#include<AT89X51.H>
#include<stdio.h>

unsigned char code table[]={0x3f,0x06,0x5b,0x4f,
                            0x66,0x6d,0x7d,0x07,
                            0x7f,0x6f,0x77,0x7c,
                            0x39,0x5e,0x79,0x71};
unsigned char STH0,STL0;
	
unsigned int code music_feq[]={64021,64103,64260,64400,
                          	64524,64580,64684,64777,
                          	64820,64898,64968,65030,
                          	65058,65110,65157,65178};

//*******特別注意要進行預先聲明的工作******************//
void scan_key(void);  
//*****************************************************//
void delay(void);
void proc(unsigned char);
void wait_stop(unsigned char);

void main(void)
{
	TMOD=0x01;
	EA=1;
	ET0=1;
	P3=0xFF;
	scan_key();	
}

void TIME0(void) interrupt 1 using 0
{
	  TH0=STH0;
	  TL0=STL0;
	  P1_0=~P1_0;
}

void scan_key(void)
{
	unsigned char key,temp;
	while(1)
	{
		P3_4=0;
		temp=P3;
		temp&=0x0F;
		if(temp!=0x0F)
		{
			 delay();
			 temp=P3;
			 temp&=0x0F;
			 if(temp!=0x0F)
			 {
			 	switch(temp)
				{
					case 0x0E:
						key=0;
						break;
					case 0x0D:
						key=1;
						break;
					case 0x0B:
						key=2;
						break;
					case 0x07:
						key=3;
						break;
				}
				proc(key);
				wait_stop(temp);
			 }
		}
		//*******如果不是第一排的按鍵被按鍵下則轉入第二排掃描**************//
		P3=0xFF;
		P3_5=0;
		temp=P3;
		temp&=0x0F;
		if(temp!=0x0F)
		{
			delay();
			temp=P3;
			temp&=0x0F;
			if(temp!=0x0F)
			{
				switch(temp)
				{
					case 0x0E:
						key=4;
						break;
					case 0x0D:
						key=5;
						break;
					case 0x0B:
						key=6;
						break;
					case 0x07:
						key=7;
						break;
				}
				proc(key);
				wait_stop(temp);	
			}	
		}
	 //****************第三排按鍵掃描*******************//
	 	P3=0xFF;
		P3_6=0;
		temp=P3;
		temp&=0x0F;
		if(temp!=0x0F)
		{
			delay();
			temp=P3;
			temp&=0x0F;
			if(temp!=0x0F)
			{
				switch(temp)
				{
					case 0x0E:
						key=8;
						break;
					case 0x0D:
						key=9;
						break;
					case 0x0B:
						key=10;
						break;
					case 0x07:
						key=11;
						break;
				}
				proc(key);
				wait_stop(temp);	
			}	
		}
	//*********************第四排掃描*******************//
		P3=0xFF;
		P3_7=0;
		temp=P3;
		temp&=0x0F;
		if(temp!=0x0F)
		{
			delay();
			temp=P3;
			temp&=0x0F;
			if(temp!=0x0F)
			{
				switch(temp)
				{
					case 0x0E:
						key=12;
						break;
					case 0x0D:
						key=13;
						break;
					case 0x0B:
						key=14;
						break;
					case 0x07:
						key=15;
						break;
				}
				proc(key);
				wait_stop(temp);
			}	
		}	
	}
}

void delay(void)
{
	unsigned char i,j;
	for(i=0;i<80;i++)
		for(j=0;j<200;j++);
}

void proc(unsigned char key)
{
	P1_0=~P1_0;
	P0=table[key];
	STH0=music_feq[key]/256;
	STL0=music_feq[key]%256;
	TH0=STH0;
	TL0=STL0;
	TR0=1;
}

void wait_stop(unsigned char temp)
{
		do
		{
			temp=P3;
			temp=0x0F;
		}
		while(temp!=0x0F);
		TR0=0;
}