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Purepath Eq PPS PCM5142

hdfactor
Prodigy 220 points
Other Parts Discussed in Thread: PCM5142

We wish to perform Eq (with dynamic parameters) on the PCM5142.

1>The Parametric EQ and Graphic Eq does not seem to work at sample rates abouve 48K... (audio glitches out). Can we get these to operate up to 192Khz? If so how?

2>Another option we have is Biquads in the design... I note the High shelf has auto normalisation on the parameters that brings the gain down when high shelf gain is above 0dB - this makes the control system more complicated as I need to control the output gain when changing the eq parameters.  Can we turn of this auto parametrisation? Or is this simple a result of the GUI interface?

3>How can we use the Build  "Generate Driver Code" and .c and .h files to abstract the parameter change in code? Do you have a parameter change .c example for Biquad using the PCM5142?

4> Are there any updates for PPS (Home Audio) V5.95 build 1 22035 (component lib 6226)??

  • 0
    TI__Mastermind 27990 points

    Hi,

    1.To get 192kHz operation, you must enable it in the properties of the PCM5142 framework. To do this select the framework, and edit the properties shown below:

    2. When you say "High Shelf" filter, are you referring to the Treble shelf filter? This normalization is the result of the coefficient format. Since its in 1.23 format, it cannot go above the value 1. When setting a gain of 3 dB, this would send the coefficient over 1, if it did not normalize the filter gain. To avaid having to account for this, use the scale property on all filters to say a value of 0.1, this will set all the filters at the same level, and then you can tune your filters from there. Here is an app note taht touches on the subject: 

    3. When you generate the code, it should have all the registers you need to write to implement the signal flow you created. Are you asking for a way to change the coefficients after the initial setup?

    4. PPS 5.95 is the latest build.

    Justin

  • 0 in reply to Justin Bohr
    Prodigy 220 points

    Hi Justin...

     

    1. Yes we are aware of the need to set 192khz support here. The problem seems to be that the MiniDsp cannot run the 5band Eq at 192kz even when the support is enabled... we have tried this on our 5412EVM - can you confirm on Eval that 5band works at 96kHz or 192khz?

     

    2.Thanks. The Bass Shelf does not normalise but the Treble Shelf does… why is this?

    So with scale of 0.1 the base gain of the filter will be reduced. To make up the gain is there a component in PPS that adds gain (above 6 or 12dB) other than the Volume Component?

      2311.pps_drvr.zip

    3. We need to change the coefficients after the initial setup. These are to be set while operating/runtime like any Eq of a HiFi system. We have used in the past the .h file for sending coefficients to the PCM5142 however these is quite involved... instead of this we would like to use the pps_driver.c pps_driver.h file and call the internal routines... we hope you will have an application example using pps_driver that shows how to call the functions in a real-time system? I have attached the pps generated pps_driver files from our project as an example...