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Technical Support
On-Line Manuals
RL-ARM User's Guide
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RL-USB for USB Device Applications
RL-USB Device Library
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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
Create MSC Applications
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Test USB Device Applications
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RL-USB for USB Host Applications
RL-USB Host Library
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RL-USB Host Source Files
RL-USB Host Configuration
Host Controller Driver Selection
Host Controller Driver Configuration
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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
RL-ARM User's Guide
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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