Waveform generator made by 51 single chip microcomputer

I believe that many of you may have come into contact with the production of a wave generator. Maybe you are just getting started, and the things you make are not very complicated. Maybe it is just a rectangular wave or a triangular wave. However, many online materials are misleading. In this regard, I also provide a relatively complete wave generator C51 original:

The software of this system is quite typical: including keyboard application, display application and DA converter application. In this design, there are three kinds of output waveforms: sine wave, square wave and triangle wave.

The output of square wave is the simplest, just change the output voltage according to the set period value.

The output of the triangle wave is also relatively simple. The output of the microcontroller only needs to complete the alternating increase and decrease of the digital quantity.

The output of sine wave is the most troublesome. If the voltage value of each output point is calculated in the software, a lot of CPU time will be wasted, so that the frequency requirement cannot be met. Usually the simplest method is to calculate the voltage value of each output point manually, and then give it in array form when writing the program. When needed, just output it in sequence. This method is faster than the operation method and the shape of the curve can be modified flexibly. In this design, 360 degrees is divided into 256 points, and the interval between each two points is 1.4 degrees, and then the digital value corresponding to the voltage of each point is calculated. As long as this set of data is repeatedly output to DAC0832, the desired sine wave can be obtained at the output end of the system.

The specific procedures are as follows:

#include 
#define uchar unsigned char
#define uint unsigned int
#define DAdata P0
uchar code Sinetab[256]=
{
0x80,0x82,0x84,0x86,0x88,0x8a,0x8c,0x8e,
0x90,0x92,0x94,0x96,0x98,0x9a,0x9c,0x9e,
0xa0,0xa2,0xa4,0xa6,0xa8,0xaa,0xab,0xad,
0xaf,0xb1,0xb2,0xb4,0xb6,0xb7,0xb9,0xba,
0xbc,0xbd,0xbf,0xc0,0xc1,0xc3,0xc4,0xc5,
0xc6,0xc8,0xc9,0xca,0xcb,0xcc,0xcd,0xce,
0xce,0xcf,0xd0,0xd1,0xd1,0xd2,0xd2,0xd3,
0xd3,0xd3,0xd2,0xd2,0xd1,0xd1,0xd0,0xcf,
0xce,0xce,0xcd,0xcc,0xcb,0xca,0xc9,0xc8,
0xc6,0xc5,0xc4,0xc3,0xc1,0xc0,0xbf,0xbd,
0xbc,0xba,0xb9,0xb7,0xb6,0xb4,0xb2,0xb1,
0xaf,0xad,0xab,0xaa,0xa8,0xa6,0xa4,0xa2,
0xa0,0x9e,0x9c,0x9a,0x98,0x96,0x94,0x92,
0x90,0x8e,0x8c,0x8a,0x88,0x86,0x84,0x82,
0x80,0x7d,0x7b,0x79,0x77,0x75,0x73,0x71,
0x6f,0x6d,0x6b,0x69,0x67,0x65,0x63,0x61,
0x5f,0x5d,0x5b,0x59,0x57,0x55,0x54,0x52,
0x50,0x4e,0x4d,0x4b,0x49,0x48,0x46,0x45,
0x43,0x42,0x40,0x3f,0x3e,0x3c,0x3b,0x3a,
0x39,0x37,0x36,0x35,0x34,0x33,0x32,0x31,
0x31,0x30,0x2f,0x2e,0x2e,0x2d,0x2d,0x2c,
0x2c,0x2b,0x2b,0x2b,0x2b,0x2a,0x2a,0x2a,
0x2a,0x2a,0x2a,0x2a,0x2b,0x2b,0x2b,0x2b,
0x2c,0x2c,0x2d,0x2d,0x2e,0x2e,0x2f,0x30,
0x31,0x31,0x32,0x33,0x34,0x35,0x36,0x37,
0x39,0x3a,0x3b,0x3c,0x3e,0x3f,0x40,0x42,
0x43,0x45,0x46,0x48,0x49,0x4b,0x4d,0x4e,
0x50,0x52,0x54,0x55,0x57,0x59,0x5b,0x5d,
0x5f,0x61,0x63,0x65,0x67,0x69,0x6b,0x6d,
0x6f,0x71,0x73,0x75,0x77,0x79,0x7b,0x7d,
};

uchar code Triangletab[58]=
{
0x1a,0x21,0x28,0x2f,0x36,0x3d,0x44,0x4b,
0x52,0x59,0x60,0x67,0x6e,0x75,0x7c,0x83,
0x8a,0x91,0x98,0x9f,0xa6,0xad,0xb4,0xbb,
0xc2,0xc9,0xd0,0xd7,0xde,0xe5,
0xde,0xd7,0xd0,0xc9,0xc2,0xbb,0xb4,0xad,
0xa6,0x9f,0x98,0x91,0x8a,0x83,0x7c,0x75,
0x6e,0x67,0x60,0x59,0x52,0x4b,0x44,0x3d,
0x36,0x2f,0x28,0x21,
};

uchar code Squaretab[2]={0x56,0xaa};

uchar code disp1[]=
{
"Sine Wave"
"Triangle Wale"
"Square Wave"
};

uchar idata disp2[16]={"Frequency: Hz"};

uchar code Coef[3]={10,100,200};

uchar idata WaveFre[3]={1,1,1};

uchar code WaveTH[]=
{
0xfc,0xfe,0xfe,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
0xfc,0xfe,0xfe,0xff,0xff,0xff,0xff,0xff,0xff,0xff,
0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,

};

uchar code WaveTL[]=
{
0xf2,0x78,0xfb,0x3c,0x63,0x7d,0x8f,0x9d,0xa8,0xb1,
0x17,0x0b,0xb2,0x05,0x37,0x58,0x70,0x82,0x90,0x9b,
0x4d,0xa7,0xc4,0xd3,0xdc,0xe2,0xe6,0xea,0xec,0xee
};

uchar Wavecount,THtemp,TLtemp;
uchar Waveform;
sbit rs=P2^5;
sbit rw=P2^6;
sbit e=P2^7;
sbit DA=P2^0;
sbit KEY=P3^2;
void delay(uchar i)
{
uchar j;
for(;i>0;i--)
   for(j=20;j>0;j--);
}

void busy()
{
uchar temp;
temp=0x00;
rs=0;
rw=1;
while((temp&0x80)==0x80)
   {
    P0=0xff;
    e=1;
    temp=P0;
    e=0;
   }
}

void WR_Com(uchar temp)
{
busy();
rs=0;
rw=0;
P0=temp;
e=1;
e=0;
}

void WR_Data(uchar num)
{
busy();
rs=1;
rw=0;
P0=num;
e=1;
e=0;
}

void disp_lcd(uchar addr,uchar *temp1)
{
uchar i;
WR_Com(addr);
delay(100);
for(i=0;i<16;i++)
   {
    WR_Data(temp1[i]);
    delay(100);
   }
}

void lcd_ini()
{
char i;
for(i=3;i>0;i--)
   {
    P0=0x30;
    rs=0;
    rw=0;
    e=1;
    e=0;
    delay(100);
   }
P0=0x38;
rs=0;
rw=0;
e=1;
e=0;
delay(100);
}

void lcd_Reset()
{
WR_Com(0x01);
delay(100);
WR_Com(0x06);
delay(100);
WR_Com(0x0c);
delay(100);
}

void SineOUT(uchar Wavecount)
{
DAdata=Sinetab[Wavecount++];
Wavecount=0;
DA=0;
DA=1;
}

void TriangleOUT(uchar Wavecount)
{
DAdata=Triangletab[Wavecount++];
if(Wavecount>57)
   Wavecount=0;
DA=0;
DA=1;
}

void SquareOUT(uchar Wavecount)
{
DAdata=Squaretab[Wavecount++];
if(Wavecount>1)
Wavecount=0;
DA=0;
DA=1;
}

void timer() interrupt 1
{
TH0=THtemp;
TL0=THtemp;
if(Waveform==0)
   SineOUT(Wavecount);
else if(Waveform==1)
   TriangleOUT(Wavecount);
else if(Waveform==2)
   SquareOUT(Wavecount);
}

void key_int() interrupt 0
{
uchar keytemp,keytemp1;
uint WaveCoef;
EA=0;
TR0=0;
keytemp1=0;
delay(10);
while(!KEY);
keytemp=~P2&0x1e;
keytemp>>=1;
while(keytemp!=8)
   {
    keytemp=~P2&0x1e;
    keytemp>>=1;
    if(keytemp!=keytemp1)
     {
      keytemp1=keytemp;
      switch(keytemp)
       {
        case 1:
         if(++Waveform==3)
          Waveform=0;
         break;
        case 2:
         if(++WaveFre[Waveform]==11)
          WaveFre[Waveform]=1;
         break;
        case 4:
         if (--WaveFre[Waveform]==0)
          WaveFre[Waveform]=10;
         break;
       }
    THtemp=WaveTH[Waveform*16+(WaveFre[Waveform]-1)];
    TLtemp=WaveTL[Waveform*16+(WaveFre[Waveform]-1)];
    WaveCoef=WaveFre[Waveform]*Coef[Waveform];
    disp2[13]=WaveCoef%10+0x30;
    WaveCoef/=10;
    disp2[12]=WaveCoef%10+0x30;
    WaveCoef/=10;
    disp2[11]=WaveCoef%10+0x30;
    WaveCoef/=10;
    disp2[10]=WaveCoef%10+0x30;
    WaveCoef/=10;
    disp_lcd(0x80,&disp1[Waveform*16]);
    disp_lcd(0xc0,disp2);
     }
   }
   TH0=THtemp;
   TL0=THtemp;
   Wavecount=0;
   TR0=1;
}

void main()
{
uint WaveCoef;
uchar i;
lcd_ini();
lcd_Reset();
WaveCoef=WaveFre[Waveform]*Coef[Waveform];
disp2[13]=WaveCoef%10+0x30;
WaveCoef/=10;
disp2[12]=WaveCoef%10+0x30;
WaveCoef/=10;
disp2[11]=WaveCoef%10+0x30;
WaveCoef/=10;
disp2[10]=WaveCoef%10+0x30;
WaveCoef/=10;
disp_lcd(0x80,&disp1[Waveform*16]);
disp_lcd(0xc0,disp2);
i=0;
DAdata=0x00;
DA=0;
TMOD=0x01;
IT0=1;
ET0=1;
EX0=1;
EA=1;
while(1);
}