get_key.h

简单菜单程序,八个按键.使用AVR单片机.2008/3/24--2008/3/29 编译器为ICCAVR7.14.晶振7.3728M,单片机为ATmega16(用ATmega32在proteus中仿

/**********************************************************************************/
//写一个八个按键的程序.最后的两个按键为方向键,可以连续调整.
#define nullkey 0
#define pr_timekey 9
#define nusekey 10

uchar get_key(void)
{
	uchar pass,kcodebuf;	
	static uchar lastkcode,keytime=0;	//定义为静态变量,外部不可见,但需要常驻内存.
	static uchar havekey=0;
	static uchar keylock=0;
		
	kcodebuf=PIND & 0xff;
	keytime++;
	if (kcodebuf!=lastkcode) keytime=0;
	if (kcodebuf==0xff)
	{
		havekey=0;
		keylock=0;
		keytime=0;
		pass=0;
	}
	else if (kcodebuf==0x7f)
	{
		keylock=1;
		if (keytime==0) pass=7;
		else
		{
			if (keytime==100)
			{
				pass=7;
				keytime=80;
			}
			else pass=pr_timekey;
		}
	}
	else if (kcodebuf==0xbf)
	{
		keylock=1;
		if (keytime==0) pass=8;
		else if (keytime==100)
		{
			pass=8;
			keytime=80;
		}
		else pass=pr_timekey;
	}
	
	else if (havekey==0)
	{
		havekey=1;
		pass=nusekey;
	}
	
	else if (keylock==1) pass=nusekey;
	
	else if (kcodebuf==0xdf)
	{
		keylock=1;
		pass=6;
	}
	else if (kcodebuf==0xef)
	{
		keylock=1;
		pass=5;
	}
	else if (kcodebuf==0xf7)
	{
		keylock=1;
		pass=4;
	}
	else if (kcodebuf==0xfb)
	{
		keylock=1;
		pass=3;
	}
	else if (kcodebuf==0xfd)
	{
		keylock=1;
		pass=2;
	}
	else if (kcodebuf==0xfe)
	{
		keylock=1;
		pass=1;
	}
	else pass=nusekey;
	lastkcode=kcodebuf;

	return(pass);
}