Audio singal input and output example for DISCO-F746. Input: MEMS mic, Output: CN10 OUT, Acoustic effect: echo and frequency shift. DISCO-F746 によるオーディオ信号入出力.入力:MEMS マイク,出力:CN10 OUT,音響効果:エコー,周波数変換.
Dependencies: F746_GUI F746_SAI_IO
MyAcousticEffector_MIC/Biquad.hpp
- Committer:
- MikamiUitOpen
- Date:
- 2017-04-10
- Revision:
- 10:56f2f01df983
- Parent:
- 8:9378fea59845
File content as of revision 10:56f2f01df983:
//-------------------------------------------------------------- // 縦続形 IIR フィルタで使う 1D タイプの 2 次のフィルタ // Biquad filter of 1D type for IIR filter of cascade structure // このクラスでは,係数は実行中に書き換えられることを想定している // // u[n] = x[n] + a1*u[n-1] + a2*u[n-2] // y[n] = u[n] + b1*u[n-1] + b2*u[n-2] // x[n] : input signal // y[n] : output signal // b0 = 1 // // 2017/03/26, Copyright (c) 2017 MIKAMI, Naoki //-------------------------------------------------------------- #ifndef IIR_BIQUAD_HPP #define IIR_BIQUAD_HPP #include "mbed.h" // 2nd order IIR filter namespace Mikami { class Biquad { public: struct Coefs { float a1, a2, b1, b2; }; Biquad(const Coefs ck = (Coefs){0, 0, 0, 0}) { SetCoefficients(ck); Clear(); } void SetCoefficients(const Coefs cf) { cf_ = cf; } float Execute(float xn) { float un = xn + cf_.a1*un1_ + cf_.a2*un2_; float yn = un + cf_.b1*un1_ + cf_.b2*un2_; un2_ = un1_; un1_ = un; return yn; } void Clear() { un1_ = un2_ = 0; } private: Coefs cf_; float un1_, un2_; // disallow copy constructor Biquad(const Biquad&); }; } #endif // IIR_BIQUAD_HPP