蓝桥杯单片机组备赛指南请查看 ：本专栏第1篇文章

本文章针对蓝桥杯-单片机组比赛开发板所写，代码可直接在比赛开发板上使用。

型号：国信天长4T开发板（绿板），芯片：IAP15F2K61S2

（使用国信天长蓝板也可以完美兼容，与绿板几乎无差别）

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        恭喜各位看到这里，大势已去，接下来只是额外学习一点省赛的小技巧

1. 功能概览

        大部分省赛里，官方会考察矩阵键盘，就不会考察大家对于长按与短按的操作

        但是一旦遇到考独立按键的试题，就一定会有长短按的考察

        推荐大家掌握定时器方式，短按加1，长按不松手清0方式。其他方式为供大家共同学习，一起进步所写，有任何问题欢迎指出。

2. 代码目的

        按下独立按键S7，数码管两位数显示加1。长按独立按键S7超过1秒，则数码管示数清0。

        性能指标：数码管亮度均匀，最大计数值99

3. 实现思路

        只涉及一个S7按键，因此我们将长短按的检测放到 keyrunning（）按键检测函数中。

        当S7==0，表示按键被按下，我们一个 TR0=1 启动定时器；

        当while( S7 == 0 );循环结束，表示按键被松开，我们一个 TR0=0 停止定时器；

        此时读取定时过程中记录的时间，如果大于1则将显示数值清0.

4. 代码参考

4.1 定时器方式：短按加1，长按不松手清0代码

#include <reg52.h>
#include <intrins.h>

unsigned char code duanma[18]={0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90,
											0x88,0x83,0xc6,0xc0,0x86,0x8e,0xbf,0x7f};

sbit S7 = P3^0;
sbit AUXR = 0x8e;
unsigned char count_num = 0;
											
void SMGrunning ();

void select_HC573 ( unsigned char channal )
{
	switch ( channal )
	{
		case 4:
			P2 = ( P2 & 0x1f ) | 0x80;
		break;
		case 5:
			P2 = ( P2 & 0x1f ) | 0xa0;
		break;
		case 6:
			P2 = ( P2 & 0x1f ) | 0xc0;
		break;
		case 7:
			P2 = ( P2 & 0x1f ) | 0xe0;
		break;
	}
}

void state_SMG ( unsigned char pos_SMG , unsigned char value_SMG )
{
	select_HC573 ( 7 );
	P0 = 0xff;
	
	select_HC573 ( 6 );
	P0 = 0x01 << pos_SMG;
	select_HC573 ( 7 );
	P0 = value_SMG;
}

void state_SMG_all ( unsigned char value_SMG )
{
	select_HC573 ( 6 );
	P0 = 0xff;
	select_HC573 ( 7 );
	P0 = value_SMG;
}

void init_sys ()
{
	select_HC573 ( 4 );
	P0 = 0xff;
	select_HC573 ( 5 );
	P0 = 0x00;	
}

//用定时器0，产生20ms一次的中断
void init_timer0(void)		//20毫秒@11.0592MHz
{
	AUXR &= 0x7F;		//定时器时钟12T模式
	TMOD &= 0xF0;		//设置定时器模式
	TL0 = 0x00;		//设置定时初始值
	TH0 = 0xB8;		//设置定时初始值
	TF0 = 0;		//清除TF0标志
	
	EA = 1;
	ET0 = 1;
}

unsigned char count_20ms = 0;
bit count_1s = 0;
void timer0_service () interrupt 1
{
	TL0 = 0x00;		//设置定时初始值
	TH0 = 0xB8;		//设置定时初始值
	
	count_20ms++;
	
	if ( count_20ms == 50 )
	{
		count_20ms = 0;
		count_1s = 1;
	}
	if ( count_1s == 1 )
	{
		count_num = 0;
	}
}

void Delay2ms()		//@11.0592MHz
{
	unsigned char i, j;

	_nop_();
	_nop_();
	i = 22;
	j = 128;
	do
	{
		while (--j);
	} while (--i);
}


void keyrunning ()
{
	if ( S7 == 0 )
	{
		Delay2ms();//适当消除一点点抖动
		
		if ( S7 == 0 )
		{
			TR0 = 1;
			while ( S7 == 0 )
			{
				SMGrunning ();
			}
			TR0 = 0;
			count_20ms = 0;
			
			if ( count_1s == 1 )
			{
				count_1s = 0;
			}
			else
			{
				count_num ++;
				
				if ( count_num == 100 )
				{
					count_num = 0;
				}
				
			}
		}
	}
}

void SMGrunning ()
{
	state_SMG ( 6 , duanma[count_num/10] );
	Delay2ms();
	state_SMG ( 7 , duanma[count_num%10] );
	Delay2ms();
	
	state_SMG_all ( 0xff );
}

void main ()
{
	init_sys ();
	init_timer0 ();
	
	while( 1 )
	{
		SMGrunning ();
		keyrunning ();
	}
}

4.2 定时器方式：短按加1，长按松手清0代码

        为了节省篇幅，这里我来给讲要怎么修改程序实现：

我们的思路就是，删去中断服务函数中直接响应清0的语句，在按键检测函数中加入清0语句

        步骤一：在中断服务函数timer0_service() 中，注释掉或者删掉这4行代码

        步骤二：在键值扫描函数keyrunning（）中，添加这1行代码：

4.3 延时函数方式：短按加1，长按松手清0代码

思路就是，循环20ms的软件延时，当循环个数达到50个时，则表示时间经过了1s

        代码如下：

#include <reg52.h>
#include <intrins.h>

unsigned char code duanma[18]={0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90,
											0x88,0x83,0xc6,0xc0,0x86,0x8e,0xbf,0x7f};

sbit S7 = P3^0;
sbit AUXR = 0x8e;
											
unsigned char count_num = 0;
unsigned char count_20ms = 0;
											
void SMGrunning ();

void select_HC573 ( unsigned char channal )
{
	switch ( channal )
	{
		case 4:
			P2 = ( P2 & 0x1f ) | 0x80;
		break;
		case 5:
			P2 = ( P2 & 0x1f ) | 0xa0;
		break;
		case 6:
			P2 = ( P2 & 0x1f ) | 0xc0;
		break;
		case 7:
			P2 = ( P2 & 0x1f ) | 0xe0;
		break;
	}
}

void state_SMG ( unsigned char pos_SMG , unsigned char value_SMG )
{
	select_HC573 ( 7 );
	P0 = 0xff;
	
	select_HC573 ( 6 );
	P0 = 0x01 << pos_SMG;
	select_HC573 ( 7 );
	P0 = value_SMG;
}

void state_SMG_all ( unsigned char value_SMG )
{
	select_HC573 ( 6 );
	P0 = 0xff;
	select_HC573 ( 7 );
	P0 = value_SMG;
}

void init_sys ()
{
	select_HC573 ( 4 );
	P0 = 0xff;
	select_HC573 ( 5 );
	P0 = 0x00;	
}

void Delay2ms()		//@11.0592MHz
{
	unsigned char i, j;

	_nop_();
	_nop_();
	i = 22;
	j = 128;
	do
	{
		while (--j);
	} while (--i);
}

//数码管刷新函数自带4ms，因此这里我们设置16ms
void Delay16ms()		//@11.0592MHz
{
	unsigned char i, j;

	_nop_();
	_nop_();
	_nop_();
	i = 173;
	j = 28;
	do
	{
		while (--j);
	} while (--i);
}

void keyrunning ()
{
	if ( S7 == 0 )
	{
		Delay2ms();//适当消除一点点抖动
		
		if ( S7 == 0 )
		{
			while ( S7 == 0 )
			{
				SMGrunning ();//数码管扫描函数内自带4ms
				Delay16ms();
				count_20ms++;
				
				if( count_20ms > 50 )
				{
					count_num = 99;
					count_20ms = 50;
				}
			}
			count_20ms = 0;
			count_num ++;
				
			if ( count_num == 100 )
			{
				count_num = 0;
			}
				
		}
	}
}

void SMGrunning ()
{
	state_SMG ( 6 , duanma[count_num/10] );
	Delay2ms();
	state_SMG ( 7 , duanma[count_num%10] );
	Delay2ms();
	
	state_SMG_all ( 0xff );
}

void main ()
{
	init_sys ();
	
	while( 1 )
	{
		SMGrunning ();
		keyrunning ();
	}
}