Revision 0:b8bffbcb85fd, committed 2014-11-10

Comitter:

MikamiUitOpen

Date:

Mon Nov 10 02:45:18 2014 +0000

Child:

1:24c33c8719b2

Commit message:

1

Changed in this revision

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/UIT_ACM1602NI.lib	Mon Nov 10 02:45:18 2014 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/MikamiUitOpen/code/UIT_ACM1602NI/#7c6b2df4e60b

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/UIT_ADDA.lib	Mon Nov 10 02:45:18 2014 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/MikamiUitOpen/code/UIT_ADDA/#651809e96a2d

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/WindowingDesignLpfHpf/WindowingDesignLH.cpp	Mon Nov 10 02:45:18 2014 +0000
@@ -0,0 +1,92 @@
+//------------------------------------------------------------------------------
+//  Design of FIR filter of LPF and HPF using window method
+//
+//  2014/11/09, Copyright (c) 2014 MIKAMI, Naoki
+//------------------------------------------------------------------------------
+
+#include "WindowingDesignLH.hpp"
+
+namespace Mikami
+{
+    WindowingDesign::WindowingDesign(int order, float fs)
+            : FS_(fs), PI_FS_(3.1415926536f/fs)
+    {
+        order_ = order;
+        if ((order % 2) != 0)
+        {
+            fprintf(stderr, "order must be even.");
+            return;
+        }
+        hm_ = new float[order/2+1];
+        wn_ = new float[order/2+1];    
+        
+        HammWindow();
+    }
+        
+    void WindowingDesign::Design(int order, Type pb, float fc,
+                                 float hk[])
+    {       
+        if (pb == LPF) fC_ = fc;
+        if (pb == HPF) fC_ = 0.5f*FS_ - fc;
+    
+        if (order != order_)
+        {
+            order_ = order_;
+            if (hm_ != NULL) delete[] hm_;
+            hm_ = new float[order/2+1];
+            if (wn_ != NULL) delete[] wn_;
+            wn_ = new float[order/2+1];
+            HammWindow();
+        }
+
+        // Calculate coefficients for LPF
+        LpfCoefficients();
+        // If HPF, transform coefficients
+        if (pb != LPF) ToHpf();
+        
+        for (int k=0; k<=order/2; k++)
+            hk[k] = hm_[order/2-k];
+
+        // For compensation of gain
+        float sum = hk[order_/2];
+        if (pb == LPF)
+            for (int k=0; k<order_/2; k++)
+                sum = sum + 2.0f*hk[k];
+        if (pb == HPF)
+        {
+            float sign = -1.0;
+            for (int k=order_/2-1; k>=0; k--)
+            {
+                sum = sum + sign*2.0f*hk[k];
+                sign = -sign;
+            }
+        }
+        for (int k=0; k<=order_/2; k++)
+            hk[k] = hk[k]/sum;
+    }
+
+    // Calculation of coefficients for LPF
+    void WindowingDesign::LpfCoefficients()
+    {
+        float w = 2.0f*PI_FS_*fC_;
+        hm_[0] = 2.0f*fC_/FS_;
+        for (int k=1; k<=order_/2; k++)
+            hm_[k] = (sinf(k*w)/(PI_*k))*wn_[k];  
+    }
+    
+    // Transform LPF to HPF
+    void WindowingDesign::ToHpf()
+    {
+        for (int k=1; k<=order_/2; k+=2)
+            hm_[k] = -hm_[k];
+    }    
+
+    // Hamming window
+    void WindowingDesign::HammWindow()
+    {
+        float pi2OvM = 2.0f*PI_/(float)(order_ + 1);
+        for (int n=0; n<=order_/2; n++)
+            wn_[n] = 0.54f + 0.46f*cosf(pi2OvM*n);
+    }
+}
+

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/WindowingDesignLpfHpf/WindowingDesignLH.hpp	Mon Nov 10 02:45:18 2014 +0000
@@ -0,0 +1,52 @@
+//------------------------------------------------------------------------------
+//  Design of FIR filter of LPF and HPF using window method -- Header
+//
+//  2014/11/09, Copyright (c) 2014 MIKAMI, Naoki
+//------------------------------------------------------------------------------
+
+#ifndef HAMMING_WINDOWING_DESIGN_HPP
+#define HAMMING_WINDOWING_DESIGN_HPP
+
+#include "mbed.h"
+
+namespace Mikami
+{
+    class WindowingDesign
+    {
+    public:
+        struct Coefs { float a1, a2, b1; };
+        enum Type { LPF, HPF };
+
+        // Constructor
+        WindowingDesign(int order, float fs);
+
+        //Destructor
+        ~WindowingDesign()
+        {
+            delete[] hm_;
+            delete[] wn_;
+        }
+
+        // Execution of design
+        void Design(int order, Type pb, float fc, float hk[]);
+
+    private:
+        static const float PI_ = 3.1415926536f;
+        const float FS_;    // Sampling frequency
+        const float PI_FS_;
+        
+        float *hm_;     // For coefficients
+        float *wn_;     // For Windwo
+                
+        int order_;     // Order
+        float fC_;      // Cutoff frequency
+        
+        // Calculation of coefficients for LPF
+        void LpfCoefficients();
+        // Transform LPF to HPF
+        void ToHpf();
+        // Hamming window
+        void HammWindow();
+    };
+}
+#endif  // HAMMING_WINDOWING_DESIGN_HPP

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Mon Nov 10 02:45:18 2014 +0000
@@ -0,0 +1,125 @@
+//------------------------------------------------------------------
+// Cutoff frequency variable LPF and HPF by FIR 160th-order filter
+//      A0: Signal to be filtered
+//      A2: Value which controls cutoff frequency
+//
+// 2014/11/10, 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
+#include "ACM1602NI.hpp"        // for LCD display
+
+#include "WindowingDesignLH.hpp" // for design of IIR filter
+
+using namespace Mikami;
+
+const int FS_ = 16000;          // Sampling frequency: 16 kHz
+ADC_Intr myAdc_(A0, FS_, A1, A2);
+DAC_MCP4922 myDac_;
+
+const int ORDER_ = 160;
+float hm_[ORDER_/2+1];
+float xn_[ORDER_+1];
+
+DigitalIn sw1_(D2, PullDown);   // 0: disable filter
+                                // 1: enable filter
+DigitalIn sw2_(D3, PullDown);   // 0: LPF
+                                // 1: HPF
+WindowingDesign design_(ORDER_, FS_);
+DigitalOut dOut_(D7);
+
+uint16_t a2_ = 0;   // Inputted data from A2 pin
+
+// Interrupt service routine for ADC
+void AdcIsr()
+{   
+    dOut_.write(1);
+    xn_[0] = myAdc_.Read();   // Read from A0
+
+    myAdc_.Select3rdChannel();  // Select A2   
+    myAdc_.SoftStart();         // ADC start for A2 input
+
+    //-----------------------------------------
+    // Execute FIR filter
+        float yn = hm_[ORDER_/2]*xn_[ORDER_/2];
+        for (int k=0; k<ORDER_/2; k++)
+            yn = yn + hm_[k]*(xn_[k] + xn_[ORDER_-k]);
+
+        for (int k=ORDER_; k>0; k--)
+            xn_[k] = xn_[k-1];  // move input signals
+    //-----------------------------------------
+
+    if (sw1_ == 0) myDac_.Write(xn_[0]);    // Using no filter
+    else           myDac_.Write(yn);        // Using filter
+
+    // Read value which controls cutoff frequency
+    a2_ = myAdc_.ReadWait_u16();
+
+    myAdc_.Select1stChannel();      // Select A0
+    myAdc_.ClearPending_EnableIRQ();// Clear pending interrupt
+                                    // and enable ADC_IRQn
+    dOut_.write(0);
+}
+
+int main()
+{
+    ScfClockTim3(670000);       // cutoff frequency: 6.7 kHz
+
+    WindowingDesign lpfDsgn(ORDER_, FS_);
+    Acm1602Ni lcd;  // objetc for display using LCD
+
+    // Clear buffer in FIR filter
+    for (int n=0; n<=ORDER_; n++)
+        xn_[n] = 0;
+    myAdc_.SetIntrVec(AdcIsr);  // Assign ISR for ADC interrupt
+
+    float fc1 = 0;
+    WindowingDesign::Type pb = WindowingDesign::LPF;
+    while (true)
+    {
+        // fc: cutoff frequency, 100 -- 2000 Hz
+        float fc = 1900.0f*(a2_/4095.6f) + 100.0f;
+
+        if (sw1_ == 0)
+        {
+            printf("Through\r\n");
+            lcd.ClearLine(1);
+            lcd.WriteStringXY("Through         ", 0, 0);
+            wait(0.2f);
+            lcd.ClearLine(0);           
+            fc1 = 0;
+        }
+        else
+        {
+            if (fabs(fc - fc1) > 10.0f)
+            {
+                printf("fc = %4d\r\n", int(fc+0.5f));
+                char str[18];
+                sprintf(str, "fc = %4d Hz", int(fc+0.5f));
+                lcd.WriteStringXY(str, 0, 0);
+                if (sw2_ == 0)
+                {
+                    pb = WindowingDesign::LPF;
+                    printf("LPF\r\n");
+                    lcd.WriteStringXY("LPF", 0, 1);
+                }
+                else
+                {
+                    pb = WindowingDesign::HPF;
+                    printf("HPF\r\n");
+                    lcd.WriteStringXY("HPF", 0, 1);
+                }
+                fc1 = fc;
+
+                // Design new coefficients based on new fc
+                design_.Design(ORDER_, pb, fc1, hm_);
+            }
+        }
+        wait(0.1f);
+    }
+}
+

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed.bld	Mon Nov 10 02:45:18 2014 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/mbed_official/code/mbed/builds/031413cf7a89
\ No newline at end of file