The Design And Implementation Of USB Host System Based On μC/OS-Ⅱ

With fast development and wide application of movable devices in different fields nowadays, USB and port techniques have become indispensable parts of this technology, thus, getting more and more attention, soon becoming a public concern. Enormously applied in industrial massive-manufacturing as well as in people's daily life, embedded system is a type of specialized computer systems,comprising logically interrelated integration of base hard wares, real-time operating systems and applicable soft wares. Therefore, researches and advancement of embedded USB host systems have become one of the hottest and most enchanting branches in people's eyes.As a sort of newly developed embedded real-time operating system,μC/OS-Ⅱsystem stands out in application among all embedded devices for its unique qualities as follows: free source code, oriented small or middle scale application, preemptive kernel, multitask and preferable portability. In light of what's mentioned above, this paper has setμC/OS-Ⅱsystem as a major context for basic designing and developing of hard/soft wares. This paper aims to solve problems resulting from inconvenient indirect-communication between USB devices with a bold proposal of introducing a USB host system based on embeddedμC/OS-Ⅱkernel.This paper elaborates on a USB host system with ARM kernel processor. This system has achieved several goals, that, core drive programs of USB, drive programs for host system controlling, user program, protocols supporting Mass Storage devices, and establishment of refined FAT file system with which file data can be read from FLASH discs and then be sent to PC on display through interface RS-232.According to standards of low cost, little consumption and fast speed, this paper has built a USB host system with Samsung's S3C44BOX chip as MCU and Cypress's SL811HS chip as main controlling chip. As for soft wares, this system fulfills the design and application of inter-USB drive program controlling, core drive program and user soft wares. Besides, the system realizes device enumeration, configuration and so on, and establishes Mass Storage protocols and FAT file system.After several months' design and testing, we have achieved what was set in the beginning. The test result indicated that USB drive program together with circuit module can be run successfully in context ofμC/OS-Ⅱoperating system and related running situation, then carries out U-disc device testing and reading/writing operation, hence, meeting the original design purpose of embedded USB host system module.