This version (18 May 2021 09:04) was approved by Sreesha Y M.

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General 2nd Order with Var Param Lookup Slew


The General (2nd-Order / Lookup) block gives access to a wide variety of 2nd-order IIR (infinite impulse response) filter algorithms. See General 2nd-Order Filters (in Algorithm Information) for details about the algorithms driving these blocks.

The filters available are: Tone Peaking General LP/HP Butterworth LP/HP Bessel LP/HP Chebyshev LP/HP

The block is simply a double-precision biquad filter that has stored a set of coefficients in tables in the DSP. To select curves (lookup), use an Index Lookup Table, a Counter block, or a DC Input block in your design and connect it to the red pin.


Click the icon button:. The curve is defined using the Tone Control window (shown above).

Enter the number of curves desired in the # Curves field. Enter Boosts, (overall) Gain, and Q in their fields. Enter the desired cutoff or center (peaking filters) frequency in the Frequency fields. Other parameters to enter will vary with filter type.

The variety and range of filters are remarkable, as can be seen from the many examples in the General (2nd-Order / Lookup) topic page.

Targets Supported

Name ADSP-214xx ADSP-215xx/SC5xx ADAU145x/146x
————————- ——————-- ——————————-- —————————-
Parametric EQ B/S B/S S



—————————— —————————— ————————————————
ControlInputControlFilter Index Selection
Input0AudioInput to the filter


—————————— —————————— ————————————————
Output0AudioThe filtered output

Configurable Parameters

GUI Parameter NameDefault ValueRangeFunction Description
NumCurves42 to 50The number of curves desired from which a particular filter can be selected
FilterType00 to 5Select the type of filter
SubType00 and 1The “Sub Type” section is only available for butterworth, chebyshev and bessel filter types. The subtype selects either high or low pass.
BoostMax-10 dB -20 to +20 dBSet the maximum value for boost
BoostMin10 dB -20 to +20 dBSet the minimum value for boost
FrequencyMax100 Hz0 to 96kHzThe maximum value of frequency
FrequencyMin300 Hz0 to 96kHzThe minimum value of frequency
Gain-5 dB-20 to +20 dBFilter Gain
QFactor0.7070.01 to 10Q factor of the filter
Ripple0.10.1 to 5Set the Ripple factor for filter. Available only for Chebyshev type
NumChannels1 1 to 20Number of input and output channels. Change in this value requires re-compilation
SlewPoints125 to 22The “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.

DSP Parameters

Parameter Name Description ADSP-214xx/SC5xx/215xx ADAU145x/146x
———————————— —————————————————————————-- —————————————- —————————-
FilterCoefficientsArrayFilter Coefficient Array consisting of all filter coefficients
along with slew rate values
slew_modeFilter Slew ValueNAInteger32
resources/tools-software/sigmastudiov2/modules/filters/gsowvarparamlookupslew.txt · Last modified: 13 May 2021 14:27 by Sreesha Y M