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

Committer:
CQpub0Mikami
Date:
2014-07-29
Revision:
1:5ece9454ba73
Parent:
0:398107c96b1b

File content as of revision 1:5ece9454ba73:

//--------------------------------------------------------------
// Biquad filter for IIR filter of cascade structure
// Copyright (c) 2014 MIKAMI, Naoki, 2014/07/15
//--------------------------------------------------------------

#ifndef IIR_BIQUAD_HPP
#define IIR_BIQUAD_HPP

#include "mbed.h"

namespace Mikami
{
    // 2nd order IIR filter
    class Biquad
    {
    public:
        struct Coefs { float a1, a2, b1, b2; };

        Biquad() {}     // Default constructore
 
        Biquad(const Coefs ck)
            : a1_(ck.a1), a2_(ck.a2), b1_(ck.b1), b2_(ck.b2)
        { Clear(); }       

        float Execute(float xn)
        {
            float un = xn + a1_*un1_ + a2_*un2_;
            float yn = un + b1_*un1_ + b2_*un2_;
            
            un2_ = un1_;
            un1_ = un;
            
            return yn;
        }
 
        void Clear() { un1_ = un2_ = 0; }
 
    private:
        float a1_, a2_, b1_, b2_;
        float un1_, un2_;
 
        Biquad(const Biquad&);
    };
}
#endif  // IIR_BIQUAD_HPP