key.c

按键动态扫描子程序

//KEY1 按下程序开始执行,每三秒换一状态,用LED1指示;
//任何时候按下KEY1都从头执行.
//KEY2 按下暂停程序执行,再次按下继续程序执行.
#include<reg52.h>
sbit key1=P2^0;
sbit key2=P2^1;
sbit led1=P1^7;
sbit led2=P1^6;

void delay_10ms()
{
	unsigned int i;
	for(i=0;i<2500;i++);
}
void main()
{
	unsigned char k;
	led1=1;
rep:
	key1=1;
	while(key1);
	delay_10ms();
	if(key1) goto rep;
	while(~key1);

next:
	led1=(~led1);

  for(k=0;k<100;k++)
  {
	key2=1;
	if(~key2)
	{
		delay_10ms();
		if(key2) goto jump;
		led2=0;
		while(~key2);

rep1:
		key2=1;
		while(key2)
			{
				if(~key1)
				{
					delay_10ms();
					if(~key1)
					{
						led1=1;
						led2=1;
						while(~key1);
						goto next;
					}
				}
			}
		delay_10ms();
		if(key2) goto rep1;
		while(~key2);
		led2=1;
	}
jump:
	delay_10ms();
	if(~key1)
	{
		delay_10ms();
		if(~key1)
		{
			led1=1;
			led2=1;
			while(~key1);
			goto next;
		}
	}

  }
  goto next;
}