单片机99秒倒计时程序

可以通过S0（功能键）,S1（加键）,S2（减键）设定初值，倒数为00-00-00时蜂鸣器响，通过八位LED显示；

#include
#include
#define uchar unsigned char
#define uint unsigned int

uchar code wei[]={0xfe,0xfd,0xfb,0xf7,0xef,0xdf,0xbf,0x7f};//八位位选码表
uchar code duan[]={0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90};//段选码表

sbit s0=P3^3; //设置功能键
sbit s1=P3^5; //设置‘加’键
sbit s2=P3^6; //设置‘减’键
sbit beep=P3^7; //设置蜂鸣器

void delay(uint z);
void display();
void init();
void keyscan();

uchar shi,fen,miao,nam;


void main()
{
init();
while(1)
{
display();
keyscan();
beep=1;
if (miao==0&&fen==0&&shi==0)//当倒数计时为00-00-00时蜂鸣器响
{
beep=0;
TR0=0;
}
}


}

void delay(uint z)
{
uint i,j;
for (i=z;i>0;i--)
for (j=110;j>0;j--);
}

void display() //我这里P2为位选，P0为段选，显示格式为 时-分-秒
{
uchar s,g;
s=shi/10;
g=shi%10;
P2=wei[7];
P0=duan[s];
delay(1);
P2=wei[6];
P0=duan[g];
delay(1);
P2=wei[5];
P0=0xbf;
delay(1);

s=fen/10;
g=fen%10;
P2=wei[4];
P0=duan[s];
delay(1);
P2=wei[3];
P0=duan[g];
delay(1);
P2=wei[2];
P0=0xbf;
delay(1);

s=miao/10;
g=miao%10;
P2=wei[1];
P0=duan[s];
delay(1);
P2=wei[0];
P0=duan[g];
delay(1);
}

void init()
{
miao=10; //设定初值为 00-01-10
fen=1;
shi=0;

EA=1;
ET0=1;
TMOD=0X01;
TH0=(65536-50000)/256;
TL0=(65536-50000)%256;
TR0=1;

}

void timer() interrupt 1
{
TH0=(65536-50000)/256;
TL0=(65536-50000)%256;
nam++;

if (nam==20)
{
nam=0;
if (miao==0)
{
miao=60;
if (fen==0)
{
fen=60;
if (shi==0)
shi=24;
shi--;

}
fen--;

}
miao--;


}



}

void keyscan()
{
uchar key,num;
if (s0==0)
{
delay(5);
if (s0==0)
{
key++;
if (key==4)
key=0;

}
while(!s0)
display();
}

if (s1==0)
{
delay(5);
if (s1==0)
{
num=1;
}
while(!s1)
display();
}

if (s2==0)
{
delay(5);
if (s2==0)
{
num=2;
}
while(!s2)
display();
}

switch(key)
{
case 0:TR0=1;break;
case 1:TR0=0;
if (num==1)
{
num=0;
miao++;
if (miao>=60)
miao=0;
display();
}
if (num==2)
{
num=0;
if (miao==0)
miao=60;
miao--;
display();
}

break;
case 2:
if (num==1)
{
num=0;
fen++;
if (fen>=60)
fen=0;
display();
}
if (num==2)
{
num=0;
if (fen==0)
fen=60;
fen--;
display();

}

break;
case 3:
if (num==1)
{
num=0;
shi++;
if (shi>=24)
s

hi=0;
display();

}
if (num==2)
{
num=0;
if (shi==0)
shi=24;
shi--;
display();
}

break;

}

}倒计时 报警