RTUSB-32 - Real-Time Embedded USB Host Stack

RTUSB-32 contains the core USB host protocol stack, the required host controller device drivers, a low-level communication API and high-level class drivers. Full source code is available. RTUSB-32 is suitable for implementing USB hosts, not USB devices.

Features

USB 1.1 and 2.0
Both USB versions currently in use are supported.
UHCI, OHCI, and EHCI Host Controllers
The dominant USB 1.1 and 2.0 host controller types are supported. These controller types are always supported, regardless of their respective vendor or model.
Transfer Types Control, Bulk, Interrupt, and Isochronous
All USB data transfer types/protocols can be used to support both high throughput and real-time oriented devices.
Low-, Full-, and High-Speed Data Transfer
Up to 12 Mb/s on USB 1.1 and 480 Mb/s on USB 2.0 buses are supported.
No Copy
RTUSB-32 does not copy data transferred to or from a device. Even if the buffers supplied by the application reside in the virtual address space, data transfers are always performed by DMA to/from the application's buffer. Even at very high data throughput, no CPU time is consumed to transfer the data.
Plug-and-Play and Hot Plugging
RTUSB-32 automatically detects USB devices being added and removed from the bus and calls application supplied callbacks for each such event. The application can then decide whether to enable and operate the device or not. RTUSB-32 supplies functions to query a device's name, vendor, class, descriptors, interfaces, endpoints, etc.
Class Drivers
RTUSB-32 provides high-level class drivers for keyboards, mice, touch screens, printers, mass storage devices (disks, memory sticks, floppies, digital cameras, CD-ROMs, DVDs, etc.), and ASIX USB-Ethernet bridge devices. A hub class driver is integrated in the core USB protocol stack. Class drivers allow applications to use a device without being concerned about details such as the transfer type and speed to use, etc. The source code of the class drivers is included with RTUSB-32. The mass storage device class driver can be used by a file system such as RTFiles-32. The USB-Ethernet bridge drivers can be integrated with a network stack such as RTIP-32.
Low-Level API
RTUSB-32 also allows direct access to a device. An application can query a device's endpoints, supported transfer types and speeds, etc., and then communicate directly with the device. Thus, any USB 1.1 or 2.0 device can be used, even if no class driver is available or the device does not adhere to a standard USB class specification. Many examples are included with RTUSB-32 showing how an application can query and operate arbitrary USB devices.
Asynchronous I/O
RTUSB-32 performs I/O in the background. The application starts I/O operations and can then perform other tasks and query the status of the transaction at a later time. Any number of I/O transactions can be pending simultaneously. If two or more transactions are started on the same I/O pipe, a continuous data stream can be implemented with the application processing one buffer while the other is being transferred.
Real-Time
RTUSB-32 can call application supplied callbacks when data is received from an attached device. Depending on the transfer type, such callbacks can occur periodically or asynchronously with 1 millisecond (or even 125 microseconds on USB 2.0) resolution.
Portable
RTUSB-32 is preconfigured to work with On Time RTOS-32, but can easily be ported to any other system. All OS-dependent code is placed in a configuration header file and a linkable system driver with a simple and small API containing functions for port I/O, memory management, interrupt handling, etc. RTUSB-32 is completely written in ANSI C and supports little- and big-endian CPUs. It can be configured to ensure cache coherence in software, if required. The complete source code of porting layer implementation is included with RTUSB-32 and the free RTUSB-32 Evaluation Kit.

More information about RTUSB-32 is available in the free On Time RTOS-32 Evaluation Kit. If you are specifically interested in porting RTUSB-32 to a different platform, please have a look at the RTUSB-32 Evaluation Kit.

Structure of RTUSB-32