0;
void delay(uint k)
{
  uint i;
  for(;k>0;k--)
  for(i=110;i>0;i--);
}
void display()
{
  a=0;b=0;c=0;
  P2=table[num];
}
void main()
{
   while(1)
{
  if(key1==0)
  {
    delay(2);
    if(key1==0)
    {
    while(!key1);
    num=1; 
    }
  }
if(key2==0)
  {
    delay(2);
   if(key2==0)
   {
    while(!key2);
    num=2;
   } 
  }
if(key3==0)
  {
    delay(2);
    if(key3==0)
    {
    while(!key3);
    num=3; 
    }
  }
if(key4==0)
  {
    delay(2);
    //if(key4==0)
    //{
    while(!key4);
    num=4; 
    //}
  }
 display();
}
}