Enabling PEQ block in SGTL5000

[sureshb]

Below configuration settings are done to enable PEQ in SGTL5000. 

DAP_CONTROL->DAP_EN = 1

DAP_PEQ->EN = 0x01

DAP_AUDIO_EQ->EN = 0x01

write the co-efficient registers for low pass filter with cut-off frequency 800Hz, [based on the attached "SGTL5000 PEQ design_12Jun2013_v3" sheet (set Cutoff Frequency FC = 800 Hz, set Sampling Frequency Fs= 8000Hz)]

DAP_FILTER_COEF_ACCESS->INDEX =0x01 

DAP_FILTER_COEF_ACCESS->WR=1

After doing the above configurations also we observe the frequency above 800Hz in the recorded file. 

Note: we are observing the frequency components in the recorded file by using Equalizer application (in Linux PC)

Please correct us if we are missing some configuration.

[xiangjun_rong]

Hi, Suresh,

You said that the you (set Cutoff Frequency FC = 800 Hz, set Sampling Frequency Fs= 8000Hz), but from the following curve, you draw the IIR filter Frequency response from the 0Hz to about 16670Hz, obviously, it violate the nyquist theorem, you can only see the frequency from 0Hz to 4KHz if you want to draw the frequency response based on sampling frequency of 8KHz.

Hope it can help you

BR

Xiangjun Rong