CCS/TAS5825M: We need software source code of the PPC3 EQ module

Hello Duan,

Please refer to this link for matlab code of EQ: https://e2e.ti.com/support/audio/f/6/p/906715/3351799?tisearch=e2e-sitesearch&keymatch=%25252525252520user%2525252525253A320278#3351799.

Further code below is also for your reference. Note that results may not exactly the same with PPC3 due to calculation precision, but it is right.

• Relationship between audio cook book and PPC3.

               b0_PPC3 = b0;           % data format is 1.31

               b1_PPC3 = b1 / 2;      % data format is 2.30, hence need divided by 2

               b2_PPC3 = b2;

               a1_PPC3 = -a1 / 2;     % -1 is software cfg

               a2_PPC3 = -a2;

• Audio cook book and dataformat of EQ coefficients.

Step 1: Get the b0, b1, b2, a0, a1, a2 parameters from the formula in the Audio-EQ-cookbook:https://webaudio.github.io/Audio-EQ-Cookbook/Audio-EQ-Cookbook.txt

Step 2: Normalize the b0, b1, b2, a0, a1, a2 to get the b0_a0, b1_a0, b2_a0, a0_a0, a1_a0, a2_a0, k.

        b0_a0=(b0/a0);                 %1.31 format

        b1_a0=(b1/a0)/2;             %2.30 format

        b2_a0=(b2/a0);              %1.31 format

        k1=max(abs([b0_a0,b1_a0,b2_a0]));        % Divide by the max value to avoid overflow

        if k1>0.99999988079071044921875;

            k=k1/0.99999988079071044921875;

            b0_a0=b0_a0/k;

            b1_a0=b1_a0/k;

            b2_a0=b2_a0/k;

        else

            k=1;

        end

        a0_a0=(a0/a0);

        a1_a0=(a1/a0)/2;               %2.30 format

        a2_a0=(a2/a0);                   %1.31 format

Step 3: Transfer the b0_a0, b1_a0, b2_a0, a1_a0, a2_a0 to 32bit 2's complement

[B0,B1,B2,A1,A2] = dec2hex(mod(min(round(2^(32-1)*[ b0_a0, b1_a0, b2_a0, a1_a0, a2_a0]),2^(32-1)-1),2^32));

Step 4:  Write the [B0,B1,B2,A1,A2] to the right register address, multiply the value ‘k’ back in the step 2 to the volume register or the b0, b1, b2 of 15th BQ.

BR.

Alix Wan.