Merge pull request #16 from hansmi/master

AVR8: Add option to keep 3.3V regulator enabled.

LUFA/DoxygenPages/ChangeLog.txt

@@ -11,6 +11,7 @@
   *  - Library Applications:
   *   - Added new Bulk Vendor low level device demo
   *   - Added new libUSB host Python and NodeJS application examples for the class driver GenericHID demo (thanks to Laszlo Monda)
+  *   - Added new AVR8 USB option to keep 3.3V regulator enabled
   *
   *  <b>Changed:</b>
   *  - Library Applications:

LUFA/Drivers/USB/Core/AVR8/USBController_AVR8.c

@@ -112,6 +112,7 @@ void USB_Disable(void)
 	if (!(USB_Options & USB_OPT_MANUAL_PLL))
 	  USB_PLL_Off();
 
+	if (!(USB_Options & USB_OPT_REG_KEEP_ENABLED))
 	  USB_REG_Off();
 
 	#if defined(USB_SERIES_4_AVR) || defined(USB_SERIES_6_AVR) || defined(USB_SERIES_7_AVR)

LUFA/Drivers/USB/Core/AVR8/USBController_AVR8.h

@@ -133,6 +133,14 @@
 			 */
 			#define USB_OPT_REG_ENABLED                (0 << 1)
 
+			/** Option mask for \ref USB_Init() to keep regulator enabled at all times. Indicates that \ref USB_Disable()
+			 *  should not disable the regulator as it would otherwise. Has no effect if regulator is disabled using
+			 *  \ref USB_OPT_REG_DISABLED.
+			 *
+			 *  \note See USB AVR data sheet for more information on the internal pad regulator.
+			 */
+			#define USB_OPT_REG_KEEP_ENABLED           (1 << 3)
+
 			/** Manual PLL control option mask for \ref USB_Init(). This indicates to the library that the user application
 			 *  will take full responsibility for controlling the AVR's PLL (used to generate the high frequency clock
 			 *  that the USB controller requires) and ensuring that it is locked at the correct frequency for USB operations.