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This paper examines the how multimedia digital set-top box system , increase the embedded USB (Universal Serial Bus) host interface support , as well as the associated upper application . First, at home and abroad the latest progress in the design of embedded USB host and related USB products , on this basis , to explore the two USB host interface options : (1) USB host controller CPU ( 2 ) ( USB host controller MCU ) CPU . After considering the advantages and disadvantages of the two programs , the use of the program ( 1 ) to the USB host interface , and chosen to meet the USB1.1 protocol standards USB host the controller chip SL811HS to design the hardware circuit . Next , explore the implementation of USB host protocol stack software system , the difficulty of the whole system design and key . USB protocol stack structure , current implementations are basically similar , including the PC, such as windows and linux system , they are commonly used by the hierarchy . The sake of convenience , designed and implemented with reference to the earlier version of the kernel source code in linux USB driver system design , and make the appropriate changes to meet the requirements of embedded real-time systems . In addition, due to the original design on the digital set-top boxes to support removable storage devices , the protocol stack without MassStorage device class device class ( HID class ) , and does not support the ISO ( synchronous transmission ) transmission , but because the entire modular drive system is very good, these features can easily be extended to up . Finally, the USB host interface hardware circuit design and the corresponding drive system to explore the upper layer applications , such as file based on the DVB-S broadcast control system , based on the USB removable storage devices , USB file storage - based MP3 player design the set-top box software upgrades , and so on . Meanwhile, a performance test , and comparative analysis of the two USB host interface implementations , various parameters have reached the design requirements . For various problems that arise in the design process , such as time-out interference and so on, this article also last a more detailed analysis , and lists the corresponding solution of the concrete realization of these issues .
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