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TLV320AIC33: Using TIBQ.exe with TLV320AIC33

Randy Hermes
Prodigy 170 points
Part Number: TLV320AIC33

Are instructions available for using the coefficients generated by TIBQ with the TLV320AIC33 codec?

In particular, TIBQ generates N0,N1,D1 or N0,N1,N2,D1,D2 coefficients. 

My filter (20Hz Hi Pass, 10KHz Low Pass) generated two sets of N0,N1,D1. I programmed these in and set N2,D2 = 0.  Did not produce good results.

Thanks,

Randy.

  • 0
    TI__Mastermind 30030 points

    Randy,

    are you wanting single order filters?  Try using the Butterworth 2 subtype in TIBQ to get the biquad coefficients.  The Biquad 1 is meant for the single order HPF.

    The reason why you're having issues, is because you can't just set N2, D2= 0 .  You also have to Scale N1 and D1 by 1/2.  See the equation for the biquad in the datasheet.

    you can See that there is a factor of 2 that you need to account for.   I have tested this on an EVM, and If you scale your N1 and D1 values it works.  So if you want the 1st order filter,  you can do that. 

    best regards,

    -Steve Wilson

  • 0 in reply to Steve-Wilson
    Prodigy 170 points
    Thanks Steve,

    I will try this on Monday.
    I also tried the Butterworth 2 filter which generated complete bi-quad coefficients. When I run this filter I get nothing out of the CODEC.
    Right now I'm running on our target system. I also intend to get a EVM so I can use the software supplied with it.

    I'll let you know how things work out next week.
  • 0 in reply to Randy Hermes
    TI__Mastermind 30030 points
    no problem Randy, Let me know how it goes. Just to confirm your configuration. You are also enabling the filter in register 12 correct?
    now the biquad Coefficients are 32 bits, and the registers must be written consecutively MSB register to LSB register. The Coefficients should also be written before the DAC is powered up.

    if you want to pass along your register configuration sequence, I can comment more specifically.

    best regards,
    -Steve Wilson
  • 0 in reply to Randy Hermes
    TI__Mastermind 30030 points
    Hello Randy,

    I thought that I would check in with you to see how your configuration is going. Are you still experiencing problems?

    best regards,
    -Steve Wilson
  • 0 in reply to Steve-Wilson
    Prodigy 170 points

    Thanks for checking Steve,

    Didn't get to it yesterday.  Will let you know as soon as I do.

    Randy

  • 0 in reply to Steve-Wilson
    Prodigy 170 points
    Hi Steve,

    Got the filter working today, thanks for the help. BTW the coefficients for the TLV320AIC33 are 16 bits, not 32 bit as you stated previously.
    Turns out my biggest issues was incorrect byte order, I expected LSB, MSB so I saw LSB, MSB in the docs. My bad.

    One other question. We are seeing quite a bit of 3MHz noise on the CODEC outputs. The Effects filter is not reducing this at all.
    Is this normal and requires a filter on the output or is it likely something with our implementation?

    Thanks
    Randy