Added a define to use pin 3 for PWM, instead of the new default pin 11.

DDS.cpp

@@ -10,8 +10,14 @@ void DDS::start() {
   // First, the timer for the PWM output
   // Setup the timer to use OC2B (pin 3) in fast PWM mode with a configurable top
   // Run it without the prescaler
+#ifdef DDS_PWM_PIN_3
   TCCR2A = (TCCR2A | _BV(COM2B1)) & ~(_BV(COM2B0) | _BV(COM2A1) | _BV(COM2A0)) |
          _BV(WGM21) | _BV(WGM20);
+#else
+  // Alternatively, use pin 11
+  TCCR2A = (TCCR2A | _BV(COM2A1)) & ~(_BV(COM2A0) | _BV(COM2B1) | _BV(COM2B0)) |
+       _BV(WGM21) | _BV(WGM20);
+#endif
   TCCR2B = (TCCR2B & ~(_BV(CS22) | _BV(CS21))) | _BV(CS20) | _BV(WGM22);
 
   // Set the top limit, which will be our duty cycle accuracy.

DDS.h

@@ -3,6 +3,11 @@
 
 #include <avr/pgmspace.h>
 
+// Use pin 3 for PWM? If not defined, use pin 11
+// #define DDS_PWM_PIN_3
+
+// Use a short (16 bit) accumulator. Phase accuracy is reduced, but speed
+// is increased, along with a reduction in memory use.
 #define SHORT_ACCUMULATOR
 
 #ifdef SHORT_ACCUMULATOR