USB Host Mode Development Based On Embedded System USB

USB interface has a variety of features, such as easy to use, high data transmission rate and supporting plug-and-play. However, due to the complexity in USB interface protocol, involving a wide area, especially many sorts in software, a wide range of USB chip, which makes it very difficult in the development of USB devices. However, with gradual expanse in the application areas of USB, people's expectation for USB is also getting higher and higher. It is hoped that USB be used in various fields of computers, in particular in the field of mobile data, in which USB can be applied in the field with the absence of the PC through direct communication with USB devices. How to apply USB in the field of embedded field and achieve peer-to-peer communications of has become a hot research field.In this paper, we consider it as the purpose to realize that arbitrary wave generator has the function of USB host mode. Besides, we choose ADS1.2/Embest as software development environment, use chip HMS30C7202 as controller chip and select Cypress's SL811HS as USB controller chip.(1) We analyzed USB1.1 agreement, conducted analysis mainly on USB1.1 agreement on the basis of the research of the architecture of USB, USB bus topology, USB bus physical interface, logic tiers of USB system, data communications flow of USB bus and other basic elements.(2) We conducted systematic analysis of the development process of embedded system, and designed the USB host mode hardware system of arbitrary wave generator. We analyzed interference factors, and took anti-jamming measures separately on the choice of components, shielding the external electromagnetic radiation, crystal stability and PCB circuit boards to guarantee reliable operation of system.(3) We conducted system software design, did research and analysis of the Bulk-Only transfer protocol, SCSI command sets and construction of FAT file system. The system completed design on USB host controller driver program, core driver program and user software, and realized functions of the enumeration of the equipment, configuration, and other functions. System supported Mass Storage class agreement, established a file system interface and achieved reading of USB document through sending SCSI orders. The paper did research and development on of USB host mode in embedded system, realized the construction of embedded USB host system, added USB host functions in the control panel of arbitrary wave generator and achieved processing to the waveform data stored in the U-disk, which is of great significance for the promotion and practical value on the development of embedded USB host and making the application of USB absent form PC.