Cutoff frequency variable LPF by IIR 6th-order Butterworth filter for ST Nucleo F401RE.
Dependencies: UIT_IIR_Filter UIT_ACM1602NI UITDSP_ADDA mbed UIT_AQM1602
BilinearDesignLpfHpf/BilinearDesignLH.hpp
- Committer:
- MikamiUitOpen
- Date:
- 2015-09-11
- Revision:
- 7:34eced3597bb
- Parent:
- 5:b291c4653eb9
File content as of revision 7:34eced3597bb:
//------------------------------------------------------------------------------ // Design of Butterworth LPF and HPF using bilinear transform -- Header // // 2014/06/29, Copyright (c) 2014 MIKAMI, Naoki //------------------------------------------------------------------------------ #ifndef BILINEAR_BUTTERWORTH_HPP #define BILINEAR_BUTTERWORTH_HPP #include "mbed.h" #include <complex> // requisite namespace Mikami { typedef complex<float> Complex; // define "Complex" class BilinearDesign { public: struct Coefs { float a1, a2, b1; }; enum Type { LPF, HPF }; // Constructor BilinearDesign(int order, float fs, Type pb) : PI_FS_(PI_/fs), ORDER_(order), PB_(pb) { sP_ = new Complex[order/2]; zP_ = new Complex[order/2]; ck_ = new Coefs[order/2]; } // Destractor ~BilinearDesign() { delete[] sP_; delete[] zP_; delete[] ck_; } // Execution of design void Execute(float fc, Coefs c[], float& g); private: static const float PI_ = 3.1415926536f; const float PI_FS_; const int ORDER_; const Type PB_; Complex* sP_; // Poles on s-plane Complex* zP_; // Poles on z-plane Coefs* ck_; // Coefficients of transfer function for cascade form float gain_; // Gain factor for cascade form void Butterworth(); void Bilinear(float fc); void ToCascade(); void GetGain(); void GetCoefs(Coefs c[], float& gain); }; } #endif // BILINEAR_BUTTERWORTH_HPP