Design of music box based on 51 single chip microcomputer

1. Hardware Solution

This design uses the 51 single-chip microcomputer principle and control theory to design the hardware circuit of the music performance controller, and uses C language for program design. By controlling the timer inside the single-chip microcomputer to generate square waves of different frequencies, the buzzer is driven to emit music of different tones, and the delay is used to control the length of the pronunciation time. By converting the music score into the corresponding timing constant, you can play pleasant music from the pronunciation device.

It is mainly composed of 51 single chip microcomputer + minimum system + LM386 power amplifier circuit + speaker + LED indicator module + button module; as shown in the figure:

2. Design function

(1) Using an external power amplifier circuit and LM386 chip to drive the speaker, the hardware circuit of the music player is formed;

(2) Built-in 8 songs;

(3) Four button functions: a single button for reset, previous song, start/pause, and next song;

3. Design Schematic

(1) The schematic diagram is mainly designed using AD software, as shown in the figure:

(2) The Protues simulation diagram is as follows:

(3) The PCB diagram is as follows:

4. Software Design

(1) Program flow chart

(2) Main program source code

void main(void)

{

TMOD=0x11; //T0 T1 are both in working mode 1

ET0=1; //T0 opens interrupt

EA=1; //CPU interrupt  

while(1)

{

music_play(); //Play a note of the corresponding song according to the current state

if(!pause) //Pause key processing

{

delayms(5);

if(!pause)

{

if(music_num==0) //music_num=0 only exists when the device is just powered on and the pause button is not pressed, indicating the state when the device is just powered on. Press the button to start playing from the first song.

{

music_num=1; //Set the song number to 1

num=0;         //play from the beginning

play_enable=1; //Allow playback

}

else

{

play_enable=~play_enable;

    speaker=1;

}

while(!pause) //What to do if you hold down the pause button

{

if(play_enable==0){}         //If it is paused, the display time remains unchanged //(play_enable==0 when paused)

}

  }//Pause key processing ends

}//while ends

if((!play_up)&&(music_num!=0)) //Previous song button

{

delayms(5);

if((!play_up)&&(music_num!=0))

{ speaker=1;

music_num-=1; // song number minus one

if(music_num<=0)

music_num=8;

num=0; //Start playing from the beginning

if(music_num==(sound_amount+1))

music_num=1; 

delayms(500); // song switching delay 0.5S

}

}

if((!play_down)&&(music_num!=0))

{

delayms(5);

if((!play_down)&&(music_num!=0))

{ speaker=1;

music_num+=1; //Song number plus one

if(music_num>=9)

music_num=1;

num=0; //Start playing from the beginning

if(music_num==0)

music_num=sound_amount;

delayms(500); // song switching delay 0.5S

}

}

}

}