| Advanced as the supplement of the USB2.0 protocol, the USB OTG technique has greatly developed these years. It is very useful to transmit datas between the embedded devices,if there are no host devices like PC. The Set-Up-Box is a kind of the terminal devices of the digital-television. Because of the demand of the new function, nowadays ,the Set-Up-Box can not meet these requirement . It intensely needs to extend the exterior memory medium,like hard disk,USB flash disk,Compact Flash disk and so on.On the other hand, The Set-Up-Box is not independence,and need to be connected with other devices .So they can communicate with each other and work together.To resolve this problem,have studied on the newest progress of the designing of embedded USB OTG interface and relevant products carried out at present, this paper advances and designs a USB OTG module system which can be integrated in the Set-Up-Box .With this modul, the status of the Set-Up-Box can be changed in one transmission.As the host devices,the module can visit the USB flash disk,and sends UFI command which accords with the mass storage protocol. With the FAT file system,the modul can also operate at the files (like read, write, delete, establish, open) in the USB flash disk. As the slave devices,the modul accords with the USB1.1 protocol. So it can respond the request of the host devices, and transmit datas from three pipes in high speed.In this paper, the technological background on which the scheme bases is introduced at first, including the system and the main technique of USB, the supplement of OTG protocol. Then, the design plan of the whole system is discussed, including system requirement, hardware design and communication method. In the latter chapters, the paper deeply dicusses the host and slave part of the modul.It contains the design of the circuit, the framework of the software, the FAT file system, USB driver based on Linux and the design of firmware. At last, system performances test results are gave. |
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