Aviate::IirBiQuadFilter Class Reference

IIR BiQuad Filter - Direct Form I
y[n] = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2]
Some design tools (like Matlab assume the feedback coefficients 'a' are negated. More...

#include <LibBasicFunctions.h>

Public Member Functions
	IirBiQuadFilter (unsigned numStages, const int32_t *coeffs, int coeffShift=0)
	Construct a Biquad filter with specified number of stages, coefficients and scaling. More...
virtual	~IirBiQuadFilter ()
	Destructor.
void	changeFilterCoeffs (unsigned numStages, const int32_t *coeffs, int coeffShift=0)
	Reconfigure the filter coefficients. More...
bool	process (int16_t *output, int16_t *input, size_t numSamples)
	Process the data using the configured IIR filter. More...

Detailed Description

IIR BiQuad Filter - Direct Form I
y[n] = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2]
Some design tools (like Matlab assume the feedback coefficients 'a' are negated.

You may have to negate your 'a' coefficients.

Note that the ARM CMSIS-DSP library requires an extra zero between first and second 'b' coefficients. E.g.
{b10, 0, b11, b12, a11, a12, b20, 0, b21, b22, a21, a22, ...}

Constructor & Destructor Documentation

IirBiQuadFilter()

Aviate::IirBiQuadFilter::IirBiQuadFilter	(	unsigned	numStages,
		const int32_t *	coeffs,
		int	coeffShift = 0
	)

Construct a Biquad filter with specified number of stages, coefficients and scaling.

See CMSIS-DSP documentation for more details

Parameters

numStages	number of biquad stages. Each stage has 5 coefficients.
coeffs	pointer to an array of Q31 fixed-point coefficients (range -1 to +0.999...)
coeffShift	coeffs are multiplied by 2^coeffShift to support coefficient range scaling

Member Function Documentation

changeFilterCoeffs()

void Aviate::IirBiQuadFilter::changeFilterCoeffs	(	unsigned	numStages,
		const int32_t *	coeffs,
		int	coeffShift = 0
	)

Reconfigure the filter coefficients.

See CMSIS-DSP documentation for more details

Parameters

numStages	number of biquad stages. Each stage has 5 coefficients.
coeffs	pointer to an array of Q31 fixed-point coefficients (range -1 to +0.999...)
coeffShift	coeffs are multiplied by 2^coeffShift to support coefficient range scaling

process()

bool Aviate::IirBiQuadFilter::process	(	int16_t *	output,
		int16_t *	input,
		size_t	numSamples
	)

Process the data using the configured IIR filter.

output and input can be the same pointer if in-place modification is desired

Parameters

output	pointer to where the output results will be written
input	pointer to where the input data will be read from
numSamples	number of samples to process

Returns

true if successful, false if an error occurs

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The documentation for this class was generated from the following file:

• inc/LibBasicFunctions.h