Hello,

I used the below function on a frequency counter project a few years back.

Regards,

Charles Bannister

//**********************************************
//              float measure_read( void ) funtion
//              Assemble three counter results into
//              float varaiable.
//              Variable x passed to this function is the
//              Residual left over in 74LS393.
//              Frequency total = counter2+counter1+TL0+74LS393
//**********************************************

float measure_read( unsigned char x )
{
  union data1 {
  struct {
    unsigned char a;
    unsigned char b;
    unsigned char c;
        unsigned char d;
    } s;
  unsigned long var1;
  };
        union data1 counts;

        // counts
        counts.s.a = 0;
        counts.s.b = counter2;
        counts.s.c = counter1;
        counts.s.d = TL0;
        x = 0;
        // Take external 74LS393 into equation
        return ((counts.var1 * 256) + x);

}