Voltage and Current RMS scale factor in energy library

I was doing this for my own project using the F67791 EVM. Here is what I have found out about Voltage Scaling Factors....

int32_t voltage(struct phase_parms_s *phase, struct phase_nv_parms_s const *phase_nv)

    {

        int16_t i;

        int32_t x;

    

        /* Calculate the RMS voltage in 10mV increments. Return -1 for overrange

           (i.e. ADC clip). */

        if ((phase->status & V_OVERRANGE))

           return -1;

        x = div_sh48(phase->metrology.dot_prod_logged.V_sq, 26 - 2*ADC_BITS, phase->metrology.dot_prod_logged.sample_count);

        //ADC_BITS for our application is 16.

        /*

        Now this function div_sh48 takes three arguments. First is V_sq. It is 48 bit number stored in an 3 member 

        array of 16 bit each. As I was debugging I found that it's value was 10238, 19060,238. Now the binary representation

        of these numbers is 

        0010011111111110  //10238

        0100101001110100  //19060

        0000000011101110  //238

        Now we need to make the 48 bit number out of these. The most significant 16 bits are 238.

        So the final number will be

        000000001110111001001010011101000010011111111110

        In Decimal it is 1023451342846

        Now I have found that the function div_sh48(48bit number, Shift No of bits, Divide) will first shift and then divide.

        So I shifted the number by -6 (i.e Shift Right) -6 is basically 26-2*16 = -6

        Shift Right by 6 and the answer is 15991427231

        Now the sample_count for this particular samplpe was 4137

        So Divide 15991427231 by 4137 the answer is 3865464.

        Square Root of this number is Square Root    1966.0783

        Now the isqrt32 function returns the number as 0xZZZZYYYY where ZZZZ is hex of 1966 and YYYY is hex of 0783

        So the answer would be 07AE030F.

        Now x>>12 will truncate the last three and we will get 0x7AE0 i.e 31456 in decimal.

        Now we multiply this with the scaling factor i.e 12300

        31456 x 12344 = 388292864

        Now when we shift right by 14 this number we get 

        Shift Right By 14 = 23699 which is 236.99V

        

        Next step is to find the relationship between scaling factor and Vrequired and Vobserved. 

        So I tested using different scaling factors and the result is 

        If scaling factor is 10,000 then Vrms=191.99v

        If scaling factor is 11,000 then Vrms=211.19v

        If scaling factor is 12,000 then Vrms=230.39v

        If scaling factor is 13,000 then Vrms=249.58v

        So I noted that Vrms/scaling_factor is a constant.

        So I concluded that the formula for scaling factor can be deducted by 

        If Voltage calculated by meter is 236.99 then scaling factor is 12300

        If voltage is 1 then scaling factor = 12300/236.99

        If voltage is Vreq then scaling factor is 123000 * Vreq/VObs

        As an example lets say I have supplied 230V to the meter but it is showing 236.99V and the scaling factor is 12300 then

        New_scaling_factor = old_scaling_factor * Vreq/VObs

        i.e 12300 * 230/236.99 = 11937.

        Now to confirm this we put this scaling factor in the calculation 

        x = (x >> 12)*i;

        x >>= 14;

        return x;

        x is 31456 and now i is 11937

        31456 * 11937 = 375490272

        Now >>14 of this number is 22918

        */

        

        i = phase_nv->V_rms_scale_factor;

        x = isqrt32(x);

        x = (x >> 12)*i;

        x >>= 14;

        return x;

        /*----------------------------------------------*/

        // This is where scaling of voltage is done. It reads

        //the current voltage 

        /*----------------------------------------------*/

    }