This version (18 May 2021 09:03) was approved by John Joseph.The Previously approved version (02 Mar 2020 07:58) is available.Diff

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2nd Order Index Selectable


The General (2nd-Order / Index Selectable) block provides a wide variety of 2nd-order filter algorithms. This block extends the functionality of the General (2nd-Order / Lookup) filter with an enhanced graphical filter design tool. In addition, each of this filter's response curves can be designed independently, allowing you to use complex filter configurations to match your desired system response.


To open the graphical window, click on the icon button. This filter provides:

Selection from a set of filter responses via external control input pin. Graphical design of filter response curves. Independent filter type and settings for each response curve. Loading of filter coefficients from a text file containing the same.

Targets Supported

Name ADSP-214xx ADSP-215xx/SC5xx ADAU145x/146x
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2nd Order Index Selectable B/S B/S S



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ControlInputControlIndex of the selected frequency response curve
Input0AudioInput to the filter


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Output0AudioThe filtered output

Configurable Parameters

GUI Parameter NameDefault ValueRangeFunction Description
NumFilters00 to 99Selects a filter response curve by filter number selected
SlewPoints120 to 100The “Slew Points” control sets how many transition points the algorithm uses to transition from one selected filter curve to another, increasing the number of points will provide smoother transitions.
FilterType_Filter000 to 13Select the type of filter
SubType1_Filter000 to 3The “Sub Type” section is only available for the First Order filter type. In first order mode, you have the flexibility of choosing between two cascaded first order filters in a configuration of Low - Low, Low - High, High - Low, or High - High combinations. The “Active 1” and “Active 2” check boxes also apply to First Order filters only, and allow you to independently enable or disable either of the two first order filters.
Boost_Filter010 dB -150 to +30 dBSet the boost value for a particular filter curve
Frequency1_Filter0100 Hz0 to 96000HzCut-off frequency
Frequency2_Filter01000 Hz0 to 96KHzCut-off frequency
Gain1_Filter06 dB-96 to +10 dBFilter Gain
Gain2_Filter0 dB-96 to +10 dBFilter Gain
QFactor_Filter01.410.05 to 15Q factor of the filter
Ripple_Filter00.10.1 to 5Set the Ripple factor for particular filter type(this control is not enabled for all filter types)
Slope10 to 2Slope controls filter steepness and therefore the transition between the boost/cut and the flat response.
FilterTypeParametric filterAvailable filter TypesControls the type of the filter
EnabledOrBypassedTrueTrue/FalseEnabled/Disabled the algorithm
PhaseFalseTrue/FalseControls the phase of coefficients in 0 degree or 180 degree phase
LockFrequencyFalseTrue/FalseEnabled/Disabled locks the frequency control
NumStages11 to 20 Number of stages of filter. Change in this value requires re-compilation
NumChannels1 1 to 20Number of input and output channels. Change in this value requires re-compilation

DSP Parameters

Parameter Name Description ADSP-214xx/SC5xx/215xx ADAU145x/146x
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GainArrayFilter Coefficient Array consisting of all filter coefficientsFloatFixPoint8d24
slew_modeSlew value for the filterNAInteger32
resources/tools-software/sigmastudiov2/modules/filters/generalsecondorderindexselectable.txt · Last modified: 12 May 2021 20:33 by Sreesha Y M