不韋 呂
/
UIT2_IIR_Direct_float
IIR filter of direct form using float type operations and coefficients for ST Nucleo F401RE.
main.cpp
- Committer:
- MikamiUitOpen
- Date:
- 2014-10-20
- Revision:
- 0:3797037e0936
- Child:
- 1:bb0320fb8ad1
File content as of revision 0:3797037e0936:
//-------------------------------------------------------------- // IIR フィルタ,直接形,float で演算 // Analog Input : A0 // Analog Output: MCP4922 using SPI // 2014/10/20, Copyright (c) 2014 MIKAMI, Naoki //-------------------------------------------------------------- #include "mbed.h" #include "ADC_Interrupt.hpp" // for ADC using interrupt #include "DAC_MCP4922.hpp" // for DAC MCP4922 #include "ScfClockTim3.hpp" // for clock supplied to SCF using namespace Mikami; const int ORDER_ = 8; // 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 float am_[ORDER_] = { 5.684787115202E+00, -1.354501388127E+01, 1.731054054746E+01, -1.251297336508E+01, 4.850124049778E+00, -7.874837248679E-01}; const float 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_(DAC_MCP4922::DAC_A); // for DA int main() { ScfClockTim3(500000); // cutoff frequency: 5 kHz float 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 //----------------------------------------------- float u0 = xn; for (int k=0; k<ORDER_; k++) u0 = u0 + am_[k]*un[k]; float 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(yn); // Write to DAC } }