产生波形实验（DA转换）

/*DA转换实验 例如产生锯齿波*/ 



 #include <reg52.h> 



 unsigned char xdata ad_cs0   _at_  0xc000; 

 unsigned char xdata ad_cs1   _at_  0xc001 ; 

 unsigned char xdata key_seg   _at_  0xd004; 

 unsigned char xdata key_bit   _at_  0xd002; 



 sbit EOC=P3^2; 

 unsigned char disp_ram[6]; 

 unsigned char seg7[]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f, 

                       0x77,0x7c,0x39,0x5e,0x79,0x71,0,0x80}; 

 unsigned char scan[]={0x01,0x02,0x04,0x08,0x10,0x20}; 



 void delay() 

 { 

   unsigned char i,j; 

   for (i=0;i<200;i++) 

     for (j=0;j<2;j++); 

 } 



 void main() 

 { 

    unsigned char i=0; 

    unsigned char ad_value; 

    unsigned char tmp,a; 







     disp_ram[0]=17; 

     disp_ram[1]=16; 

     disp_ram[2]=16; 

     disp_ram[3]=16; 

     disp_ram[4]=16; 

     disp_ram[5]=16; 



     ad_cs0=0; 



     while(1) 

     { 

        key_bit=scan[i]; 

        a=seg7[disp_ram[i]]; 

        if (i==5) 

           a=a|0x80; 

        key_seg=a; 

        delay(); 

        i++; 

        i=i%6  ; 



        if (EOC) 

        { 

           ad_value=ad_cs0; 

           disp_ram[5]=ad_value*5/256; 

           tmp=(ad_value*5)%256; 

           disp_ram[4]=tmp/100; 

           disp_ram[3]=(tmp%100)/10; 

        } 

        ad_cs0=0; 

     } ; 





 }

DA转换 Code