c51单片机定时器30秒倒计时程序,一个按键控制开始,另一个按键控制暂停和继续

#include
unsigned char code ledtab[]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f,0x40};//0-9
unsigned char sec=30,scanled;
unsigned char disdat[2];
sbit keys=P1^0;
sbit keyc=P1^1;
sbit fmq=P3^0;

void delay(unsigned int x)
{
	unsigned int i,j;
	for(i=0;i	for(j=0;j<120;j++);
}
void dischg()
{
	disdat[0]=sec/10;
	disdat[1]=sec%10;
}
void t0isr() interrupt 1	//秒计时
{
	TH0=0x3c;
	TL0=0xb0;
	time++;
	if(time==20)
	{
		time=0;
		if(sec>0 && flag==0)sec--;
	}
	dischg();
}
void t1isr() interrupt 3	//显示
{
	TH1=0xec;
	TL1=0x78;
	switch(scanled)
	{
		case 0:
			P2=0xfe;
			P0=ledtab[disdat[1]];
			break;
		case 1:
			P2=0xfd;
			P0=ledtab[disdat[0]];
			break;
		default:break;
	}
	scanled++;
	scanled%=2;
}
main()
{
	TMOD=0x11;
	TH0=0x3c;
	TL0=0xb0;
	TH1=0xec;
	TL1=0x78;
	TR1=1;
	TR0=0;
	ET0=1;
	ET1=1;
	EA=1;
	fmq=0;
	scanled=0;
	while(1)
	{
	 if(keys==0)
	 	{
		while(keys==0);
		TR0=1;
		}
	 if(keyc==0)
	 	{
		while(keyc==0);
		TR0=~TR0;
		}
	}
}