What is USB stack?
A USB stack is a software component that implements the USB (Universal Serial Bus) protocol, facilitating communication between a host controller and USB devices.
The fundamental technology of Universal Serial Bus (USB) is defined as a hardware and protocol specification for interconnecting various devices to a host controller. This specification covers everything from the physical cables and connectors to the detailed rules for data exchange.
While the USB specification defines how devices and hosts should interact, the USB stack is the software implementation that brings this protocol to life within a computer or other host system. According to the provided definition, a USB stack is software that implements the USB protocol.
The primary role of the USB stack is to manage the communication flow over the USB bus. This involves handling low-level details like packet formatting, error detection, timing, and managing the state of connected devices. It acts as an intermediary layer between the complex USB hardware and higher-level software components.
Crucially, the USB stack provides an interface that allows user-written class drivers to communicate with USB devices. This means that software developers creating drivers for specific categories of USB devices (like Human Interface Devices, Mass Storage Devices, etc.) interact with the USB stack. The stack translates the requests from these drivers into the specific operations required by the USB protocol and hardware, and conversely, it delivers data and status information from devices to the appropriate drivers.
In summary, the USB stack is essential software that embodies the rules of the USB protocol, enabling seamless communication between a host system's software (like drivers) and the connected USB hardware devices.
