RM0020 datasheet(47/69 Pages) STMICROELECTRONICS

47 / 69 page

RM0020

Function API

47/69

Description:

Computes the first-order IIR filter on float data. The input samples are stored in the

array x, output samples are written to the array y.

Algorithm:

Equation 39

for each n from 0 to N-1

Performance: See Section 7 and Table 55.

Example 24. iir_float_1st

#include "libdsp2.h"

/* #pragma and ALIGN macros used to align to 8 bytes */

#ifdef __ghs__

#pragma alignvar (8)

#endif

ALIGN_DCC(8)

float x[256/*+4*/] ALIGN_MWERKS(8); /* +4 to ensure there are 16

bytes of readable memory behind x */

#ifdef __ghs__

#pragma alignvar (8)

#endif

ALIGN_DCC(8)

float y [256] ALIGN_MWERKS(8);

#ifdef __ghs__

#pragma alignvar (8)

#endif

ALIGN_DCC(8)

float s [2] ALIGN_MWERKS(8) = {0,0};

float c [3]

{0.5157131330F,0.5157131330F,0.0314262660F};

unsigned short N;

void main(void)

{

/* filter the samples in x with first-order IIR filter, */

/* write result into y */

N = 256;

iir_float_1st(N, x, y, c, s);

}

6.25

iir_float_2nd - float second-order IIR filter

Function call:

void iir_float_2nd (unsigned short N, float *x, float *y, float *c,

float *s);



xn

 b1

xn 1

–

 a1

yn 1

–



–

RM0020 Datasheet(PDF) 47 Page - STMicroelectronics

RM0020 Datasheet(HTML) 47 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69

Datasheet Download

Link URL