Design of a simple electronic piano system based on a single chip microcomputer (program)

#include  

#define uint unsigned int 

#define uchar unsigned char

#define output P1

#define input P1

//Easy to transplant to other circuit boards, my circuit uses P1 port as keyboard input interface

//Define 16 buttons

enum KEY{key0,key1,key2,key3,key4,key5,key6,key7,key8,key9,key10,key11,key12,key13,key14,key15};

uchar code table[]={   //array definition, display digital tube

    0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,

    0x7f,0x6f,0x77,0x7c,0x39,0x5e,0x79,0x71,0x00};

unsigned int code Freqtab[] = { //initial value of timing half cycle

     64021,64103,64260,64400, //Bass 3 4 5 6

     64524,64580,64684,64777, //Bass 7, Midrange 1 2 3

     64820,64898,64968,65030, // Middle 4 5 6 7

     65058,65110,65157,65178}; //treble 1 2 3 4

uint FreqTemp;

//The buzzer sound is not very good, so we use a speaker, connected to P3.7 port

sbit SPEAK = P3^7;

void delay1ms(uint n) //error 0us, delay n milliseconds

{

    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; //temporarily save the read row or column

uchar num = 16; //Return the value of the key    

output = 0x0f;

    temp1 = input; //Read the line first

if(0x0f != temp1)    //button pressed

{    

delay1ms(5); //delay to eliminate jitter

temp1 = input; // read line again

if(0x0f != temp1) //Indicates that the button is pressed

{

temp1 = temp1 & 0x0f; //Retain the lower 4 bits

output = 0xf0; //Ready to read the column

delay1ms(1); //Delay to prevent the next sentence from being missed

temp2 = input; //Read the column directly

temp2 = temp2 & 0xf0; //Reserve the upper 4 bits

temp1 = temp1 | temp2; //Merge the values ​​of temp1 and temp2

}

}

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; //Load the initial value of the timing half cycle

     TH0 = FreqTemp >> 8;

     SPEAK = ~SPEAK; //pronunciation

} 

int main()

{

TMOD = 0X01; //Timer T0 is set to mode 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); //Detect button release

TR0 = 0;

SPEAK = 1;

}

}

return 0;

}