From 016ad2398a5496364b0392e94c3269670700d015 Mon Sep 17 00:00:00 2001
From: Stephen Olesen <slepp@slepp.ca>
Date: Wed, 1 Jul 2015 15:01:55 -0600
Subject: [PATCH] Added a define to use pin 3 for PWM, instead of the new
 default pin 11.

---
 DDS.cpp | 6 ++++++
 DDS.h   | 5 +++++
 2 files changed, 11 insertions(+)

diff --git a/DDS.cpp b/DDS.cpp
index da39970..27129aa 100644
--- a/DDS.cpp
+++ b/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.
diff --git a/DDS.h b/DDS.h
index a1d54f5..edab90a 100644
--- a/DDS.h
+++ b/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