[嵌入式]c51单片机 独立按键

用独立按键实现按一个按键时，数字从F到0递减的变化程序，即每按一次按键，数码管显示字符减一，减到0后重新显示。

#include <reg52.h>

sbit ADDR0= P2^2;
sbit ADDR1=P2^3;
sbit ADDR2=P2^4;

sbit key1=P3^0;

unsigned char code ledchar[] = {0x00,0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,
0xf8,0x80,0x90,0x88,0x83,0xc6,0xa1,0x86,0x8e};

bit keysta = 1;

void main()
{
	bit backup = 1;
	unsigned char cnt = 16;

	EA  = 1;
	
	ADDR2 =0;
	ADDR1= 0;
	ADDR0 = 0;
	TMOD = 0X01;
	TH0 = 0XF8;
	TL0 = 0XCD;
	ET0 = 1;
	TR0 = 1;
	P0 = ~ledchar[cnt];

	while(1)
	{
		if(keysta != backup)
		{
			if(backup == 0)
			{
				cnt--;
				if(cnt < 1)
				{
				cnt = 16;
				}
				P0 = ~ledchar[cnt];
				}
				backup  = keysta;
				}
				}
				}

void InterruptTimer0() interrupt 1
{
	static unsigned char keybuf = 0xff;
	
	TH0 = 0XF8;
	TL0 = 0XCD;
	
	keybuf = (keybuf <<1)|key1;
	if(keybuf == 0x00)
	{
		keysta = 0;
		}
		else if(keybuf == 0xff)
		{
		keysta = 1;
		}
		else
		{}
		}