lowlevel.h

userial is an Free project building an USB to I2C/SPI/GPIO bridge, using the Atmel AT90USB647 chip.

			 */
			#define USB_Detach()                    MACROS{ UDCON  |=  (1 << DETACH);  }MACROE

			/** Attaches the device to the USB bus. This announces the device's presence to any attached
			 *  USB host, starting the enumeration process. If no host is present, attaching the device
			 *  will allow for enumeration once a host is connected to the device.
			 *
			 *  This is inexplicably also required for proper operation while in host mode, to enable the
			 *  attachment of a device to the host. This is despite the bit being located in the device-mode
			 *  register and despite the datasheet making no mention of its requirement in host mode.
			 */
			#define USB_Attach()                    MACROS{ UDCON  &= ~(1 << DETACH);  }MACROE
			
			#if !defined(USB_STREAM_TIMEOUT_MS) || defined(__DOXYGEN__)
				/** Constant for the maximum software timeout period of the USB data stream transfer functions
				 *  (both control and standard) when in either device or host mode. If the next packet of a stream
				 *  is not received or acknowedged within this time period, the stream function will fail.
				 *
				 *  This value may be overridden in the user project makefile as the value of the 
				 *  USB_STREAM_TIMEOUT_MS token, and passed to the compiler using the -D switch.
				 */
				#define USB_STREAM_TIMEOUT_MS       100
			#endif

		/* Function Prototypes: */
			/** Main function to initialize and start the USB interface. Once active, the USB interface will
			 *  allow for device connection to a host when in device mode, or for device enumeration while in
			 *  host mode.
			 *
			 *  As the USB library relies on USB interrupts for some of its functionality, this routine will
			 *  enable global interrupts.
			 *
			 *  Calling this function when the USB interface is already initialized will cause a complete USB
			 *  interface reset and re-enumeration.
			 *
			 *  \param Mode     This is a mask indicating what mode the USB interface is to be initialized to.
			 *                  Valid mode masks are USB_MODE_DEVICE, USB_MODE_HOST or USB_MODE_UID.
			 *
			 *  \param Options  Mask indicating the options which should be used when initializing the USB
			 *                  interface to control the USB interface's behaviour. This should be comprised of
			 *                  a USB_OPT_REG_* mask to control the regulator, a USB_OPT_*_PLL mask to control the
			 *                  PLL, and a USB_DEVICE_OPT_* mask (when the device mode is enabled) to set the device
			 *                  mode speed.
			 *
			 *  \note To reduce the FLASH requirements of the library if only device or host mode is required, 
			 *        this can be statically set via defining the token USB_DEVICE_ONLY for device mode or 
			 *        USB_HOST_ONLY for host mode in the use project makefile, passing the token to the compiler 
			 *        via the -D switch. If the mode is statically set, this parameter does not exist in the
			 *        function prototype.
			 *
			 *  \note To reduce the FLASH requirements of the library if only fixed settings are are required,
			 *        the options may be set statically in the same manner as the mode (see the Mode parameter of 
			 *        this function). To statically set the USB options, pass in the USE_STATIC_OPTIONS token,
			 *        defined to the appropriate options masks. When the options are statically set, this
			 *        parameter does not exist in the function prototype.
			 *        
			 *  \note The mode parameter does not exist on devices where only one mode is possible, such as USB 
			 *        AVR models which only implement the USB device mode in hardware.
			 *
			 *  \see Device.h for the USB_DEVICE_OPT_* masks.
			 */
			void USB_Init(
			               #if defined(USB_CAN_BE_BOTH) || defined(__DOXYGEN__)
			               const uint8_t Mode
						   #endif

			               #if (defined(USB_CAN_BE_BOTH) && !defined(USE_STATIC_OPTIONS)) || defined(__DOXYGEN__)
			               ,
						   #elif (!defined(USB_CAN_BE_BOTH) && defined(USE_STATIC_OPTIONS))
						   void
			               #endif
						   
			               #if !defined(USE_STATIC_OPTIONS) || defined(__DOXYGEN__)
			               const uint8_t Options
			               #endif
			               );
			
			/** Shuts down the USB interface. This turns off the USB interface after deallocating all USB FIFO
			 *  memory, endpoints and pipes. When turned off, no USB functionality can be used until the interface
			 *  is restarted with the USB_Init() function.
			 */
			void USB_ShutDown(void);

			/** Resets the interface, when already initialized. This will re-enumerate the device if already connected
			 *  to a host, or re-enumerate an already attached device when in host mode.
			 */
			void USB_ResetInterface(void);

		/* Enums: */
			/** Enum for error codes relating to the powering on of the USB interface. These error codes are
			 *  used in the ErrorCode parameter value of the USB_PowerOnFail event.
			 */
			enum USB_PowerOnErrorCodes_t
			{
				POWERON_ERROR_NoUSBModeSpecified       = 0, /**< Indicates that USB_Init() was called with an
			                                                 *   invalid or missing Mode parameter.
			                                                 */
			};

		/* Global Variables: */
			#if (!defined(USB_HOST_ONLY) && !defined(USB_DEVICE_ONLY)) || defined(__DOXYGEN__)
				/** Indicates the mode that the USB interface is currently initialized to. This value will be
				 *  one of the USB_MODE_* masks defined elsewhere in this module.
				 *
				 *  \note This variable should be treated as read-only in the user application, and never manually
				 *        changed in value.
				 */
				extern volatile uint8_t USB_CurrentMode;
			#endif
			
			#if !defined(USE_STATIC_OPTIONS) || defined(__DOXYGEN__)
				extern volatile uint8_t USB_Options;
				/** Indicates the current USB options that the USB interface was initialized with when USB_Init()
				 *  was called. This value will be one of the USB_MODE_* masks defined elsewhere in this module.
				 *
				 *  \note This variable should be treated as read-only in the user application, and never manually
				 *        changed in value.
				 */
			#endif

		/* Throwable Events: */
			/** This module raises the USB_Disconnect event if the USB interface is reset (such as during a mode
			 *  change while in UID mode) while the USB interface is connected to a device when in host mode, or
			 *  a host while in device mode.
			 *
			 *  \see Events.h for more information on this event.
			 */
			RAISES_EVENT(USB_Disconnect);
			
			#if defined(USB_CAN_BE_BOTH) || defined(__DOXYGEN__)
				/** This module raises the Power On Failure event when an error occurs while initializing the USB
				 *  interface.
				 *
				 *  \see Events.h for more information on this event.
				 */
				RAISES_EVENT(USB_PowerOnFail);
			#endif
			
	/* Private Interface - For use in library only: */
	#if !defined(__DOXYGEN__)
		/* Macros: */
			#define USB_PLL_On()               MACROS{ PLLCSR   =  USB_PLL_PSC; PLLCSR |= (1 << PLLE); }MACROE
			#define USB_PLL_Off()              MACROS{ PLLCSR   =  0;                           }MACROE
			#define USB_PLL_IsReady()                ((PLLCSR  &   (1 << PLOCK)) ? true : false)

			#if defined(USB_FULL_CONTROLLER) || defined(USB_MODIFIED_FULL_CONTROLLER)		
				#define USB_REG_On()           MACROS{ UHWCON  |=  (1 << UVREGE);               }MACROE
				#define USB_REG_Off()          MACROS{ UHWCON  &= ~(1 << UVREGE);               }MACROE
			#else
				#define USB_REG_On()           MACROS{ REGCR   &= ~(1 << REGDIS);               }MACROE
				#define USB_REG_Off()          MACROS{ REGCR   |=  (1 << REGDIS);               }MACROE			
			#endif
			
			#define USB_OTGPAD_On()            MACROS{ USBCON  |=  (1 << OTGPADE);              }MACROE
			#define USB_OTGPAD_Off()           MACROS{ USBCON  &= ~(1 << OTGPADE);              }MACROE

			#define USB_CLK_Freeze()           MACROS{ USBCON  |=  (1 << FRZCLK);               }MACROE
			#define USB_CLK_Unfreeze()         MACROS{ USBCON  &= ~(1 << FRZCLK);               }MACROE

			#define USB_Interface_Enable()     MACROS{ USBCON  |=  (1 << USBE);                 }MACROE
			#define USB_Interface_Disable()    MACROS{ USBCON  &= ~(1 << USBE);                 }MACROE
			#define USB_Interface_Reset()      MACROS{ uint8_t Temp = USBCON; USBCON = (Temp & ~(1 << USBE)); \
			                                           USBCON = (Temp | (1 << USBE));           }MACROE
	
		/* Inline Functions: */		
			static inline uint8_t USB_GetUSBModeFromUID(void) ATTR_WARN_UNUSED_RESULT;
			static inline uint8_t USB_GetUSBModeFromUID(void)
			{
				#if (defined(__AVR_AT90USB1287__) || defined(__AVR_AT90USB647__))
				if (USBSTA & (1 << ID))
				  return USB_MODE_DEVICE;
				else
				  return USB_MODE_HOST;
				#else
				return USB_MODE_DEVICE;
				#endif
			}
	#endif
	
	/* Disable C linkage for C++ Compilers: */
		#if defined(__cplusplus)
			}
		#endif
			
#endif