indep_key.c

51单片机及其C语言程序开发实例光盘资料.rar

#include "reg51.h"

void Delay(unsigned int i)
{
	unsigned int j;
	for(;i>0;i--)
		for(j=0;j<100;j++);
	}

void IO_Init()
{
	P1 = 0xff;
	P2 = 0xff;
	}
	
void main()
{
	unsigned char temp,key;
	IO_Init();
	while(1)
	{
		temp = ((P1 & 0x0f) << 4) |(P2 &0x0f);
		if(temp!=0xff)
		{
			Delay(5);
			key = ~(temp &(((P1 & 0x0f) << 4) |(P2 &0x0f)));
			}
		}
	}