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Technical Support
On-Line Manuals
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
Descriptors
USB devices report their attributes using descriptors. A descriptor is a data structure with a defined format. Each descriptor begins with a byte-wide field containing the total number of bytes in the descriptor followed by a byte-wide field identifying the descriptor type.
This is not a complete list of all the possible descriptors a USB host can request. However, as a minimum, the USB device must provide the device descriptor, configuration descriptor, interface descriptor, and three endpoint descriptors.
- Device Configuration explains the device configuration options and the structure of the descriptors.
- Device Descriptor describes the basic information that identifies a device.
- Configuration Descriptor describes the power requirements and the number of interfaces a device can contain.
- Interface Descriptor describes the collection of endpoints and the interfaces a device can have.
- Endpoint Descriptor specifies the attributes of an endpoint.
- Device Qualifier Descriptor describes the alternative information needed when the device operates in different speed modes.
The USB Host sends setup requests as soon as the device has joined the USB network. The device will be instructed to select a configuration and an interface to match the needs of the application running on the USB Host. Once a configuration and an interface have been selected, the device must service the active endpoints to exchange data with the USB Host.
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