描述符——配置描述符

描述符定义

描述符实现

/**
 * @brief USB configuration descriptor.
 */
typedef struct __attribute__ ((packed))
{
    uint8_t  bLength             ; /**< Size of this descriptor in bytes. */
    uint8_t  bDescriptorType     ; /**< CONFIGURATION Descriptor Type. */
    uint16_t wTotalLength        ; /**< Total length of data returned for this configuration. Includes the combined length of all descriptors (configuration, interface, endpoint, and class- or vendor-specific) returned for this configuration. */

    uint8_t  bNumInterfaces      ; /**< Number of interfaces supported by this configuration. */
    uint8_t  bConfigurationValue ; /**< Value to use as an argument to the SetConfiguration() request to select this configuration. */
    uint8_t  iConfiguration      ; /**< Index of string descriptor describing this configuration. */
    uint8_t  bmAttributes        ; /**< Configuration characteristics \n D7: Reserved (set to one)\n D6: Self-powered \n D5: Remote Wakeup \n D4...0: Reserved (reset to zero) \n D7 is reserved and must be set to one for historical reasons. \n A device configuration that uses power from the bus and a local source reports a non-zero value in bMaxPower to indicate the amount of bus power required and sets D6. The actual power source at runtime may be determined using the GetStatus(DEVICE) request (see USB 2.0 spec Section 9.4.5). \n If a device configuration supports remote wakeup, D5 is set to one. */
    uint8_t  bMaxPower           ; /**< Maximum power consumption of the USB device from the bus in this specific configuration when the device is fully operational. Expressed in 2 mA units (i.e., 50 = 100 mA). */
}usb_desc_configuration_t;
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描述符含义

• 配置描述符决定有多少个接口