USBTask.h File Reference

#include <avr/io.h>
#include <avr/interrupt.h>
#include <util/atomic.h>
#include <stdbool.h>
#include <stddef.h>
#include "../../../Scheduler/Scheduler.h"
#include "../LowLevel/LowLevel.h"
#include "../LowLevel/HostChapter9.h"
#include "../LowLevel/USBMode.h"
#include "Events.h"
#include "StdDescriptors.h"
#include "../LowLevel/HostChapter9.h"
#include "../LowLevel/LowLevel.h"

Functions

 RAISES_EVENT (USB_Connect)
 RAISES_EVENT (USB_DeviceAttached)
 RAISES_EVENT (USB_DeviceUnattached)
 RAISES_EVENT (USB_DeviceEnumerationFailed)
 RAISES_EVENT (USB_DeviceEnumerationComplete)
 RAISES_EVENT (USB_Disconnect)
 TASK (USB_USBTask)

Variables

volatile bool USB_IsConnected
volatile bool USB_IsInitialized
volatile bool USB_IsSuspended
volatile uint8_t USB_HostState

Detailed Description

Main library USB management task for both Host and Device mode operations. This contains the master USB_USBTask task which should be periodically run to service both host and device USB projects.

Function Documentation

RAISES_EVENT ( USB_Disconnect   ) 

This module raises the USB Disconnect event when an attached USB device is removed from the USB bus.

See also:
Events.h for more information on this event.

RAISES_EVENT ( USB_DeviceEnumerationComplete   ) 

This module raises the USB Device Enumeration Complete event when in host mode, and an attached USB device has been successfully enumerated and ready to be used by the user application.

See also:
Events.h for more information on this event.

RAISES_EVENT ( USB_DeviceEnumerationFailed   ) 

This module raises the USB Device Enumeration Failed event when in host mode, and an attached USB device has failed to successfully enumerated.

See also:
Events.h for more information on this event.

RAISES_EVENT ( USB_DeviceUnattached   ) 

This module raises the USB Device Unattached event when in host mode, and a device is removed from the AVR's USB interface.

See also:
Events.h for more information on this event.

RAISES_EVENT ( USB_DeviceAttached   ) 

This module raises the USB Device Attached event when in host mode, and a device is attached to the AVR's USB interface.

See also:
Events.h for more information on this event.

RAISES_EVENT ( USB_Connect   ) 

This module raises the USB Connect event when a USB device has been connected whilst in host mode, but not yet enumerated.

See also:
Events.h for more information on this event.

TASK ( USB_USBTask   ) 

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, scheduler (e.g. the simple LUFA Scheduler), fast timer ISR or the main user application loop.

The USB task must be serviced within 50mS in all modes, when needed. The task may be serviced at all times, or (for minimum CPU consumption):

  • In device mode, it may be disabled at startup, enabled on the firing of the USB_Connect event and disabled again on the firing of the USB_Disconnect event.

  • In host mode, it may be disabled at startup, enabled on the firing of the USB_DeviceAttached event and disabled again on the firing of the USB_DeviceUnattached event.

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


Variable Documentation

volatile uint8_t USB_HostState

Indicates the current host state machine state. When in host mode, this indicates the state via one of the values of the USB_Host_States_t enum values in Host.h.

This value may be altered by the user application to implement the HOST_STATE_Addressed, HOST_STATE_Configured, HOST_STATE_Ready and HOST_STATE_Suspended states which are not implemented by the library.

Note:
This global is only present if the user application can be a USB host.

volatile bool USB_IsConnected

Indicates if the USB interface is currently connected to a host if in device mode, or to a device while running in host mode.

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

For the smaller USB AVRs (AT90USBXX2) with limited USB controllers, VBUS is not available to the USB controller. this means that the current connection state is derived from the bus suspension and wake up events by default, which is not always accurate (host may suspend the bus while still connected). If the actual connection state needs to be determined, VBUS should be routed to an external pin, and the auto-detect behaviour turned off by passing the NO_LIMITED_CONTROLLER_CONNECT token to the compiler via the -D switch at compile time. The connection and disconnection events may be manually fired by RAISE_EVENT(), and the USB_IsConnected global changed manually.

volatile bool USB_IsInitialized

Indicates if the USB interface is currently initialized but not neccesarily 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 bool USB_IsSuspended

Indicates if the USB interface is currently suspended by the host when in device mode. When suspended, the device should consume minimal power, and cannot communicate to the host. If Remote Wakeup is supported by the device and USB_RemoteWakeupEnabled is true, suspension can be terminated by the device by issuing a Remote Wakup request.

Note:
This global is only present if the user application can be a USB device.

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


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