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Technical Support
On-Line Manuals
RL-ARM User's Guide (MDK v4)
RL-RTX
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RL-USB
RL-USB for USB Device Applications
RL-USB Device Library
RL-USB Device Features
RL-USB Device Software Stack
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RL-USB Device Source Files
RL-USB Device Configuration
Audio Device (ADC) Options
Communication Device (CDC) - ACM Options
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Create USB Device Applications
Create ADC Applications
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Create HID Applications
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Create Composite Applications
Test USB Device Applications
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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
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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
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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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