1. I am trying to set a 4th-order notch filter using Pure Path using the cascaded biquads block.
I was able to make this filter work for primary AIS interface of tlv320aic3254 chip. Attched below are Mag vs frequency responses of
recorded audio on primary interface.
Without Notch Filter :
With Notch Filter at 4.2Khz:
2. I have trouble getting this filter work for the Secondary AIS interface of tlv320aic3254.
I do get audio on this Interface, but the frequency response shows that the filtering action has not taken place !!!
i.e. I don't see a dip at 4.2Khz in the Mag vs Frequency response.
3. I have no clue as what is going wrong.
I have attached the Pure Path text scripts (which I have modified to suit my hardware) using for primary and secondary AIS interface.
Can someone please help in reviewing this script, particularly for the secondary interface.
I am not sure above scripts are sufficient to debug the problem, please do inform if any further details are needed.
Has anybody been able to use miniDSP and get filtered audio on Secondary Interface ?
If yes then please share the register settings/ script used to do so, it will be of great help.
We are looking into your question.
Audio Applications Engineering Manager
Dallas, TX USA
Hi,This time I have tried to avoid the miniDSP and use the ADC processing block 2 instead, which offers 5 cascaded biquads. I made use of Biquad A and Biquad B to form a 4th order notch filter at 4300Hz, and used Biquad Coefficient calculator by TI. Again here, I observe, the filtering action happening only for primary interface and not on secondary interface. It seems to me that I am not properly configuring the Secondary interface.Please can you review the script below, No miniDSP involved here, ADC processing block 2 is used :3632.audiochip_secondary_notch4300.txt // Notch filter for 4300Hz, 48Khz sampling frequency, Master_clock12.288 Mhz, Word_clock = 48Khz, bit_clock = 3Mhz biquad_coefficients = 0x7E 0x58 0x95 0x00 0x95 0x25 0x4A 0x00 0x7E 0x58 0x95 0x00 0x6A 0xDA 0xB6 0x00 0x83 0x4E 0xD5 // Software Reset w 0x30 0x00 0x00 // Select PAGE 0 w 0x30 0x01 0x01 // Initializ Device through software reset // Power Supply Configuration w 0x30 0x00 0x01 // Select PAGE 1 w 0x30 0x02 0x09 // Power up ALDO w 0x30 0x01 0x08 // Disable Weak Avdd & connect it to Dvdd w 0x30 0x02 0x01 // Keep ALDO Powered enable master analog power control w 0x30 0x47 0x32 // Set input power-up to 3.1 msec w 0x30 0x7b 0x01 // Set REF chargup to 40 msec
// Clock Configuration w 0x30 0x00 0x00 // Select PAGE 0 w 0x30 0x04 0x0f // pll_input = Din & Codec_Clk = pll_clk w 0x30 0x06 0x07 // J = 7 w 0x30 0x05 0x91 // P = R = 1 & Power-up w 0x30 0x0b 0x02 // NDAC = 2 & Power-down w 0x30 0x0c 0x07 // MDAC = 7 & Power-down w 0x30 0x12 0x82 // NADC = 2 & Power-up w 0x30 0x13 0x87 // MADC = 7 & Power-up // Secondary Interface Configuration w 0x30 0x00 0x00 // Select PAGE 0 w 0x30 0x34 0x04 // Seconday Wclk = MFP5 w 0x30 0x37 0x10 // Secondary Output = MFP4 w 0x30 0x1f 0x20 // Secondary MUX for Wclk = GPIO/MFP5 & Secondary MUX for Bclk = SCLK/MFP3 w 0x30 0x20 0x0e // AIS will use secondary interface settings w 0x30 0x21 0x3d // Secondary Data output from Serial Interface w 0x30 0x1d 0x04 // Force AIS output the respective secondary clks w 0x30 0x1b 0x20 // 24-Bit format on I2S w 0x30 0x00 0x01 // Select PAGE 1 w 0x30 0x0a 0x7b // 0.75 V common mode // ADC Configuration w 0x30 0x00 0x00 // Select PAGE 0 w 0x30 0x3d 0x02 // Processing block 2 for ADC IIR with flat response
// 4TH Order Notch w 0x30 0x00 0x08 // Select PAGE 8 w 0x30 0x24 biquad_coefficients 19 bytes w 0x30 0x38 biquad_coefficients 19 bytes w 0x30 0x00 0x09 // Select PAGE 9 w 0x30 0x2c biquad_coefficients 19 bytes w 0x30 0x40 biquad_coefficients 19 bytes
w 0x30 0x00 0x01 // Select PAGE 1 w 0x30 0x3d 0x64 // ADC PowerTuneMode 3 w 0x30 0x33 0x58 // Mic Bias 1.45 V w 0x30 0x34 0x10 // IN2L to positive of LPGA w 0x30 0x36 0x10 w 0x30 0x37 0x04 // IN3R to positive of RPGA w 0x30 0x39 0x04 w 0x30 0x3b 0x2c // unmute LPGA with gain of 22dB w 0x30 0x3c 0x2c // unmute RPGA with gain of 22dB // Power up ADC & DAC w 0x30 0x00 0x00 // Select PAGE 0 w 0x30 0x51 0xc0 // Power up LADC and RADC w 0x30 0x52 0x00 // Unmute LADC & RADC gain is 0dbThanks,
How are you measuring the signal exactly? We can discuss this offline if you'd like. I'll send you a friend request
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