利用单片机AT89S51与ADC0809设计一个数字电压表,能够测量0-5V之间的直流电压值,四位数码显示,但是使用的元器件数目最少。
 
#include 
unsigned char code dispbitcode[]={0xfe,0xfd,0xfb,0xf7, 
                                  0xef,0xdf,0xbf,0x7f}; 
unsigned char code dispcode[]={0x3f,0x06,0x5b,0x4f,0x66, 
                               0x6d,0x7d,0x07,0x7f,0x6f,0x00}; 
unsigned char dispbuf[8]={10,10,10,10,0,0,0,0}; 
unsigned char dispcount; 
unsigned char getdata; 
unsigned int temp; 
unsigned char i; 
sbit ST=P3^0; 
sbit OE=P3^1; 
sbit EOC=P3^2; 
sbit CLK=P3^3; 
void main(void) 
{ 
  ST=0; 
  OE=0; 
  ET0=1; 
  ET1=1; 
  EA=1; 
  TMOD=0x12; 
  TH0=216; 
  TL0=216; 
  TH1=(65536-4000)/256; 
  TL1=(65536-4000)%6; 
  TR1=1; 
  TR0=1; 
  ST=1; 
  ST=0; 
  while(1) 
    { 
      if(EOC==1) 
        { 
          OE=1; 
          getdata=P0; 
          OE=0; 
          temp=getdata*235; 
          temp=temp/128; 
          i=5; 
          dispbuf[0]=10; 
          dispbuf[1]=10; 
          dispbuf[2]=10; 
          dispbuf[3]=10; 
          dispbuf[4]=10; 
          dispbuf[5]=0; 
          dispbuf[6]=0; 
          dispbuf[7]=0; 
          while(temp/10) 
            { 
              dispbuf[i]=temp; 
              temp=temp/10; 
              i++; 
            } 
          dispbuf[i]=temp;          
          ST=1; 
          ST=0; 
        } 
    } 
} 
void t0(void) interrupt 1 using 0 
{ 
  CLK=~CLK; 
} 
void t1(void) interrupt 3 using 0 
{ 
  TH1=(65536-4000)/256; 
  TL1=(65536-4000)%6; 
  P1=dispcode[dispbuf[dispcount]]; 
  P2=dispbitcode[dispcount]; 
  if(dispcount==7) 
    { 
      P1=P1 | 0x80; 
    } 
  dispcount++; 
  if(dispcount==8) 
    { 
      dispcount=0; 
    }  
}