Classic function signal generator

It can generate triangle wave, square wave and sine wave. It can also adjust the frequency and amplitude.

It is a classic circuit that must be used when learning electronic technology.


/************************************************************************************
* Frequency meter program

* The single chip microcomputer uses AT89S52, and the crystal frequency is: 12.00MHz.
/******************************************************************************/
#include

unsigned char code SEG_Tab[]={0xC0,0xF9,0xA4,0xB0,0x99,0x92,0x82,0xF8,
                          0x80,0x90,0x88,0x83,0xC6,0xA1,0x86,0x8E};//digital code segment
unsigned char code DS_Tab[]={0x01,0x02,0x04,0x08};//bit selection code

unsigned char display_buf[]={0,0,0,0};//value to be displayed

unsigned char digit;

sfr SEG_OUT = 0x80;
sfr DS_OUT = 0xa0;

unsigned char temp[4];
unsigned char T0count;
unsigned char timecount;
unsigned long x;
bit flag; //define

void variables main(void)
{
  unsigned char i;
  TMOD=0x15;
  TH0=0;
  TL0=0;
  TH1=(65536-4000)/256;
  TL1=(65536-4000)%256;
  TR1=1;
  TR0=1;
  ET0=1;
  ET1=1;
  EA=1;//open interrupt
  
while(1)
   {
     if(flag==1)
       {
         flag=0;
         x=T0count*65536+TH0*256+TL0;//convert frequency to numerical value
         for(i=0;i<4;i++)
           {
             temp=0;
           }
         i=0;
         while(x/10)//assign the value to that bit
           {
             temp=x%10;
             x=x/10;
             i++;
           }
         temp=x;
         for(i=0;i<4;i++)
           {
             display_buf=temp;
           }
         timecount=0;
         T0count=0;
         TH0=0;
         TL0=0;
         TR0=1;//clear T0 counter
       }
   }
}

void time0(void) interrupt 1 using 1
{ 
  T0count++; 
}

void t1(void) interrupt 3 using 0
{
  TH1=(65536-4000)/256;//generate one second timing
  TL1=(65536-4000)%256;
  timecount++;
  if(timecount==250)
    {
      TR0=0;
      timecount=0;
      flag=1;
    }
  SEG_OUT = SEG_Tab[display_buf[digit]];//data display of P0 port
  DS_OUT = DS_Tab[digit];//bit selection of P2 portif
  (++digit > 3)
    digit = 0;
}