# How to calculate an RMS table values to select filter curves?

Hi,

I am a beginner in Sigma DSP, using the ADAU1701 chip at MINIZ eval board.

In my application, i have an filter with about 31 curves, then i need to select the curves trough the auxiliary ADC (by potentiometer) and a Lockup table.

The first four points are below, but i need to calculate more points... How to calculate more values for my table?

0
1.19209289550781E-07
2.38418579101562E-07
3.57627868652343E-07

See the attached image for block schematic of my app.

Thanks!

Paulo

• The calculation of index values is described in application note AN-951, which is available here:

http://www.analog.com/static/imported-files/application_notes/AN-951.pdf

On page 11 you can find the formula for converting 28.0 index values to 5.23 values stored in RAM.

Just for everybody's reference, I've listed the first 50 index points in the table below.

 Index Value (5.23 format) 0 0 1 1.19209E-07 2 2.38419E-07 3 3.57628E-07 4 4.76837E-07 5 5.96046E-07 6 7.15256E-07 7 8.34465E-07 8 9.53674E-07 9 1.07288E-06 10 1.19209E-06 11 1.31130E-06 12 1.43051E-06 13 1.54972E-06 14 1.66893E-06 15 1.78814E-06 16 1.90735E-06 17 2.02656E-06 18 2.14577E-06 19 2.26498E-06 20 2.38419E-06 21 2.50340E-06 22 2.62260E-06 23 2.74181E-06 24 2.86102E-06 25 2.98023E-06 26 3.09944E-06 27 3.21865E-06 28 3.33786E-06 29 3.45707E-06 30 3.57628E-06 31 3.69549E-06 32 3.81470E-06 33 3.93391E-06 34 4.05312E-06 35 4.17233E-06 36 4.29153E-06 37 4.41074E-06 38 4.52995E-06 39 4.64916E-06 40 4.76837E-06 41 4.88758E-06 42 5.00679E-06 43 5.12600E-06 44 5.24521E-06 45 5.36442E-06 46 5.48363E-06 47 5.60284E-06 48 5.72205E-06 49 5.84126E-06 50 5.96046E-06
• Thanks BrettG!

Now the filter are operating as I expect.

On my project I will use three potentiometer controlled filters (one LPF, one HPF and one Peak Filter)

Thanks for your assistance.

Paulo