Diff: main.cpp

Revision:

0:3f57c7540719

Child:

1:5016cbf30cd0

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Mon Oct 20 23:24:25 2014 +0000
@@ -0,0 +1,61 @@
+//--------------------------------------------------------------
+// IIR フィルタ，直接形，double 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_ = 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_(DAC_MCP4922::DAC_A); // for DA
+
+int main()
+{
+    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
+    }
+}
+