Diff: main.cpp

Revision:

0:8edfedfcdd26

Child:

2:799a843be414

diff -r 000000000000 -r 8edfedfcdd26 main.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Tue Oct 21 12:52:45 2014 +0000
@@ -0,0 +1,43 @@
+//--------------------------------------------------------------
+// Sin generator using IIR filter
+//      Analog Output: MCP4922 using SPI
+// 2014/10/21, Copyright (c) 2014 MIKAMI, Naoki
+//--------------------------------------------------------------
+
+#include "mbed.h"
+
+#include "ADC_Base.hpp"         // for ADC not using interrupt
+#include "DAC_MCP4922.hpp"      // for DAC MCP4922
+#include "ScfClockTim3.hpp"     // for clock supplied to SCF
+
+using namespace Mikami;
+
+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()
+{
+    const float PI2 = 6.283185f;
+    const float F0 = 440.0f;
+    const float A1 = 2.0f*cosf(PI2*F0/(float)FS_);
+    const float B1 = 0.8f*sinf(PI2*F0/(float)FS_);
+
+    ScfClockTim3(500000);       // cutoff frequency: 5 kHz
+
+    float yn1 = B1;
+    float yn2 = 0;
+    
+    while (true)
+    {
+        float xn = adc_.Read();     // Dummy read for synchronization to Fs
+        //-----------------------------------------------
+        
+        float yn = A1*yn1 - yn2;    // y[n] = a1*y[n-1] - y[n-2]
+        yn2 = yn1;                  // y[n-2] <= y[n-1]
+        yn1 = yn;                   // y[n-1] <= y[n]
+
+        //-----------------------------------------------
+        myDac_.Write(yn);           // Write to DAC
+    }
+}