Revision 0:a5a171eda3f8, committed 2014-07-15

Comitter:

CQpub0Mikami

Date:

Tue Jul 15 09:11:35 2014 +0000

Child:

1:1c24d4ad5f4e

Commit message:

1

Changed in this revision

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Biquad.hpp	Tue Jul 15 09:11:35 2014 +0000
@@ -0,0 +1,45 @@
+//--------------------------------------------------------------
+// Biquad filter for IIR filter of cascade structure
+// Copyright (c) 2014 MIKAMI, Naoki, 2014/07/15
+//--------------------------------------------------------------
+
+#ifndef IIR_BIQUAD_HPP
+#define IIR_BIQUAD_HPP
+
+#include "mbed.h"
+
+namespace Mikami
+{
+    // 2nd order IIR filter
+    class Biquad
+    {
+    public:
+        struct Coefs { float a1, a2, b1, b2; };
+
+        Biquad() {}     // Default constructore
+ 
+        Biquad(const Coefs ck)
+            : a1_(ck.a1), a2_(ck.a2), b1_(ck.b1), b2_(ck.b2)
+        { Clear(); }       
+
+        float Execute(float xn)
+        {
+            float un = xn + a1_*un1_ + a2_*un2_;
+            float yn = un + b1_*un1_ + b2_*un2_;
+            
+            un2_ = un1_;
+            un1_ = un;
+            
+            return yn;
+        }
+ 
+        void Clear() { un1_ = un2_ = 0; }
+ 
+    private:
+        float a1_, a2_, b1_, b2_;
+        float un1_, un2_;
+ 
+        Biquad(const Biquad&);
+    };
+}
+#endif  // IIR_BIQUAD_HPP

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/DC_Cut_Coefficients.hpp	Tue Jul 15 09:11:35 2014 +0000
@@ -0,0 +1,17 @@
+//--------------------------------------------------------------
+//  Coefficients for IIR filter, Order = 2
+//--------------------------------------------------------------
+// Highpass filter
+// Butterworth filter
+// Sampling frequency:     10.00 kHz
+// Cutoff frequency:        0.05 kHz
+// Ripples in passband:     0.50 dB
+
+#include "Biquad.hpp"
+
+using namespace Mikami;
+
+const Biquad::Coefs c1_ =
+    { 1.955578E+00f, -9.565437E-01f, -2.0f, 1.0f};
+const float g0_ = 9.780305E-01f;
+

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/DSProcessingIO.lib	Tue Jul 15 09:11:35 2014 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/CQpub0Mikami/code/DSProcessingIO/#c3f647a89947

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/FreqConv.cpp	Tue Jul 15 09:11:35 2014 +0000
@@ -0,0 +1,46 @@
+//--------------------------------------------------------------
+// Frequency converter
+// Copyright (c) 2014 MIKAMI, Naoki,  2014/06/23
+//--------------------------------------------------------------
+
+#include "mbed.h"
+#include "AdcInternal.hpp"
+#include "MCP4922Single.hpp"
+#include "HilbertTransform.hpp"
+#include "coefsHilbert94.hpp"
+#include "DC_Cut_Coefficients.hpp"
+#include "Biquad.hpp"
+#include "TwoPhaseGenerator.hpp"
+
+using namespace Mikami;
+
+const float FS_ = 10.0e3f;
+Adc adc_(A0);
+Dac dac_(Dac::DAC_A);
+
+Ticker timer_;          // for timer interrupt
+
+Hilbert<ORDER_> ht(hm_);
+Biquad DcCut(c1_);      // DC cut filter
+TwoPhaseGenerator sinCos_(100.0f, FS_); // 100.0 Hz
+
+void TimerIsr()
+{
+    float yI, yQ, cosx, sinx;
+
+    float xn = adc_.Read(); // input
+    
+    xn = DcCut.Execute(g0_*xn);     // DC cut
+    ht.Execute(xn, yI, yQ);         // Hilbert transform
+    sinCos_.Generate(cosx, sinx);   // cos and sin generator
+    float yn = yI*cosx - yQ*sinx;   // conversion
+    
+    dac_.Write(yn);    // output
+}
+
+int main()
+{
+    timer_.attach_us(&TimerIsr, 1.0e6f/FS_);
+    while (true) {}    // infinite loop
+}
+

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/HilbertTransform.hpp	Tue Jul 15 09:11:35 2014 +0000
@@ -0,0 +1,44 @@
+//--------------------------------------------------------------
+// Hilbert transform filter
+// Copyright (c) 2014 MIKAMI, Naoki,  2014/06/23
+//--------------------------------------------------------------
+
+#ifndef HILBERT_TRANSFORM_HPP
+#define HILBERT_TRANSFORM_HPP
+
+#include "mbed.h"
+
+namespace Mikami
+{
+    template<int order> class Hilbert
+    {
+    private:
+        const float *const hm_; // pointer for filter coefficients
+        float xn_[order+1];     // buffer for inputs
+
+        Hilbert(const Hilbert&);
+        Hilbert& operator=(const Hilbert&);
+    public:
+        Hilbert(const float hk[]) : hm_(hk)
+        {
+            for (int k=0; k<=order; k++) xn_[k] = 0.0;
+        }
+        
+        // yI: in-phase signal
+        // yQ: quadrature signal
+        void Execute(float xin, float& yI, float& yQ)
+        {
+            yQ = 0.0;
+            xn_[0] = xin;
+
+            for (int k=0; k<=order/4; k++)
+                yQ = yQ + hm_[k]*(xn_[2*k] - xn_[order-2*k]);
+            yI = xn_[order/2];              // in-phase signal
+
+            for (int k=order; k>0; k--)
+                xn_[k] = xn_[k-1];          // move input signals        
+        }
+    };
+}
+#endif  // HILBERT_TRANSFORM_HPP
+

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/TwoPhaseGenerator.hpp	Tue Jul 15 09:11:35 2014 +0000
@@ -0,0 +1,42 @@
+//--------------------------------------------------------------
+// Two phase sin generator class
+// Copyright (c) 2014 MIKAMI, Naoki,  2014/06/23
+//--------------------------------------------------------------
+
+#ifndef TWO_PHASE_GENERATOR_HPP
+#define TWO_PHASE_GENERATOR_HPP
+
+#include "mbed.h"
+
+namespace Mikami
+{
+    class TwoPhaseGenerator
+    {
+    public:
+        // Constructor
+        TwoPhaseGenerator(float f0, float fs)
+            : a1_(cosf(6.283185f*f0/fs)),
+              b1_(sinf(6.283185f*f0/fs)),
+              xn1_(1.0f), yn1_(0.0f) {}
+
+        // -1.0f <= x1, x2 <= 1.0f
+        void Generate(float& xn, float& yn)
+        {
+            yn = a1_*yn1_ + b1_*xn1_;     // sin
+            xn = -b1_*yn1_ + a1_*xn1_;    // cos
+
+            float c1 = 1.5f - 0.5f*(xn*xn + yn*yn);
+
+            xn1_ = c1*xn;
+            yn1_ = c1*yn;
+        }
+
+    private:
+        const float a1_, b1_;
+        float xn1_, yn1_;
+
+        TwoPhaseGenerator(const TwoPhaseGenerator&);
+        TwoPhaseGenerator& operator=(const TwoPhaseGenerator&);
+    };
+}
+#endif  // TWO_PHASE_GENERATOR_HPP

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/coefsHilbert94.hpp	Tue Jul 15 09:11:35 2014 +0000
@@ -0,0 +1,20 @@
+//--------------------------------------------------------------
+//  Coefficients of FIR filter for Hilbert transform
+//  order = 94
+//--------------------------------------------------------------
+
+// lower edge band frequency (kHz) 0.100000
+// upper edge band frequency (kHz) 4.900000
+// deviation                       0.021787
+// deviation [dB]                  0.187207
+
+const int ORDER_ = 94;
+const float hm_[(ORDER_-2)/4+1] = {
+         -1.299277E-02f, -4.568317E-03f, -5.370440E-03f,
+         -6.267365E-03f, -7.268236E-03f, -8.387631E-03f,
+         -9.634522E-03f, -1.103786E-02f, -1.260725E-02f,
+         -1.437928E-02f, -1.639191E-02f, -1.868889E-02f,
+         -2.133888E-02f, -2.443648E-02f, -2.811453E-02f,
+         -3.256408E-02f, -3.808325E-02f, -4.515709E-02f,
+         -5.462150E-02f, -6.805616E-02f, -8.885052E-02f,
+         -1.258209E-01f, -2.113017E-01f, -6.363176E-01f};

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed.bld	Tue Jul 15 09:11:35 2014 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/mbed_official/code/mbed/builds/04dd9b1680ae
\ No newline at end of file