不韋 呂
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UIT2_IIR_Direct_double
IIR filter of direct form using double type operations and coefficients for ST Nucleo F401RE.
main.cpp
- Committer:
- MikamiUitOpen
- Date:
- 2014-11-12
- Revision:
- 5:41b9b4f4e6c0
- Parent:
- 3:cda783626037
- Child:
- 7:3889dd456ffa
File content as of revision 5:41b9b4f4e6c0:
//-------------------------------------------------------------- // IIR フィルタ,直接形,double で演算 // Analog Input : A0 // Analog Output: MCP4922 using SPI // 2014/11/12, Copyright (c) 2014 MIKAMI, Naoki //-------------------------------------------------------------- #include "mbed.h" #include "ADC_Base.hpp" // for ADC not using interrupt #include "DAC_MCP4922.hpp" // for DAC MCP4922 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 double am_[ORDER_] = { 5.684787115202E+00, -1.354501388127E+01, 1.731054054746E+01, -1.251297336508E+01, 4.850124049778E+00, -7.874837248679E-01}; const double bm_[ORDER_+1] = { 1.000028097647E-02, -5.466081078904E-02, 1.292315717890E-01, -1.691239024945E-01, 1.292315717890E-01, -5.466081078904E-02, 1.000028097647E-02}; const int FS_ = 12000; // Sampling frequency: 12 kHz ADC_Base adc_(A0, FS_); // for AD DAC_MCP4922 myDac_; // for DA int main() { myDac_.ScfClockTim3(500000); // cutoff frequency: 5 kHz double un[ORDER_]; // 過去の計算結果を格納する配列 for (int k=0; k<ORDER_; k++) un[k] = 0; while (true) { float xn = adc_.Read(); // Read from A0 //----------------------------------------------- double u0 = xn; for (int k=0; k<ORDER_; k++) u0 = u0 + am_[k]*un[k]; double yn = bm_[0]*u0; for (int k=0; k<ORDER_; k++) yn = yn + bm_[k+1]*un[k]; // 計算結果の移動 for (int k=ORDER_-1; k>0; k--) un[k] = un[k-1]; un[0] = u0; //----------------------------------------------- myDac_.Write((float)yn); // Write to DAC } }