IIR filter of cascade form using Biquad class for ST Nucleo F401RE.
Dependencies: UITDSP_ADDA mbed
main.cpp
- Committer:
- MikamiUitOpen
- Date:
- 2014-10-23
- Revision:
- 3:8f384ccbbe66
- Parent:
- 1:ec14a181cab8
- Child:
- 5:14bb865c7eee
File content as of revision 3:8f384ccbbe66:
//-------------------------------------------------------------- // IIR フィルタ,縦続形,float で演算, Biquad クラス利用 // Analog Input : A0 // Analog Output: MCP4922 using SPI // 2014/10/23, Copyright (c) 2014 MIKAMI, Naoki //-------------------------------------------------------------- #include "mbed.h" #include "ADC_Base.hpp" // for ADC not using interrupt #include "DAC_MCP4922.hpp" // for DAC MCP4922 #include "ScfClockTim3.hpp" // for clock supplied to SCF #include "Biquad.hpp" // 2nd-ordered IIR filter using namespace Mikami; const int ORDER_ = 6; // order // 低域通過フィルタ // 連立チェビシェフ特性 // 次数 :6 次 // 標本化周波数: 12.00 kHz // 遮断周波数 : 0.40 kHz // 通過域のリップル: 0.50 dB // 阻止域の減衰量 :40.00 dB const Biquad::Coefs ck_[ORDER_/2] = { { 1.837790E+00f, -8.507293E-01f, -1.603320E+00f, 1.0E+00f}, // 1段目 { 1.904445E+00f, -9.382561E-01f, -1.919647E+00f, 1.0E+00f}, // 2段目 { 1.942552E+00f, -9.865720E-01f, -1.942961E+00f, 1.0E+00f}}; // 3段目 const float g0_ = 1.000028E-02f; // 利得定数 const int FS_ = 12000; // Sampling frequency: 12 kHz ADC_Base adc_(A0, FS_); // for AD DAC_MCP4922 myDac_; // for DA int main() { ScfClockTim3(500000); // cutoff frequency: 5 kHz Biquad hn[ORDER_/2]; for (int k=0; k<ORDER_/2; k++) hn[k] = Biquad(ck_[k]); while (true) { float xn = adc_.Read(); // Read from A0 //----------------------------------------------- float yn = g0_*xn; for (int k=0; k<ORDER_/2; k++) yn = hn[k].Execute(yn); //----------------------------------------------- myDac_.Write(yn); // Write to DAC } }