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Confusion of the "Crossover" module while changing its  filter type

Question asked by liangbread on Jul 15, 2014
Latest reply on Jul 21, 2014 by JJoseph

Hi John,


    I am running a "Crossover" module in my sigma studio project on ADSP-21489.And I got quite confused to control this module from the MCU during switching the different filter type to get different attenuation slope (12db/oct, 24db/oct,48db/oct and ect).


    When I choose "Linkwitz-Riley 12" as the filter type,only 11 parameters are needed to control the "Crossover module",while choosing the "Linkwitz-Riley 48",21 parameters are needed.As more parameters are needed I even found the parameter address overlapping to the other modules from the "capture" window.So I export the system files and refer to the exported files with the filter type of "Linkwitz-Riley 12" selected,from which,I don't find any more parameter address is pre-allocated for the other 10 parameters as needed in "Linkwitz-Riley 48".


     As with different filter type selected,there are overlapping and conflicting of the parameter addresses.I guess sigma studio doesn't send out the controlling parameters and parameter addresses.So I use the logic analyzer tool to capture the data sigma studio actually sending out after the filter type turned to "Linkwitz-Riley 48" from "Linkwitz-Riley 12".And that proves no any data sending out in this situation,even though,I can see that data seems to have been sent out from the "capture" window in sigma studio.What's more,even tuning other moduls no more controlling parameters are sending out from sigma studio ever since.It seems I have modified the project in sigma studio.To solve this problem,I have to  re-download the project.


    1)How can I use only one sigma studio project embedded into the application project in ldr file to use different filter type?

    2)As from the biquad transfer function as listed below,


                          1 + (b1/b0)*z^-1 + (b2/b0)*z^-2

  H(z) = (b0/a0) * -----------------------------------------------

                          1 + (a1/a0)*z^-1 + (a2/a0)*z^-2

     I am doubting could I build a project with filter type of "Linkwitz-Riley 48",and padding zero to the other parameters no used when "Linkwitz-Riley 12" is needed ?


Best Regards,