基于MCS51设计的概念版的信号发生器

系统简介：这款信号发生器的原理是利用单片机控制DAC0832数模转化芯片，使其输出-5~+5的模拟量信号，由于单片机的指令执行周期很短，其中Atmel89s52最大可支持24M的晶振，可以用数字信号产生很好的“模拟”信号。

这款系统只是概念上的，因为受到数模芯片转化时间和单片机程序控制时间的限制，只能在很小的频率范围内出比较好的波形，这款系统主要还是其程序的控制，其中控制程序占有整个程序的90%左右。

一块4×4的矩阵键盘向单片机提供输入，使LCD1602液晶显示出频率和幅值，通过抄作键盘可以改变相应的频率、幅值以及输出波形。

 

 

系统构成部件：

单片机Atmel89s52、数模转换芯片DAC0832、4×4键盘、LCD1602液晶显示

 

 

模块介绍：

4×4的矩阵键盘

 

 

数模转换：DAC0832，基本接法

 

 

显示：LCD1602

 

 

波形输出：DAC0832的双极型输出

 仿真波形：

 LCD显示：

程序设计： 

#include    //包含单片机寄存器的头文件

#include  //包含_nop_()函数定义的头文件

#define uchar unsigned char

#define uint unsigned int

sbit RS=P3^0;    //寄存器选择位，将RS位定义为P2.0引脚

sbit RW=P3^1;    //读写选择位，将RW位定义为P2.1引脚

sbit E=P3^2;     //使能信号位，将E位定义为P2.2引脚

sbit BF=P0^7;    //忙碌标志位，，将BF位定义为P0.7引脚

sbit CS=P3^7; //DA0832片选信号

bit F_Flag=0;

bit SET_Flag=0;

bit Wave_Flag=1;

unsigned char Flag=0;

unsigned char j=0;

unsigned char a=0;

unsigned int F_Val=100;

unsigned int A_Val=5000;

unsigned int u1,u2;

unsigned char code digit[ ]={"0123456789"}; //定义字符数组显示数字

unsigned char code string[ ]= {" F: 100HZ "};

unsigned char code string1[ ]={"      A:5000mV "};

unsigned char code string2[ ]={"SIN"};

unsigned char code string3[ ]={"TRA"};

unsigned char code string4[ ]={"REC"};

unsigned char code key_code[]={

              0xee,0xde,0xbe,0x7e,0xed,0xdd,0xbd,0x7d,

              0xeb,0xdb,0xbb,0x7b,0xe7,0xd7,0xb7,0x77 };

uchar code tosin[256]={

0x80,0x83,0x86,0x89,0x8d,0x90,0x93,0x96,0x99,0x9c,0x9f,0xa2,

0xa5,0xa8,0xab,0xae,0xb1,0xb4,0xb7,0xba,0xbc,0xbf,0xc2,0xc5,

0xc7,0xca,0xcc,0xcf,0xd1,0xd4,0xd6,0xd8,0xda,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,0x89,0x86,0x83,0x80,0x80,0x7c,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};//正弦波码

 

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

函数功能：延时1ms

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

void delay1ms()

{

   unsigned char i,j;    

        for(i=0;i<10;i++)

         for(j=0;j<33;j++)

          ;       

 }

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

函数功能：延时若干毫秒

入口参数：n

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

 void delay(unsigned int n)

 {

   unsigned int i;

       for(i=0;i

          delay1ms();

 }

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

函数功能：判断液晶模块的忙碌状态

返回值：result。result=1，忙碌;result=0，不忙

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

 unsigned char BusyTest(void)

  {

    bit result;

       RS=0;       //根据规定，RS为低电平，RW为高电平时，可以读状态

    RW=1;

    E=1;        //E=1，才允许读写

    _nop_();   //空操作

    _nop_();

    _nop_();

    _nop_();   //空操作四个机器周期，给硬件反应时间    

    result=BF;  //将忙碌标志电平赋给result

       E=0;

    return result;

  }

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

函数功能：将模式设置指令或显示地址写入液晶模块

入口参数：dictate

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

void WriteInstruction (unsigned char dictate)

{  

    while(BusyTest()==1); //如果忙就等待

        RS=0;                  //根据规定，RS和R/W同时为低电平时，可以写入指令

        RW=0;  

        E=0;                   //E置低电平(根据表8-6，写指令时，E为高脉冲，

                             // 就是让E从0到1发生正跳变，所以应先置"0"

        _nop_();

        _nop_();             //空操作两个机器周期，给硬件反应时间

        P0=dictate;            //将数据送入P0口，即写入指令或地址

        _nop_();

        _nop_();

        _nop_();

        _nop_();               //空操作四个机器周期，给硬件反应时间

        E=1;                   //E置高电平

        _nop_();

        _nop_();

        _nop_();

        _nop_();               //空操作四个机器周期，给硬件反应时间

         E=0;                  //当E由高电平跳变成低电平时，液晶模块开始执行命令

 }

 

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

函数功能：指定字符显示的实际地址

入口参数：x

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

 void WriteAddress(unsigned char x)

 {

     WriteInstruction(x|0x80); //显示位置的确定方法规定为"80H+地址码x"

 }

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

函数功能：将数据(字符的标准ASCII码)写入液晶模块

入口参数：y(为字符常量)

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

 void WriteData(unsigned char y)

 {

    while(BusyTest()==1); 

         RS=1;           //RS为高电平，RW为低电平时，可以写入数据

         RW=0;

         E=0;            //E置低电平(根据表8-6，写指令时，E为高脉冲，

                       // 就是让E从0到1发生正跳变，所以应先置"0"

         P0=y;           //将数据送入P0口，即将数据写入液晶模块

         _nop_();

         _nop_();

        _nop_();

     _nop_();       //空操作四个机器周期，给硬件反应时间

         E=1;          //E置高电平

         _nop_();

         _nop_();

         _nop_();

        _nop_();        //空操作四个机器周期，给硬件反应时间

        E=0;            //当E由高电平跳变成低电平时，液晶模块开始执行命令

 }

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

函数功能：对LCD的显示模式进行初始化设置

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

void LcdInitiate(void)

{

   delay(15);             //延时15ms，首次写指令时应给LCD一段较长的反应时间

   WriteInstruction(0x38);  //显示模式设置：16×2显示，5×7点阵，8位数据接口

       delay(5);   //延时5ms　

       WriteInstruction(0x38);

       delay(5);

       WriteInstruction(0x38);

       delay(5);

       WriteInstruction(0x0F);  //显示模式设置：显示开，有光标，光标闪烁

       delay(5);

       WriteInstruction(0x06);  //显示模式设置：光标右移，字符不移

       delay(5);

       WriteInstruction(0x01);  //清屏幕指令，将以前的显示内容清除

       delay(5);

 }

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

 

键盘扫描子函数

 

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

uchar  keyscan()

{

   uchar  scan1,scan2,keycode,j,key;

 

   P2=0xf0;

   scan1=P2;

   if((scan1&0xf0)!=0xf0)           //判键是否按下

   {

     delay(10);                   //延时10ms

     scan1=P2;

     if((scan1&0xf0)!=0xf0)         //二次判键是否按下

     {

        P2=0x0f;

        scan2=P2;

        keycode=scan1|scan2;         //组合成键编码

 

        for(j=0;j<=15;j++)

        {

           if(keycode== key_code[j])  //查表得键值

           {

              key=j;

                      

              return(key);

           }

        }

     }

   }

      else  P1=0xff;

 

   return (16);

}

/****************延时中断子程序1*****************/

void timer0() interrupt 1

{    

              if(Flag==0)    //正弦波

              P1=tosin[j];          

      

          if(Flag==1)//三角波

              if(j<128)

                            P1=A_Val*j/5000;

               else

           P1=A_Val*(255-j)/5000;

          if(Flag==2)   //方波

       {if(j<128)       

               P1=A_Val/20;

        else P1=255-A_Val/20;

           a=0;}

       j++;  

 }

 

            

                    

 

void main(void)            //主函数

 {

  unsigned char i;

  LcdInitiate();         //调用LCD初始化函数 

  delay(10);

 

       WriteInstruction(0x01);//清显示：清屏幕指令

               WriteAddress(0x00);  // 设置显示位置为第一行的第1个字

                  i = 0;

              while(string[i] != '\0')    //'\0'是数组结束标志

                     {                                        // 显示字符  

                                   WriteData(string[i]);

                                   i++;

                                   delay(40);

                     }

                    

               WriteAddress(0x40);  // 设置显示位置为第二行的第1个字

                  i = 0;

              while(string[i] != '\0')   //'\0'是数组结束标志

                     {                                        // 显示字符  

                                   WriteData(string1[i]);

                                   i++;

                                   delay(40);

                      }

                     WriteAddress(0x67);

while(1)                             

{    

 

if(keyscan()==10&&SET_Flag==0)

        { delay(20);

         if(keyscan()==10&&SET_Flag==0)

       {   Flag++;

              if(Flag==3)

              Flag=0;

         WriteAddress(0x01);

        _nop_();

         _nop_();

        _nop_();

     _nop_();

     if(Flag==0)

         { i = 0;

              while(string2[i] != '\0')   //'\0'是数组结束标志

                     {                                        // 显示字符   SIN

                                   WriteData(string2[i]);

                                   i++;

                                   delay(40);

                     }

                     }

        if(Flag==1)

         { i = 0;

              while(string3[i] != '\0')   //'\0'是数组结束标志

                     {                                        // 显示字符   TRA

                                   WriteData(string3[i]);

                                   i++;

                                   delay(40);

                     }

                     }

       if(Flag==2)

         { i = 0;

              while(string4[i] != '\0')   //'\0'是数组结束标志

                     {                                        // 显示字符   REC

                                   WriteData(string4[i]);

                                   i++;

                                   delay(40);

                     }

                     }

        delay(400);

              }    

       WriteAddress(0x67);     

              }

 

       if(keyscan()==11)

        { delay(20);

         if(keyscan()==11)

       {  if(F_Flag==0)

        WriteAddress(0x46);

        else

        WriteAddress(0x06);

           delay(500) ;

              F_Flag=!F_Flag;

              SET_Flag=1;

              Wave_Flag=1;                

              }    

        }   

               if(keyscan()==12&&SET_Flag==1)

               { delay(20);

                if(keyscan()==12&&SET_Flag==1)

               {unsigned char D1,D2,D3,D4;

                 unsigned int Val;

                 if(F_Flag==0)

                 {Val=F_Val;

                  WriteAddress(0x08);}

                 else {Val=A_Val;

                  WriteAddress(0x48);}

          Val=Val+10;

                D1=Val%10;              //计算个位数字

                D2=(Val%100)/10;        //计算十位数字

                D3=(Val%1000)/100;      //计算百位数字

                D4=Val/1000;           //计算千位数字  

                WriteData(digit[D4]);  //将千位数字的字符常量写入LCD

                WriteData(digit[D3]);  //将百位数字的字符常量写入LCD

                WriteData(digit[D2]);  //将十位数字的字符常量写入LCD

                WriteData(digit[D1]);  //将个位数字的字符常量写入LCD

                if(F_Flag==0)

                 F_Val=Val;

                 else A_Val=Val;

                }

                 if(F_Flag==0)

       WriteAddress(0x06);

       else  WriteAddress(0x46);

       delay(400);    

       }

             

               if(keyscan()==13&&SET_Flag==1)

               { delay(20);

                if(keyscan()==13&&SET_Flag==1)

               {unsigned char D1,D2,D3,D4;

                 unsigned int Val;

                 if(F_Flag==0)

                 {Val=F_Val;

                   WriteAddress(0x08); }

                 else {Val=A_Val;

                   WriteAddress(0x48);}

          Val=Val-10;

                D1=Val%10;              //计算个位数字

                D2=(Val%100)/10;        //计算十位数字

                D3=(Val%1000)/100;      //计算百位数字

                D4=Val/1000;           //计算千位数字   

                WriteData(digit[D4]);  //将千位数字的字符常量写入LCD

                WriteData(digit[D3]);  //将百位数字的字符常量写入LCD

                WriteData(digit[D2]);  //将十位数字的字符常量写入LCD

                WriteData(digit[D1]);  //将个位数字的字符常量写入LCD

                if(F_Flag==0)

                 F_Val=Val;

                 else A_Val=Val;

                 }

                 if(F_Flag==0)

       WriteAddress(0x06);

       else WriteAddress(0x46);

       delay(400);    

              }

              if(keyscan()==14)

              {delay(20);

              if(keyscan()==14)

              {SET_Flag=0;

           Wave_Flag=1;

           WriteAddress(0x76);

              }

              }

 

       if(Wave_Flag==1)

       {     CS=0;

      u1=3906/F_Val;

       u2=3906%F_Val;

      if(u2>F_Val/2)

        u1++;

              TMOD=0x02;

              TH0=TL0=255-u1;

        EA=1;

              ET0=1;

              TR0=1;  

       }

   if(keyscan()!=16)

   TR0=TR1=0;

 

       }    

   }

  总结：优秀的程序设计源自于优秀的硬件系统，好的硬件电路可以大大提高开发效率，单片机开发应该走接口的模块话和标准化，这样可以大大减少开发人员的工作量，单片机接口模块的开发也较具有市场前景！

       电路的设计不能完全依赖于教科书上所说的，教科书只是一些理论性的东西，而一个优秀稳定的电路系统要求的更多。

           51单片机的速度不够、处理浮点数运算的能力不强，代码效率不高，在ARM系统如火如荼的时候，我们竟然还在学51！