这是我做的信号发生器课设，用proteus画的原理图，keil4.1编写的C语言。
仿真原理图如下

单片机源程序如下：

#include

#define uchar unsigned char

#define uint  unsigned int

#define DAdata P0 //DA数据端口

sbit DA_S1=P2^0;

sbit DA_S2=P2^1;

sbit key =P3^2;

uchar wavecount; //波形波码计数标志

uchar THtemp,TLtemp;//传递频率的中间变量

uchar judge=1;   //用于方波函数，作标志

uchar waveform;  //波形计数标志，值不同代表不同的波形

uchar code         freq_unit[3]={10,50,200};//3种波形的频率单位

uchar idata wavefreq[3]={1,1,1}; //数组单元，用于存放单位频率的个数

uchar code  lcd_hang1[]={"SineWave  ""TriangleWave  ""SquareWave " "sawtoothWave "   "Select Wave   "   "  Press No.1 key!    "};

uchar idata lcd_hang2[16]={"f=    Hz      "};

uchar code waveTH[]={0xfe,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,

                                           0xf9,0xfc,0xfd,0xfe,0xfe,0xfe,0xff,0xff,0xff,0xff,

                                         0xf6,0xfb,0xfd,0xfb,0xfe,0xff,0xff,0xff,0xff,0xff};

/**********************************/

uchar code waveTL[]={

0x79,0x3d,0x7e,0x9e,0xbe,0xbf,0xc8,0xcf,0xd4,0xd9,//正弦波频率调整中间值

0xe8,0xf4,0xf8,0x7a,0x7c,0xfc,0x23,0x3d,0x53,0x64,//锯齿波频率调整中间值

0x3c,0x1e,0x8f,0x32,0xc7,0x63,0xb1,0xd8,0xec,0xf6};//方波频率调整中间值

/*********************************/

uchar code sawtooth_tab[]={

0x00,0x04,0x08,0x0c,0x10,0x14,0x18,0x1c,0x20,0x24,0x28,0x2c,

0x30,0x34,0x38,0x3c,0x40,0x44,0x48,0x4c,0x50,0x54,0x58,0x5c,

0x60,0x64,0x68,0x6c,0x70,0x74,0x78,0x7c,0x80,0x84,0x88,0x8c,

0x90,0x94,0x98,0x9c,0,0xa4,0xa8,0xac,0xb0,0xb4,0xb8,0xbc,

0xc0,0xc4,0xc8,0xcc,0xd0,0xd4,0xd8,0xdc,0xe0,0xe4,0xe8,0xec,

0xf0,0xf4,0xf8,0xfc};

/*****************************/

uchar code sine_tab[256]={

0x80,0x83,0x86,0x89,0x90,0x93,0x96,0x99,0x9c,0x9f,

0xa2,0xa5,0xa8,0xab,0xae,0xb1,0xb4,0xb7,0xba,0xbc,0xbf,

0xc2,0xc5,0xc7,0xca,0xcc,0xcf,0xd1,0xd4,0xd8,0xda,0xdd,0xdf,

0xe1,0xe3,0xe5,0xe7,0xe9,0xea,0xec,0xee,0xef,0xf1,0xf2,0xf4,

0xf5,0xf6,0xf7,0xf8,0xf9,0xfa,0xfb,0xfc,0xfd,0xfd,0xfe,0xff,

0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xfe,

0xfd,0xfd,0xfc,0xfb,0xfa,0xf9,0xf8,0xf7,0xf6,0xf5,0xf4,0xf2,0xf1,

0xef,0xee,0xec,0xea,0xe9,0xe7,0xe5,0xe3,0xe1,0xde,0xdd,0xda,0xd8,

0xd6,0xd4,0xd1,0xcf,0xcc,0xca,0xc7,0xc5,0xc2,0xbf,0xbc,0xba,0xb7,

0xb4,0xb1,0xae,0xab,0xa8,0xa5,0xa2,0x9f,0x9c,0x99,0x96,0x93,0x90,

0x8d,0x89,0x86,0x83,0x80,0x7c,0x79,0x76,0x72,0x6f,0x6c,0x69,0x66,

0x63,0x60,0x5d,0x5a,0x57,0x55,0x51,0x4e,0x4c,0x48,0x45,0x43,0x40,

0x3d,0x3a,0x38,0x35,0x33,0x30,0x2e,0x2b,0x29,0x27,0x25,0x22,0x20,

0x1e,0x1c,0x1a,0x18,0x16,0x15,0x13,0x11,0x10,0x0e,0x0d,0x0b,0x0a,

0x09,0x08,0x07,0x06,0x05,0x04,0x03,0x02,0x02,0x01,0x00,0x00,0x00,

0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x01,0x02,0x02,0x03,

0x04,0x05,0x06,0x07,0x08,0x09,0x0a,0x0b,0x0d,0x0e,0x10,0x11,0x13,

0x15,0x16,0x18,0x1a,0x1c,0x1e,0x20,0x22,0x25,0x27,0x29,0x2b,0x2e,

0x30,0x33,0x35,0x38,0x3a,0x3d,0x40,0x43,0x45,0x48,0x4c,0x4e,0x51,

0x55,0x57,0x5a,0x5d,0x60,0x63,0x66,0x69,0x6c,0x6f,0x72,0x76,0x79,0x7c,0x80};

/**************************************************/

void delay(uchar z)

{

     uchar x,y;

         for(x=z;x>0;x--)

          for(y=110;y>0;y--);

}

/*

void sawtooth_out()//锯齿波输出

{         

         uchar i;

     for(i=255;i>0;i--)

         {

                    DAdata=i; 

                 DA_S1=0;//打开8位输入寄存器

             DA_S1=1;//关闭8位输入寄存器  

         }

}

*/

void sawtooth_out()//锯齿波输出

{

            DAdata=sawtooth_tab[wavecount++];

         if(wavecount>64) wavecount=0;

             DA_S1=0;//打开8位输入寄存器

             DA_S1=1;

}

void sine_out()//正弦波输出

{

     DAdata=sine_tab[wavecount++];

         DA_S1=0;//打开8位输入寄存器

         DA_S1=1;//关闭8位输入寄存器

}

void square_out()//方波输出

{

         judge=~judge;

         if(judge==1)

            DAdata=0xff;

         else 

            DAdata=0x00;

                DA_S1=0;//打开8位输入寄存器

            DA_S1=1;//关闭8位输入寄存器

}

/******************************/

/**********1602***************/

/****************************/

#define lcd_ports  P1

sbit rs=P2^2;

sbit rw=P2^3;

sbit lcden=P2^4;

void write_com(uchar com)

{

         rs=0; //写指令

         lcden=0;

         lcd_ports=com;

         delay(5);

         lcden=1;

         delay(5);

     lcden=0;

}

void write_date(uchar date)

{

         rs=1; //写数据

         lcden=0;

         lcd_ports=date;

         delay(10);

     lcden=1;

         delay(10);

     lcden=0;

}

void disp_lcd(uchar addr,uchar *temp1) 

{

         uchar num;

         write_com(addr);

         delay(1);

         for(num=0;num<16;num++)

         {

             write_date(temp1[num]);

                 delay(10);

         }

}

void init_lcd()

{

     lcden=0;

         rw=0;        //初始化一定要设置为零，表示写数据

         write_com(0x38);//使液晶显示点阵，为下面做准备

         write_com(0x0c);//初始设置

         write_com(0x06);//初始设置

         write_com(0x01);//清零

         write_com(0x80);//使指针指向第一行第一格

         disp_lcd(0x80,&lcd_hang1[3*16]);//在第一行显示

         disp_lcd(0xc0,&lcd_hang2[4*16]);//在第二行显示

}

/**********************************************/

void main()

{

           DA_S2=0;

     DAdata=0;

         DA_S1=1; //关闭8位输入寄存器

         init_lcd();

         waveform=0;

         TMOD=0x01;//设定定时器0为16位工作方式

         IT0=1;//设置外部中断0为下降沿触发

         ET0=1;//开定时器中断

         EA=1;

         while(1)

         {

         }

}

void key_int0() interrupt 0

{

     uchar keytemp;

         uint  total_freq;//总频率

         EA=0;

         TR0=0;

         delay(10);        

         if(key==0)           //判断按键是否按下

         {

            keytemp=P3&0xf0;//获取P3口高四位的值

                switch(keytemp) //根据按键次数选择波形

                {          

                    case 0xe0:

                                  waveform++;

                              if(waveform>2)waveform=0;  

                                          break;

                        case 0xd0:

                                        wavefreq[waveform]++; //        频率按单位增加

                              if(wavefreq[waveform]>10)wavefreq[waveform]=1; 

                                          break;

case 0xb0: // 频率按单位递减