A truly tiny and beautiful, ultra-fast and modern USB stack for embedded systems.
XRUSB is a standalone, modern C++ USB protocol stack. It is provided both as a LibXR subtree and as an independent repository. XRUSB focuses on portability, high performance, and easy integration.
- Modern C++ Implementation: Written in C++17, using classes and template-based modular encapsulation for easy extension.
- Lock-Free Data Structures: All data transfers and event handling are lock-free and thread-safe for maximum efficiency.
- Double Buffering Mechanism: Fully utilizes hardware/software double buffers and DMA. Alternating read/write greatly increases data throughput.
- Dynamic Endpoint Allocation: Endpoints are allocated on demand during enumeration; multiple classes can automatically manage and reuse endpoints to avoid resource waste.
- One-Time Memory Allocation: All memory is determined at compile time and allocated once at construction. No redundant space is reserved for strings/descriptors.
- Interrupt-Driven: Operates fully by hardware interrupts, with no reliance on polling or background threads.
- Interrupt-Safe: Driver functions can be called directly from ISR (Interrupt Service Routine).
- Optimized Memory Copy: Achieves higher throughput for bulk transfers and descriptor processing.
This repository only contains platform-independent stack code. For platform-specific device drivers, please refer to the corresponding drivers in libxr, such as driver/st/stm32_usb_ep.cpp and driver/ch/ch32_usb_endpoint_otghs.cpp.
| Protocol | Status | Notes |
|---|---|---|
| CDC-ACM | Supported | Implemented as LibXR’s UART class |
| HID | Supported | Only standard keyboard/mouse and remote controller; other types require you to derive your own |
| UAC | Supported | Currently implements a UAC 1.0 microphone only |
TODO
| Platform | Phy | Status | Test Device |
|---|---|---|---|
| STM32 | USB_DEVICE_FS | Supported | STM32F103 |
| STM32 | USB_DRV_FS | Supported (Device) | STM32G431 |
| STM32 | USB_OTG_FS | Supported (Device) | STM32F407 |
| STM32 | USB_OTG_HS | Supported (Device) | STM32F407/STM32H750 |
| CH32 | USB_OTG_FS | Supported (Device) | CH32V307/CH32V203/CH32V208 |
| CH32 | USB_HS | Supported | CH32V307 |
Released together with the LibXR documentation.