RM0020 datasheet(50/69 Pages) STMICROELECTRONICS

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RM0020

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Equation 41

for each n = 0,1...N-1

The i-order filter is implemented using the cascade of m IIR filters of second-order:

Equation 42

Equation 43

Equation 44

for each n = 0,1...N-1

Performance: See Section 7 and Table 57.

Example 26. iir_float_casc

#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/*+4*/] ALIGN_MWERKS(8); /* +4 to ensure there are 16

bytes of readable memory behind y */

#ifdef __ghs__

#pragma alignvar (8)

#endif

ALIGN_DCC(8)

float s[3*4] ALIGN_MWERKS(8) = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};

float c[3*5]

= {0.3284466238F,

0.6596805377F,

0.3312418003F,

0.0639408215F,

0.0183196767F,

0.2531886900F,

0.5063763109F,

0.2531936959F,

0.0736238464F,

0.1725312505F,

0.4280607669F,

0.8524906977F,

0.4244401939F,

0.0998014847F,

0.5894355624F,};



xn

 b1

xn 1

–

 

xn i

–

 a1

yn 1

–



–

 ai

yn i

–



–



b10

x

 b11

x

–

 b12

x

–

 a11

y

–



–

a12

y

–



–



b20

y

 b21

y

–

 b22

y

–

 a21

y

–



–

a22

y

–



–





bm0

y

–

 bm1

y

–

 bm2

y

–

 am1

y

–



–

am2

y

–



–

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