Study On A General-Purpose USB Interface System For The Embedded Systems

Becausee of the widely using of the embedded system, the embedded devices which used in consumer and business electronic products become the new tide of the development. Embedded technology provides information on products ranging from single-board computers and digital I/O cards to industry equipment and even space shuttle. However, the difference between the operating systems may make it difficult for technician to upgrade and transplant. Since each function may correspond with one special operating system.Today is the day of information. One of the topics of the development of the embedded devices is that how to make an effective real time information collection and transmission. So the USB interface, with the advantage of convenience and high speed which used in embedded devices, becomes the trend of the development. Alough the principle of the USB Transfer Protocol is the same in every devices, the realization is different with each other. Well, the application is so pertinent, since systems are not the same in different embedded devices. Actually, we will have difficulty in upgrading and transplanting.So to resolve this problem, one scheme was raised. We peel off the software from the operating system and make it as one firmware in the integrated circuit. Well, the circuit module looks like just a black-box which only provides one interface for the operating system above it. Because the USB function is integrated in the module,it is convinient for the operating system to control. This paper talks about the basic principle and knowledge of USB first, which includs the structure of the hardware and the working principle. Subsequently, it analyses the feasibility of using"USB interface chip+MCU+dual RAM"to design the USB module . Based on the information introduced previous, it then focuses on the USB module's software framework and design of FAT file system. I also give out the arrangement of the software from the driver to the out interface. However, the file system was taken for one single chapter, bacause of its importance.At the last chapter, the implement and test process of each module in the system has been described. From analyzing the data and diagram, we find the scheme which can be applied for most embed platforms is not difficult but very feasible. And a view of the development of USB in the embedded device has been made.