From bd7c712d5990548aff35accf2f996c59850924ac Mon Sep 17 00:00:00 2001
From: Elena of Valhalla'' Grandi <valhalla@trueelena.org>
Date: Wed, 14 Aug 2013 11:56:37 +0200
Subject: Support for common cathode RGB LEDs

---
 Colours.cpp                            | 22 +++++++++++++++++++---
 Colours.h                              |  3 +++
 examples/hue_rotation/hue_rotation.ino |  3 +++
 3 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/Colours.cpp b/Colours.cpp
index bb77e85..50b782d 100644
--- a/Colours.cpp
+++ b/Colours.cpp
@@ -6,6 +6,16 @@
 #include "Colours.h"
 
 Colours::Colours(int rPin,int gPin,int bPin) {
+    _initPINs(rPin,gPin,bPin);
+    _invert = false;
+}
+
+Colours::Colours(int rPin,int gPin,int bPin,bool invert) {
+    _initPINs(rPin,gPin,bPin);
+    _invert = invert;
+}
+
+void Colours::_initPINs(int rPin,int gPin,int bPin) {
     _rPin = rPin;
     _gPin = gPin;
     _bPin = bPin;
@@ -15,9 +25,15 @@ Colours::Colours(int rPin,int gPin,int bPin) {
 }
 
 void Colours::writeRGB(unsigned char r,unsigned char g,unsigned char b) {
-    analogWrite(_rPin, r);
-    analogWrite(_gPin, g);
-    analogWrite(_bPin, b);
+    if (_invert) {
+        analogWrite(_rPin, 255-r);
+        analogWrite(_gPin, 255-g);
+        analogWrite(_bPin, 255-b);
+    } else {
+        analogWrite(_rPin, r);
+        analogWrite(_gPin, g);
+        analogWrite(_bPin, b);
+    }
 }
 
 void Colours::writeHSV(unsigned int h,unsigned char s,unsigned char v) {
diff --git a/Colours.h b/Colours.h
index cd08bfc..c91b30a 100644
--- a/Colours.h
+++ b/Colours.h
@@ -10,10 +10,13 @@
 class Colours {
     public:
         Colours(int rPin,int gPin,int bPin);
+        Colours(int rPin,int gPin,int bPin,bool invert);
         void writeRGB(unsigned char r,unsigned char g,unsigned char b);
         void writeHSV(unsigned int h,unsigned char s,unsigned char v);
     private:
         int _rPin,_gPin,_bPin;
+        bool _invert;
+        void _initPINs(int rPin,int gPin,int bPin);
 };
 
 #endif
diff --git a/examples/hue_rotation/hue_rotation.ino b/examples/hue_rotation/hue_rotation.ino
index 2151618..6e57069 100644
--- a/examples/hue_rotation/hue_rotation.ino
+++ b/examples/hue_rotation/hue_rotation.ino
@@ -1,6 +1,9 @@
 #include <Colours.h>
 
 Colours colours(6,5,3);
+// For common cathode RGB LEDs comment the line above and uncomment 
+// the one below.
+//Colours colours(6,5,3,true);
 
 void setup() {
 }
-- 
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