USB Descriptors
[USB - LUFA/Drivers/USB/USB.h]


Data Structures

struct  USB_Descriptor_Header_t
struct  USB_Descriptor_Device_t
struct  USB_Descriptor_Configuration_Header_t
struct  USB_Descriptor_Interface_t
struct  USB_Descriptor_Interface_Association_t
struct  USB_Descriptor_Endpoint_t
struct  USB_Descriptor_String_t

Modules

 Configuration Descriptor Parser

Defines

#define NO_DESCRIPTOR   0
#define USB_CONFIG_POWER_MA(mA)   (mA >> 1)
#define USB_STRING_LEN(str)   (sizeof(USB_Descriptor_Header_t) + (str << 1))
#define VERSION_BCD(x)
#define LANGUAGE_ID_ENG   0x0409
#define ENDPOINT_DESCRIPTOR_DIR_IN   0x80
#define ENDPOINT_DESCRIPTOR_DIR_OUT   0x00
#define USB_CONFIG_ATTR_BUSPOWERED   0x80
#define USB_CONFIG_ATTR_SELFPOWERED   0xC0
#define USB_CONFIG_ATTR_REMOTEWAKEUP   0xA0
#define ENDPOINT_ATTR_NO_SYNC   (0 << 2)
#define ENDPOINT_ATTR_ASYNC   (1 << 2)
#define ENDPOINT_ATTR_ADAPTIVE   (2 << 2)
#define ENDPOINT_ATTR_SYNC   (3 << 2)
#define ENDPOINT_USAGE_DATA   (0 << 4)
#define ENDPOINT_USAGE_FEEDBACK   (1 << 4)
#define ENDPOINT_USAGE_IMPLICIT_FEEDBACK   (2 << 4)
#define DESCRIPTOR_ADDRESS(Descriptor)   ((void*)&Descriptor)

Enumerations

enum  USB_DescriptorTypes_t {
  DTYPE_Device = 0x01,
  DTYPE_Configuration = 0x02,
  DTYPE_String = 0x03,
  DTYPE_Interface = 0x04,
  DTYPE_Endpoint = 0x05,
  DTYPE_DeviceQualifier = 0x06,
  DTYPE_Other = 0x07,
  DTYPE_InterfacePower = 0x08,
  DTYPE_InterfaceAssociation = 0x0B
}

Functions

 RAISES_EVENT (USB_DeviceError)
uint16_t USB_GetDescriptor (const uint16_t wValue, const uint8_t wIndex, void **const DescriptorAddress) ATTR_WARN_UNUSED_RESULT ATTR_WEAK ATTR_NON_NULL_PTR_ARG(3)

Detailed Description

Standard USB device descriptor defines and retrieval routines, for USB devices. This module contains structures and macros for the easy creation of standard USB descriptors in USB device projects.

All standard descriptors have their elements named in an identical manner to the official USB specification, however slightly more verbose alternate (non-standard) names are also supplied if the macro USE_NONSTANDARD_DESCRIPTOR_NAMES is defined in the user project makefile and passed to the compiler at compilation time using the -D option.

The non-standard names are documented here - if USE_NONSTANDARD_DESCRIPTOR_NAMES is not defined, then all descriptors will contain elements named identically to the official USB specification. The alternately named descriptor elements are placed in the same order inside the descriptor structures as their officially named counterparts, thus they can be correlated easily with the official USB specification.


Define Documentation

#define DESCRIPTOR_ADDRESS ( Descriptor   )     ((void*)&Descriptor)

Gives a void pointer to the specified descriptor (of any type).

#define ENDPOINT_ATTR_ADAPTIVE   (2 << 2)

Can be masked with other endpoint descriptor attributes for a USB_Descriptor_Endpoint_t descriptor's Attributes value to indicate that the specified endpoint is adaptive.

See also:
The USB specification for more details on the possible Endpoint attributes.

#define ENDPOINT_ATTR_ASYNC   (1 << 2)

Can be masked with other endpoint descriptor attributes for a USB_Descriptor_Endpoint_t descriptor's Attributes value to indicate that the specified endpoint is asynchronous.

See also:
The USB specification for more details on the possible Endpoint attributes.

#define ENDPOINT_ATTR_NO_SYNC   (0 << 2)

Can be masked with other endpoint descriptor attributes for a USB_Descriptor_Endpoint_t descriptor's Attributes value to indicate that the specified endpoint is not synchronized.

See also:
The USB specification for more details on the possible Endpoint attributes.

#define ENDPOINT_ATTR_SYNC   (3 << 2)

Can be masked with other endpoint descriptor attributes for a USB_Descriptor_Endpoint_t descriptor's Attributes value to indicate that the specified endpoint is synchronized.

See also:
The USB specification for more details on the possible Endpoint attributes.

#define ENDPOINT_DESCRIPTOR_DIR_IN   0x80

Can be masked with an endpoint address for a USB_Descriptor_Endpoint_t endpoint descriptor's EndpointAddress value to indicate to the host that the endpoint is of the IN direction (i.e, from device to host).

#define ENDPOINT_DESCRIPTOR_DIR_OUT   0x00

Can be masked with an endpoint address for a USB_Descriptor_Endpoint_t endpoint descriptor's EndpointAddress value to indicate to the host that the endpoint is of the OUT direction (i.e, from host to device).

#define ENDPOINT_USAGE_DATA   (0 << 4)

Can be masked with other endpoint descriptor attributes for a USB_Descriptor_Endpoint_t descriptor's Attributes value to indicate that the specified endpoint is used for data transfers.

See also:
The USB specification for more details on the possible Endpoint usage attributes.

#define ENDPOINT_USAGE_FEEDBACK   (1 << 4)

Can be masked with other endpoint descriptor attributes for a USB_Descriptor_Endpoint_t descriptor's Attributes value to indicate that the specified endpoint is used for feedback.

See also:
The USB specification for more details on the possible Endpoint usage attributes.

#define ENDPOINT_USAGE_IMPLICIT_FEEDBACK   (2 << 4)

Can be masked with other endpoint descriptor attributes for a USB_Descriptor_Endpoint_t descriptor's Attributes value to indicate that the specified endpoint is used for implicit feedback.

See also:
The USB specification for more details on the possible Endpoint usage attributes.

#define LANGUAGE_ID_ENG   0x0409

String language ID for the English language. Should be used in USB_Descriptor_String_t descriptors to indicate that the English language is supported by the device in its string descriptors.

#define NO_DESCRIPTOR   0

Indicates that a given descriptor does not exist in the device. This can be used inside descriptors for string descriptor indexes, or may be use as a return value for GetDescriptor when the specified descriptor does not exist.

#define USB_CONFIG_ATTR_BUSPOWERED   0x80

Can be masked with other configuration descriptor attributes for a USB_Descriptor_Configuration_Header_t descriptor's ConfigAttributes value to indicate that the specified configuration can draw its power from the host's VBUS line.

#define USB_CONFIG_ATTR_REMOTEWAKEUP   0xA0

Can be masked with other configuration descriptor attributes for a USB_Descriptor_Configuration_Header_t descriptor's ConfigAttributes value to indicate that the specified configuration supports the remote wakeup feature of the USB standard, allowing a suspended USB device to wake up the host upon request.

#define USB_CONFIG_ATTR_SELFPOWERED   0xC0

Can be masked with other configuration descriptor attributes for a USB_Descriptor_Configuration_Header_t descriptor's ConfigAttributes value to indicate that the specified configuration can draw its power from the device's own power source.

#define USB_CONFIG_POWER_MA ( mA   )     (mA >> 1)

Macro to calculate the power value for the device descriptor, from a given number of milliamps.

#define USB_STRING_LEN ( str   )     (sizeof(USB_Descriptor_Header_t) + (str << 1))

Macro to calculate the Unicode length of a string with a given number of Unicode characters. Should be used in string descriptor's headers for giving the string descriptor's byte length.

#define VERSION_BCD (  ) 

Value:

((((VERSION_TENS(x) << 4) | VERSION_ONES(x)) << 8) | \
                                                      ((VERSION_TENTHS(x) << 4) | VERSION_HUNDREDTHS(x)))
Macro to encode a given four digit floating point version number (e.g. 01.23) into Binary Coded Decimal format for descriptor fields requiring BCD encoding, such as the USB version number in the standard device descriptor.


Enumeration Type Documentation

Enum for the possible standard descriptor types, as given in each descriptor's header.

Enumerator:
DTYPE_Device  Indicates that the descriptor is a device descriptor.
DTYPE_Configuration  Indicates that the descriptor is a configuration descriptor.
DTYPE_String  Indicates that the descriptor is a string descriptor.
DTYPE_Interface  Indicates that the descriptor is an interface descriptor.
DTYPE_Endpoint  Indicates that the descriptor is an endpoint descriptor.
DTYPE_DeviceQualifier  Indicates that the descriptor is a device qualifier descriptor.
DTYPE_Other  Indicates that the descriptor is of other type.
DTYPE_InterfacePower  Indicates that the descriptor is an interface power descriptor.
DTYPE_InterfaceAssociation  Indicates that the descriptor is an interface association descriptor.


Function Documentation

RAISES_EVENT ( USB_DeviceError   ) 

This module raises the Device Error event while in device mode, if the USB_GetDescriptor() routine is not hooked in the user application to properly return descriptors to the library.

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

uint16_t USB_GetDescriptor ( const uint16_t  wValue,
const uint8_t  wIndex,
void **const   DescriptorAddress 
)

Function to retrieve a given descriptor's size and memory location from the given descriptor type value, index and language ID. This function MUST be overridden in the user application (added with full, identical prototype and name except for the ATTR_WEAK attribute) so that the library can call it to retrieve descriptor data.

Parameters:
wValue The type of the descriptor to retrieve in the upper byte, and the index in the lower byte (when more than one descriptor of the given type exists, such as the case of string descriptors). The type may be one of the standard types defined in the DescriptorTypes_t enum, or may be a class-specific descriptor type value.
wIndex The language ID of the string to return if the wValue type indicates DTYPE_String, otherwise zero for standard descriptors, or as defined in a class-specific standards.
DescriptorAddress Pointer to the descriptor in memory. This should be set by the routine to the location of the descriptor, found by the DESCRIPTOR_ADDRESS() macro.
Note:
By default, the library expects all descriptors to be located in flash memory via the PROGMEM attribute. If descriptors should be located in RAM or EEPROM instead (to speed up access in the case of RAM, or to allow the descriptors to be changed dynamically at runtime) either the USE_RAM_DESCRIPTORS or the USE_EEPROM_DESCRIPTORS tokens may be defined in the project makefile and passed to the compiler by the -D switch.
Returns:
Size in bytes of the descriptor if it exists, zero or NO_DESCRIPTOR otherwise


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