IIR filter of cascade form using Biquad class for ST Nucleo F401RE.
Dependencies: UITDSP_ADDA mbed
main.cpp@3:8f384ccbbe66, 2014-10-23 (annotated)
- Committer:
- MikamiUitOpen
- Date:
- Thu Oct 23 00:27:39 2014 +0000
- Revision:
- 3:8f384ccbbe66
- Parent:
- 1:ec14a181cab8
- Child:
- 5:14bb865c7eee
4
Who changed what in which revision?
User | Revision | Line number | New contents of line |
---|---|---|---|
MikamiUitOpen | 0:24c904911225 | 1 | //-------------------------------------------------------------- |
MikamiUitOpen | 0:24c904911225 | 2 | // IIR フィルタ,縦続形,float で演算, Biquad クラス利用 |
MikamiUitOpen | 0:24c904911225 | 3 | // Analog Input : A0 |
MikamiUitOpen | 0:24c904911225 | 4 | // Analog Output: MCP4922 using SPI |
MikamiUitOpen | 3:8f384ccbbe66 | 5 | // 2014/10/23, Copyright (c) 2014 MIKAMI, Naoki |
MikamiUitOpen | 0:24c904911225 | 6 | //-------------------------------------------------------------- |
MikamiUitOpen | 0:24c904911225 | 7 | |
MikamiUitOpen | 0:24c904911225 | 8 | #include "mbed.h" |
MikamiUitOpen | 0:24c904911225 | 9 | |
MikamiUitOpen | 0:24c904911225 | 10 | #include "ADC_Base.hpp" // for ADC not using interrupt |
MikamiUitOpen | 0:24c904911225 | 11 | #include "DAC_MCP4922.hpp" // for DAC MCP4922 |
MikamiUitOpen | 0:24c904911225 | 12 | #include "ScfClockTim3.hpp" // for clock supplied to SCF |
MikamiUitOpen | 0:24c904911225 | 13 | #include "Biquad.hpp" // 2nd-ordered IIR filter |
MikamiUitOpen | 0:24c904911225 | 14 | |
MikamiUitOpen | 0:24c904911225 | 15 | using namespace Mikami; |
MikamiUitOpen | 0:24c904911225 | 16 | |
MikamiUitOpen | 0:24c904911225 | 17 | const int ORDER_ = 6; // order |
MikamiUitOpen | 0:24c904911225 | 18 | |
MikamiUitOpen | 0:24c904911225 | 19 | // 低域通過フィルタ |
MikamiUitOpen | 0:24c904911225 | 20 | // 連立チェビシェフ特性 |
MikamiUitOpen | 0:24c904911225 | 21 | // 次数 :6 次 |
MikamiUitOpen | 0:24c904911225 | 22 | // 標本化周波数: 12.00 kHz |
MikamiUitOpen | 0:24c904911225 | 23 | // 遮断周波数 : 0.40 kHz |
MikamiUitOpen | 0:24c904911225 | 24 | // 通過域のリップル: 0.50 dB |
MikamiUitOpen | 0:24c904911225 | 25 | // 阻止域の減衰量 :40.00 dB |
MikamiUitOpen | 0:24c904911225 | 26 | const Biquad::Coefs ck_[ORDER_/2] = { |
MikamiUitOpen | 1:ec14a181cab8 | 27 | { 1.837790E+00f, -8.507293E-01f, -1.603320E+00f, 1.0E+00f}, // 1段目 |
MikamiUitOpen | 1:ec14a181cab8 | 28 | { 1.904445E+00f, -9.382561E-01f, -1.919647E+00f, 1.0E+00f}, // 2段目 |
MikamiUitOpen | 1:ec14a181cab8 | 29 | { 1.942552E+00f, -9.865720E-01f, -1.942961E+00f, 1.0E+00f}}; // 3段目 |
MikamiUitOpen | 0:24c904911225 | 30 | const float g0_ = 1.000028E-02f; // 利得定数 |
MikamiUitOpen | 0:24c904911225 | 31 | |
MikamiUitOpen | 3:8f384ccbbe66 | 32 | const int FS_ = 12000; // Sampling frequency: 12 kHz |
MikamiUitOpen | 3:8f384ccbbe66 | 33 | ADC_Base adc_(A0, FS_); // for AD |
MikamiUitOpen | 3:8f384ccbbe66 | 34 | DAC_MCP4922 myDac_; // for DA |
MikamiUitOpen | 0:24c904911225 | 35 | |
MikamiUitOpen | 0:24c904911225 | 36 | int main() |
MikamiUitOpen | 0:24c904911225 | 37 | { |
MikamiUitOpen | 0:24c904911225 | 38 | ScfClockTim3(500000); // cutoff frequency: 5 kHz |
MikamiUitOpen | 0:24c904911225 | 39 | |
MikamiUitOpen | 0:24c904911225 | 40 | Biquad hn[ORDER_/2]; |
MikamiUitOpen | 0:24c904911225 | 41 | for (int k=0; k<ORDER_/2; k++) |
MikamiUitOpen | 0:24c904911225 | 42 | hn[k] = Biquad(ck_[k]); |
MikamiUitOpen | 0:24c904911225 | 43 | |
MikamiUitOpen | 0:24c904911225 | 44 | while (true) |
MikamiUitOpen | 0:24c904911225 | 45 | { |
MikamiUitOpen | 0:24c904911225 | 46 | float xn = adc_.Read(); // Read from A0 |
MikamiUitOpen | 0:24c904911225 | 47 | //----------------------------------------------- |
MikamiUitOpen | 0:24c904911225 | 48 | |
MikamiUitOpen | 0:24c904911225 | 49 | float yn = g0_*xn; |
MikamiUitOpen | 0:24c904911225 | 50 | for (int k=0; k<ORDER_/2; k++) |
MikamiUitOpen | 0:24c904911225 | 51 | yn = hn[k].Execute(yn); |
MikamiUitOpen | 0:24c904911225 | 52 | |
MikamiUitOpen | 0:24c904911225 | 53 | //----------------------------------------------- |
MikamiUitOpen | 0:24c904911225 | 54 | myDac_.Write(yn); // Write to DAC |
MikamiUitOpen | 0:24c904911225 | 55 | } |
MikamiUitOpen | 0:24c904911225 | 56 | } |
MikamiUitOpen | 0:24c904911225 | 57 | |
MikamiUitOpen | 0:24c904911225 | 58 |