CQpub0 Mikami / Mbed 2 deprecated IIR_LPF

The experiment using this program is introduced on "Interface" No.2, CQ publishing Co.,Ltd, 2015. 本プログラムを使った実験は，CQ出版社のインターフェース 2015年2月号で紹介しています．

Dependencies:   DSProcessingIO mbed

Biquad.hpp@1:5ece9454ba73, 2014-07-29 (annotated)

Committer:
CQpub0Mikami
Date:
Tue Jul 29 06:55:48 2014 +0000
Revision:
1:5ece9454ba73
Parent:
0:398107c96b1b 
ver.2

Who changed what in which revision?

UserRevisionLine numberNew contents of line
CQpub0Mikami 0:398107c96b1b 1 //--------------------------------------------------------------
CQpub0Mikami 0:398107c96b1b 2 // Biquad filter for IIR filter of cascade structure
CQpub0Mikami 0:398107c96b1b 3 // Copyright (c) 2014 MIKAMI, Naoki, 2014/07/15
CQpub0Mikami 0:398107c96b1b 4 //--------------------------------------------------------------
CQpub0Mikami 0:398107c96b1b 5
CQpub0Mikami 0:398107c96b1b 6 #ifndef IIR_BIQUAD_HPP
CQpub0Mikami 0:398107c96b1b 7 #define IIR_BIQUAD_HPP
CQpub0Mikami 0:398107c96b1b 8
CQpub0Mikami 0:398107c96b1b 9 #include "mbed.h"
CQpub0Mikami 0:398107c96b1b 10
CQpub0Mikami 0:398107c96b1b 11 namespace Mikami
CQpub0Mikami 0:398107c96b1b 12 {
CQpub0Mikami 0:398107c96b1b 13 // 2nd order IIR filter
CQpub0Mikami 0:398107c96b1b 14 class Biquad
CQpub0Mikami 0:398107c96b1b 15 {
CQpub0Mikami 0:398107c96b1b 16 public:
CQpub0Mikami 0:398107c96b1b 17 struct Coefs { float a1, a2, b1, b2; };
CQpub0Mikami 0:398107c96b1b 18
CQpub0Mikami 0:398107c96b1b 19 Biquad() {} // Default constructore
CQpub0Mikami 0:398107c96b1b 20
CQpub0Mikami 0:398107c96b1b 21 Biquad(const Coefs ck)
CQpub0Mikami 0:398107c96b1b 22 : a1_(ck.a1), a2_(ck.a2), b1_(ck.b1), b2_(ck.b2)
CQpub0Mikami 0:398107c96b1b 23 { Clear(); }
CQpub0Mikami 0:398107c96b1b 24
CQpub0Mikami 0:398107c96b1b 25 float Execute(float xn)
CQpub0Mikami 0:398107c96b1b 26 {
CQpub0Mikami 0:398107c96b1b 27 float un = xn + a1_*un1_ + a2_*un2_;
CQpub0Mikami 0:398107c96b1b 28 float yn = un + b1_*un1_ + b2_*un2_;
CQpub0Mikami 0:398107c96b1b 29
CQpub0Mikami 0:398107c96b1b 30 un2_ = un1_;
CQpub0Mikami 0:398107c96b1b 31 un1_ = un;
CQpub0Mikami 0:398107c96b1b 32
CQpub0Mikami 0:398107c96b1b 33 return yn;
CQpub0Mikami 0:398107c96b1b 34 }
CQpub0Mikami 0:398107c96b1b 35
CQpub0Mikami 0:398107c96b1b 36 void Clear() { un1_ = un2_ = 0; }
CQpub0Mikami 0:398107c96b1b 37
CQpub0Mikami 0:398107c96b1b 38 private:
CQpub0Mikami 0:398107c96b1b 39 float a1_, a2_, b1_, b2_;
CQpub0Mikami 0:398107c96b1b 40 float un1_, un2_;
CQpub0Mikami 0:398107c96b1b 41
CQpub0Mikami 0:398107c96b1b 42 Biquad(const Biquad&);
CQpub0Mikami 0:398107c96b1b 43 };
CQpub0Mikami 0:398107c96b1b 44 }
CQpub0Mikami 0:398107c96b1b 45 #endif // IIR_BIQUAD_HPP