不韋 呂
Output the audio signal with filtering by IIR filter in the *.wav file on the SD card using onboard CODEC. SD カードの *.wav ファイルのオーディオ信号を遮断周波数可変の IIR フィルタを通して，ボードに搭載されているCODEC で出力する．
Dependencies: BSP_DISCO_F746NG F746_GUI LCD_DISCO_F746NG SDFileSystem_Warning_Fixed TS_DISCO_F746NG mbed FrequencyResponseDrawer F746_SAI_IO Array_Matrix
Diff: MyClasses_Functions/BilinearDesignLH.hpp
- Revision:
- 0:04b43b777fae
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/MyClasses_Functions/BilinearDesignLH.hpp Tue Apr 19 09:46:11 2016 +0000
@@ -0,0 +1,60 @@
+//------------------------------------------------------------------------------
+// Design of Butterworth LPF and HPF using bilinear transform -- Header
+//
+// 2016/03/31, Copyright (c) 2016 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, b2; };
+ enum Type { LPF, HPF };
+
+ // Constructor
+ BilinearDesign(int order, float fs)
+ : PI_FS_(PI_/fs), ORDER_(order)
+ {
+ 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, Type pb, Coefs c[], float& g);
+
+ private:
+ static const float PI_ = 3.1415926536f;
+ const float PI_FS_;
+ const int ORDER_;
+
+ 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(Type pb);
+ void GetGain(Type pb);
+ void GetCoefs(Coefs c[], float& gain);
+ };
+}
+#endif // BILINEAR_BUTTERWORTH_HPP