该系统的软件比较典型：包括键盘的应用，显示的应用和 DA 转换器的应用。本设计中，输出的波形有三种：正弦波，方波，三角波。

方波的输出最为简单，只要按照设定的周期值将输出的电压改变即可。

三角波的输出也比较简单，单片机的输出只要完成数字量递增和递减交替进行即可。、

正弦波的输出最麻烦，如果在软件中计算出输出的各点电压值，将会浪费很多的 CPU 时间，以至于无法满足频率的要求。通常最简单的方法是通过手动的方法计算出输出各点的电压值，然后在编写程序时以数组的方式给出。当需要时，只要按照顺序进行输出即可。这种方法比运算法速度快且曲线的形状修改灵活。在本设计中将 360 度分为 256 个点，则每两个点之间的间隔为 1.4 度，然后计算出每个点电压对应的数字量即可。只要反复输出这组数据到 DAC0832, 就可以在系统输出端得到想要的正弦波。

具体程序如下：

#include reg52.h>

#define uchar unsigned char

#define uint unsigned int

#define DAdata P0uchar code Sinetab[256]=

{0x80,0x82,0x84,0x86,0x88,0x8a,0x8c,0x8e,0x90,0x92,

0x94,0x96,0x98,0x9a,0x9c,0x9e,0,0xa2,0xa4,0xa6,0xa8,

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,0xa8,0xa6,0xa4,0xa2,0,0x9e,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((temp0x80)==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;i16;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=~P20x1e;keytemp>>=1;while(keytemp!=8){keytemp=~P20x1e;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);}