Diff: main.cpp

Revision:

0:606470358828

diff -r 000000000000 -r 606470358828 main.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Sat Nov 15 09:52:03 2014 +0000
@@ -0,0 +1,58 @@
+//--------------------------------------------------------------
+// Adaptive line enhancer (ALE) by FIR filter using
+// LMS algorithm
+//      Analog Input : A0
+//      Analog Output: MCP4922 using SPI
+// 2014/11/15, Copyright (c) 2014 MIKAMI, Naoki
+//--------------------------------------------------------------
+
+#include "mbed.h"
+
+#include "ADC_Base.hpp"         // for ADC not using interrupt
+#include "DAC_MCP4922.hpp"      // for DAC MCP4922
+
+using namespace Mikami;
+
+const int FS_ = 16000;  // Sampling frequency: 16 kHz
+ADC_Base adc_(A0, FS_); // for AD
+DAC_MCP4922 myDac_;     // for DA
+DigitalIn sw_(D2, PullDown);
+
+int main()
+{
+    myDac_.ScfClockTim3(500000);    // cutoff frequency: 5 kHz
+
+    const int ORDER = 100;      // Order of FIR filter
+    const int DELAY = 5;        // Number of delay to reduce correlation
+    const int N_ALL = ORDER + DELAY + 1;
+    const float MU = 1.0e-4f;   // Step size parameter
+    
+    float xn[N_ALL], hm[ORDER+1];
+    
+    for (int n=0; n<N_ALL; n++) xn[n] = 0;
+    for (int n=0; n<=ORDER; n++) hm[n] = 0;
+    
+    while (true)
+    {
+        xn[0] = adc_.Read();    // Read from A0
+        //-----------------------------------------------
+
+        // Execute FIR filter
+        float yn = 0;
+        for (int k=0; k<=ORDER; k++)
+            yn = yn + hm[k]*xn[k+DELAY];
+
+        // Update ceefficients
+        float err_mu = (xn[0] - yn)*MU;
+        for (int k=0; k<=ORDER; k++)
+            hm[k] = hm[k] + err_mu*xn[k+DELAY];
+        
+        // Move input signal in delays
+        for (int k=N_ALL-1; k>0; k--)
+            xn[k] = xn[k-1];    // move input signals
+
+        if (sw_.read() == 0) yn = xn[0];   // no ALE
+        //-----------------------------------------------
+        myDac_.Write(yn);       // Write to DAC
+    }
+}