Extend RGB LED support, adding Printer Events

Marlin/example_configurations/K8400/Dual-head/Configuration.h

@@ -1514,7 +1514,23 @@
 //define BlinkM/CyzRgb Support
 //#define BLINKM
 
-// Support for an RGB LED using 3 separate pins with optional PWM
+/**
+ * RGB LED / LED Strip Control
+ *
+ * Enable support for an RGB LED connected to 5V digital pins, or
+ * an RGB Strip connected to MOSFETs controlled by digital pins.
+ *
+ * Adds the M150 command to set the LED (or LED strip) color. 
+ * If pins are PWM capable (e.g., 4, 5, 6, 11) then a range of
+ * luminance values can be set from 0 to 255.
+ *
+ * *** CAUTION ***
+ *  LED Strips require a MOFSET Chip between PWM lines and LEDs,
+ *  as the Arduino cannot handle the current the LEDs will require.
+ *  Failure to follow this precaution can destroy your Arduino!
+ * *** CAUTION ***
+ *
+ */
 //#define RGB_LED
 #if ENABLED(RGB_LED)
   #define RGB_LED_R_PIN 34
@@ -1522,6 +1538,21 @@
   #define RGB_LED_B_PIN 35
 #endif
 
+/**
+ * Printer Event LEDs
+ *
+ * During printing, the LEDs will reflect the printer status:
+ *
+ *  - Gradually change from blue to violet as the heated bed gets to target temp
+ *  - Gradually change from violet to red as the hotend gets to temperature
+ *  - Change to white to illuminate work surface
+ *  - Change to green once print has finished
+ *  - Turn off after the print has finished and the user has pushed a button
+ */
+#if ENABLED(BLINKM) || ENABLED(RGB_LED)
+  #define PRINTER_EVENT_LEDS
+#endif
+
 /*********************************************************************\
 * R/C SERVO support
 * Sponsored by TrinityLabs, Reworked by codexmas