USB Interface Management
[USB - LUFA/Drivers/USB/USB.h]

Defines

#define USB_MODE_NONE   0
#define USB_MODE_DEVICE   1
#define USB_MODE_HOST   2
#define USB_MODE_UID   3
#define USB_OPT_REG_DISABLED   (1 << 1)
#define USB_OPT_REG_ENABLED   (0 << 1)
#define USB_OPT_MANUAL_PLL   (1 << 2)
#define USB_OPT_AUTO_PLL   (0 << 2)
#define EP_TYPE_CONTROL   0x00
#define EP_TYPE_ISOCHRONOUS   0x01
#define EP_TYPE_BULK   0x02
#define EP_TYPE_INTERRUPT   0x03
#define USB_VBUS_GetStatus()   ((USBSTA & (1 << VBUS)) ? true : false)
#define USB_Detach()   MACROS{ UDCON |= (1 << DETACH); }MACROE
#define USB_Attach()   MACROS{ UDCON &= ~(1 << DETACH); }MACROE
#define USB_STREAM_TIMEOUT_MS   100

Enumerations

enum  USB_InitErrorCodes_t { USB_INITERROR_NoUSBModeSpecified = 0 }

Functions

void USB_USBTask (void)
void USB_Init (const uint8_t Mode, const uint8_t Options)
void USB_ShutDown (void)
void USB_ResetInterface (void)

Variables

volatile bool USB_IsInitialized
USB_Request_Header_t USB_ControlRequest
volatile uint8_t USB_CurrentMode
volatile uint8_t USB_Options

Detailed Description

Functions, macros, variables, enums and types related to the setup and management of the USB interface.


Define Documentation

#define EP_TYPE_BULK   0x02

Mask for a BULK type endpoint or pipe.

Note:
See Endpoint Management and Pipe Management for endpoint/pipe functions.
#define EP_TYPE_CONTROL   0x00

Mask for a CONTROL type endpoint or pipe.

Note:
See Endpoint Management and Pipe Management for endpoint/pipe functions.
#define EP_TYPE_INTERRUPT   0x03

Mask for an INTERRUPT type endpoint or pipe.

Note:
See Endpoint Management and Pipe Management for endpoint/pipe functions.
#define EP_TYPE_ISOCHRONOUS   0x01

Mask for an ISOCHRONOUS type endpoint or pipe.

Note:
See Endpoint Management and Pipe Management for endpoint/pipe functions.
 
#define USB_Attach (  )     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_Detach (  )     MACROS{ UDCON |= (1 << DETACH); }MACROE

Detaches the device from the USB bus. This has the effect of removing the device from any attached host, ceasing USB communications. If no host is present, this prevents any host from enumerating the device once attached until USB_Attach() is called.

#define USB_MODE_DEVICE   1

Mode mask for the USB_CurrentMode global and the USB_Init() function. This indicates that the USB interface is or should be initialized in the USB device mode.

#define USB_MODE_HOST   2

Mode mask for the USB_CurrentMode global and the USB_Init() function. This indicates that the USB interface is or should be initialized in the USB host mode.

Note:
This token is not available on AVR models which do not support host mode.
#define USB_MODE_NONE   0

Mode mask for the USB_CurrentMode global. This indicates that the USB interface is currently not initialized into any mode.

#define USB_MODE_UID   3

Mode mask for the the USB_Init() function. This indicates that the USB interface should be initialized into whatever mode the UID pin of the USB AVR indicates, and that the device should swap over its mode when the level of the UID pin changes during operation.

Note:
This token is not available on AVR models which do not support both host and device modes.
#define USB_OPT_AUTO_PLL   (0 << 2)

Automatic PLL control option mask for USB_Init(). This indicates to the library that the library should 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.

#define USB_OPT_MANUAL_PLL   (1 << 2)

Manual PLL control option mask for 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.

#define USB_OPT_REG_DISABLED   (1 << 1)

Regulator disable option mask for USB_Init(). This indicates that the internal 3.3V USB data pad regulator should be enabled to regulate the data pin voltages to within the USB standard.

Note:
See USB AVR data sheet for more information on the internal pad regulator.
#define USB_OPT_REG_ENABLED   (0 << 1)

Regulator enable option mask for USB_Init(). This indicates that the internal 3.3V USB data pad regulator should be disabled and the AVR's VCC level used for the data pads.

Note:
See USB AVR data sheet for more information on the internal pad regulator.
#define USB_STREAM_TIMEOUT_MS   100

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 acknowledged 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_VBUS_GetStatus (  )     ((USBSTA & (1 << VBUS)) ? true : false)

Returns boolean true if the VBUS line is currently high (i.e. the USB host is supplying power), otherwise returns false.

Note:
This token is not available on some AVR models which do not support hardware VBUS monitoring.

Enumeration Type Documentation

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 EVENT_USB_InitFailure() event.

Enumerator:
USB_INITERROR_NoUSBModeSpecified 

Indicates that USB_Init() was called with an invalid or missing Mode parameter.


Function Documentation

void USB_Init ( const uint8_t  Mode,
const uint8_t  Options 
)

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.

Parameters:
[in] 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.
[in] 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.
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.
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 also:
Device.h for the USB_DEVICE_OPT_* masks.
void USB_ResetInterface ( 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_ShutDown ( void   ) 

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_USBTask ( void   ) 

This is the main USB management task. The USB driver requires that this task be executed continuously when the USB system is active (device attached in host mode, or attached to a host in device mode) in order to manage USB communications. This task may be executed inside an RTOS, fast timer ISR or the main user application loop.

The USB task must be serviced within 30ms while in device mode, or within 1ms while in host mode. The task may be serviced at all times, or (for minimum CPU consumption):

If in device mode (only), the control endpoint can instead be managed via interrupts entirely by the library by defining the INTERRUPT_CONTROL_ENDPOINT token and passing it to the compiler via the -D switch.

See also:
USB Events for more information on the USB events.

Variable Documentation

Structure containing the last received Control request when in Device mode (for use in user-applications inside of the EVENT_USB_Device_UnhandledControlRequest() event, or for filling up with a control request to issue when in Host mode before calling USB_Host_SendControlRequest().

volatile uint8_t USB_CurrentMode

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.
volatile bool USB_IsInitialized

Indicates if the USB interface is currently initialized but not necessarily connected to a host or device (i.e. if USB_Init() has been run). If this is false, all other library globals are invalid.

Note:
This variable should be treated as read-only in the user application, and never manually changed in value.
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.

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