基于51单片机设计的简易电子琴

#include <reg51.h> 
#define uint unsigned int 
#define uchar unsigned char
#define output P1
#define input P1
//方便移植在其他电路板上，我的电路使用P1口做键盘输入接口
//定义16个按键
enum KEY{key0,key1,key2,key3,key4,key5,key6,key7,key8,key9,key10,key11,key12,key13,key14,key15};
uchar code table[]={				  //数组定义,显示数码管
	    0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,
	    0x7f,0x6f,0x77,0x7c,0x39,0x5e,0x79,0x71,0x00};
unsigned int code Freqtab[] = { 	//定时半周期的初始值
     64021,64103,64260,64400,      //低音3 4 5 6
     64524,64580,64684,64777,      //低音7,中音1 2 3
     64820,64898,64968,65030,      //中音4 5 6 7
     65058,65110,65157,65178};     //高音1 2 3 4
uint FreqTemp;
//蜂鸣器声音不怎么样，我们使用扬声器，接P3.7口
sbit SPEAK = P3^7;
void delay1ms(uint n)   //误差 0us ,延时n毫秒
{
    uint a,b,c;
	for(c=n;c>0;c--)
    	for(b=199;b>0;b--)
        	for(a=1;a>0;a--);
}

uint key_input(void)
{
	uchar temp1,temp2;			//临时保存读取的行或者列
	uchar num = 16;			   	//返回按键的值
	output = 0x0f;		
   	temp1 = input;				//先读取行
	if(0x0f != temp1)   		//按键按下
	{				   	
		delay1ms(5);			//延时，消除抖动
		temp1 = input;			//再次读取行
		if(0x0f != temp1)		//说明按键确实按下	
		{
			temp1 = temp1 & 0x0f;	//保留低4位
			output = 0xf0;			//准备读取列
			delay1ms(1);			//延时一下，防止下一句读不到
			temp2 = input;			//直接读取列
			temp2 = temp2 & 0xf0;	//保留高4位
			temp1 = temp1 | temp2;	//将temp1和temp2的值合并
		}
	}
	switch(temp1)
	{
		case 0xee:num=0;break;  
        case 0xde:num=1;break;  
        case 0xbe:num=2;break;   
        case 0x7e:num=3;break; 
		case 0xed:num=4;break;               
        case 0xdd:num=5;break;           
        case 0xbd:num=6;break;             
        case 0x7d:num=7;break;   
		case 0xeb:num=8;break;    
        case 0xdb:num=9;break;    
        case 0xbb:num=10;break;   
        case 0x7b:num=11;break;    
		case 0xe7:num=12;break;   
        case 0xd7:num=13;break;   
        case 0xb7:num=14;break;    
        case 0x77:num=15;break;      
		default:break;
	}
	return num;
}
void T0_INT(void) interrupt 1
{
     TL0 = FreqTemp;                //载入定时半周期的初始值
     TH0 = FreqTemp >> 8;
     SPEAK = ~SPEAK;                    //发音
} 
int main()
{
	TMOD = 0X01;		//定时器T0设置为方式1
	EA = 1;
	ET0 = 1;
	TR0 = 0;
	while(1)
	{
		uint num,temp;
		num = key_input();
		temp = num;
		P0 = table[num];
		if(16 != num)
		{
			FreqTemp = Freqtab[num];
			TR0 = 1;
			while(0xf0 != output);		//检测按键松开
			TR0 = 0;
			SPEAK = 1;	
		}		
	}
	return 0;
}