Part Number: PCM5121
Other Parts Discussed in Thread: TLV320ADC3140
The PCM5121 works good with sampling rate at 32000, with DSP program enable, and the DSP coefficiente generated by purepath.
But i really need to know how to generate this coefficients.
I have to equalize the output depending on the type of the speaker; it has to be a 3 band equalization.
I think to use 3 of the 6 input biquads.
If i want a minimum of 10 step per band i need 30!!! config table generated by purepath.
Since biquad on ADC (TLV320ADC3140) is tremendously easier; i tried the same approach:
- generate the coefficient as found in Audio-EQ-Cookbook.txt (400,2000,8000 center frequency)
- Convert coefficient int TI format ( N1 = (b1/a0)/2, D1 = (a1/a0)*(-1/2), D2 = (a2/a0)*(-1))
- normalize in -1,+1 range (useful for successive conversion)
- Convert to 4.20 format (i think multiply per 2^20)
- Multiply per 8 to enanche dynamic
- Write the coeffincient in the A page (tried adaptive mode but it doesn't work)
Result:
Very low volume with very high bandpass.
What i'missing?
Here there the only info available on biquad: Figure 57 on SLAS763C.pdf
