IIR Interface

Detailed Description

Interface for IIR filter functionality.

Summary

The IIR interface allows access to the IIRFA peripheral for hardware acceleration of direct form 2 transposed biquad IIR filters.

Data Structures
struct	iir_filter_coeffs_t
struct	iir_filter_state_t
struct	iir_filter_cfg_t
struct	iir_status_t
struct	iir_cfg_t
struct	iir_api_t
struct	iirfa_instance_t

Typedefs
typedef void	iir_ctrl_t

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Data Structure Documentation

iir_filter_coeffs_t

struct iir_filter_coeffs_t

Filter stage coefficient data

Data Fields
float	b0	Coefficient B0.
float	b1	Coefficient B1.
float	b2	Coefficient B2.
float	a1	Coefficient A0.
float	a2	Coefficient A1.

iir_filter_state_t

struct iir_filter_state_t

Filter stage state data

Data Fields
float	d0	State variable D0.
float	d1	State variable D1.

iir_filter_cfg_t

struct iir_filter_cfg_t

Filter configuration

Data Fields
iir_filter_coeffs_t *	p_filter_coeffs	Filter coefficients.
iir_filter_state_t *	p_filter_state	Filter state data.
uint8_t	stage_base	Hardware stage to start from.
uint8_t	stage_num	Number of filter stages to use.

iir_status_t

struct iir_status_t

Filter state register status

iir_cfg_t

struct iir_cfg_t

IIRFA API configuration parameter

Data Fields
void const *	p_extend
uint8_t	channel	IIRFA channel to use.

iir_api_t

struct iir_api_t

IIR driver structure. IIR functions implemented at the HAL layer follow this API.

Data Fields
fsp_err_t(*	open )(iir_ctrl_t *const p_ctrl, iir_cfg_t const *const p_cfg)
fsp_err_t(*	close )(iir_ctrl_t *const p_ctrl)
fsp_err_t(*	configure )(iir_ctrl_t *const p_ctrl, iir_filter_cfg_t const *const p_filter_cfg)
fsp_err_t(*	filter )(iir_ctrl_t *const p_ctrl, float const *p_data_in, float *p_data_out, uint16_t const num_samples)
fsp_err_t(*	statusGet )(iir_ctrl_t *const p_ctrl, iir_status_t *const p_status)

Field Documentation

open

fsp_err_t(* iir_api_t::open) (iir_ctrl_t *const p_ctrl, iir_cfg_t const *const p_cfg)

Initial configuration.

Parameters

[in]	p_ctrl	Pointer to control block. Must be declared by user. Elements set here.
[in]	p_cfg	Pointer to configuration structure. All elements of this structure must be set by user.

close

fsp_err_t(* iir_api_t::close) (iir_ctrl_t *const p_ctrl)

Close the IIRFA channel.

Parameters

[in]

p_ctrl

Control block set in iir_api_t::open.

configure

fsp_err_t(* iir_api_t::configure) (iir_ctrl_t *const p_ctrl, iir_filter_cfg_t const *const p_filter_cfg)

Configure filter coefficients and state variables.

Parameters

[in]	p_ctrl	Control block set in iir_api_t::open.
[in]	p_filter_cfg	Pointer to filter configuration to write.

filter

fsp_err_t(* iir_api_t::filter) (iir_ctrl_t *const p_ctrl, float const *p_data_in, float *p_data_out, uint16_t const num_samples)

Filter the specified data.

Parameters

[in]	p_ctrl	Control block set in iir_api_t::open.
[in]	p_data_in	Pointer to float input data.
[in]	p_data_out	Pointer to float output buffer.
[in]	num_samples	Number of samples to process.

statusGet

fsp_err_t(* iir_api_t::statusGet) (iir_ctrl_t *const p_ctrl, iir_status_t *const p_status)

Retrieve current status (including state registers).

Parameters

[in]	p_ctrl	Control block set in iir_api_t::open.
[in]	p_status	Pointer to status struct.

iirfa_instance_t

struct iirfa_instance_t

This structure encompasses everything that is needed to use an instance of this interface.

Data Fields
iir_ctrl_t *	p_ctrl	Pointer to the control structure for this instance.
iir_cfg_t const *	p_cfg	Pointer to the configuration structure for this instance.
iir_api_t const *	p_api	Pointer to the API structure for this instance.

Typedef Documentation

iir_ctrl_t

typedef void iir_ctrl_t

IIR control block. Allocate an instance specific control block to pass into the DAC API calls.