Abstract : USB (Universal Serial Bus) is currently the most widely used external bus architecture for connecting computers and external devices. The most commonly used devices are those adopting the USB 2.0 interface standard, and its protocol stack is the core of the entire USB 2.0 application management. This article mainly analyzes the structural characteristics of the USB 2.0 software system based on a specific platform, studies and designs a platform-independent operating system and hardware abstraction layer, and implements a protocol stack that is compatible with various platforms. Keywords : USB 2.0; USB 2.0 protocol stack; embedded platform 1. Introduction Digital television has entered a stage of comprehensive development, and set-top boxes have transformed from simple digital television signal reception to multi-functional features. Electronic program guides, pay-per-view, instant pay-per-view, quasi-video-on-demand, data broadcasting, Internet access, email, video-on-demand, IP telephony, and video telephony will be implemented on the set-top box platform. With the development of functional features, the capacity and requirements for data processing are becoming increasingly higher. Traditional ISA, serial ports, and parallel ports are no longer suitable for the development requirements of interactive set-top boxes. USB 2.0 has excellent features such as hot-plugging, plug-and-play, shared, small size, saving system resources, flexibility, low cost, high reliability, power supply, compatibility, and high-speed transmission, making it an inevitable choice for the new generation of set-top boxes. Currently, the main operating systems used for set-top boxes are μclinux, μCOS-II, VxWorks, etc. These systems do not contain USB protocol stacks, and their USB 2.0 protocol stacks are designed and implemented independently. Researching and designing a universal and highly portable protocol stack that can be used on these platforms will have great practical significance for the development of set-top boxes. 2. Introduction to USB 2.0 Protocol 2.1 Brief Description of USB System A USB system is mainly defined as three parts: USB interconnection; USB devices; USB host. The bus topology, internal hierarchical relationship, data flow mode, and USB scheduling [1]. Research and Design of Universal USB 2.0 Protocol Stack for Multiple Embedded Platforms Full Text Download