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RL-ARM User's Guide (MDK v4)

RL-RTX RL-FlashFS RL-TCPnet RL-CAN RL-USB RL-USB for USB Device Applications RL-USB Device Library RL-USB Device Features RL-USB Device Software Stack RL-USB Device Functions RL-USB Device Source Files RL-USB Device Configuration Audio Device (ADC) Options Communication Device (CDC) - ACM Options Human Interface Device (HID) Options Mass Storage Device (MSC) Options Create USB Device Applications Create ADC Applications Create CDC ACM Applications Create HID Applications Create MSC Applications Create Composite Applications Test USB Device Applications Compliance Tests Test HID Client Application RL-USB for USB Host Applications RL-USB Host Library RL-USB Host Features RL-USB Host Software Stack RL-USB Host Functions RL-USB Host Source Files RL-USB Host Configuration Host Controller Driver Selection Host Controller Driver Configuration Host Class Driver Selection Create USB Host Applications Create USB Host HID Applications HID_Kbd Example Create USB Host MSC Applications Create USB Host Class Driver RL-USB Host Constants and Structures Error constants Speed constants Transaction Packet Type constants Transaction Error Type constants USB Request Block structure (USBH_URB) Endpoint structure (USBH_EP) Driver Capabilites structure (USBH_HCI_CAP) Device Class Instance structure (USBH_DCI) Host Controller Instance structure (USBH_HCI) Host Controller Driver structure (USBH_HCD) USB Concepts USB Transfer Rates USB Network Basic Communication Model USB Protocol Control Transfer Interrupt Transfer Isochronous Transfer Bulk Transfer Descriptors Device Configuration Device Descriptor Configuration Descriptor Interface Descriptor Endpoint Descriptor Device Qualifier Descriptor Example Programs Library Reference Appendix

Configuration Descriptor

The Configuration Descriptor contains information about the device’s power requirements and the number of interfaces it can support. A device can have multiple configurations. The host can select the configuration that best matches the requirements of the application software it is running.

Offset Field Size Value Description
0 bLength 1 Number Size of this descriptor in bytes.
1 bDescriptorType 1 Constant Configuration Descriptor Type.
2 wTotalLength 2 Number 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.
4 bNumInterfaces 1 Number Number of interfaces supported by this configuration.
5 bConfigurationValue 1 Number Value to use as an argument to the SetConfiguration() request to select this configuration.
6 iConfiguration 1 Index Index of string descriptor describing this configuration.
7 bmAttributes 1 Bitmap Configuration characteristics
D7: Reserved (set to one)
D6: Self-powered
D5: Remote Wakeup
D4...0: Reserved (reset to zero)

D7 is reserved and must be set to one for historical reasons.

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. If a device configuration supports remote wakeup, D5 is set to one.
8 bMaxPower 1 mA 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).
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