Diff: main.cpp

Revision:

0:000c6506ff90

Child:

1:4fc93890f58e

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Mon Jul 23 17:05:39 2018 +0000
@@ -0,0 +1,79 @@
+/*
+   Nucleo F767 DCO
+   2018.07.22
+
+*/
+#include "mbed.h"
+
+#include "wavetable_12bit_16k.h"
+#define COUNT_OF_ENTRIES  (16384)
+
+#define PIN_CHECK   (1)
+#define UART_TRACE  (0)
+#define TITLE_STR1  ("Nucleo F767 DCO")
+#define TITLE_STR2  ("20180724")
+
+// Pin Assign
+AnalogOut Dac1(PA_4);
+AnalogOut Dac2(PA_5);
+
+#if (PIN_CHECK)
+DigitalOut CheckPin(D4);
+#endif
+
+// Parameter
+double drate = 1000.0;          // initial output rate (Hz)
+const double refclk = 418000.0;  // Hz
+
+// Interruput
+Ticker ticker;
+
+// DDS
+volatile uint32_t phaccu;
+volatile uint32_t tword_m;
+
+//-------------------------------------------------------------------------------------------------
+// Interrupt Service Routine
+//
+
+// param
+//   val: 0 .. 4095
+void InternalDacWrite(uint16_t val)
+{
+    // avoid distortion of built-in DAC
+    uint16_t v = ((val + 1024) << 3);
+    
+    Dac2.write_u16(v);
+}
+
+void update()
+{
+#if (PIN_CHECK)
+    CheckPin.write(1);
+#endif
+
+    phaccu = phaccu + tword_m;
+    uint16_t idx = phaccu >> 18;  // use upper 14 bits
+    
+    InternalDacWrite(sin_12bit_16k[idx]);
+
+#if (PIN_CHECK)
+    CheckPin.write(0);
+#endif
+}
+
+//-------------------------------------------------------------------------------------------------
+// Main routine
+//
+
+int main()
+{
+    tword_m = pow(2.0, 32) * drate / refclk;  // calculate DDS tuning word;
+    
+    float interruptPeriodUs = 1000000.0 / refclk; 
+    ticker.attach_us(&update, interruptPeriodUs);
+    
+    while (1) {
+    }
+}
+