Arm-based Embedded Data Storage Systems Research

With the constant development of electronic technology, embedded system is increasingly and widely used in such type of electronic product as control, consumption, communication, etc. Embedded technology is contacted with people's life more and more closely. At the same time, the requirement of storage device is also developing due to the development of hardware of computer and the increasing of data. This paper has studied data storage and exchange in embedded system deeply, and has put forward to a set of intact design plan of data storage and exchange in embedded system, and has introduced its realization course in detail.Flash memories have been widely used due to their small size, low power consumption, characterized by stable performance in portable electronic products. Flash memory mainly has two forms: Nor Flash and Nand Flash. Nor Flash supports XIP-the codes can be executed directly in the chip, and high reading speed. Nand Flash memory has high density, large capacity, simple production technology, and the high performance-price ratio. However, its control is complex and has a certain degree of bad blocks. The SD card, a portable memory card which has big capacity, is popular in recent years. In this system, we use Flash and SD card as the data storage medium. In the choice of storage medium, we use Flash memory witch is small, high-capacity and low cost inside the system. A combination of Nor flash and Nand Flash is used in the system. We store the program of system related data on Nor Flash, and users'data on Nand Flash. Use SD card witch is high security, high capacity and good performance to expand storage capacity. Based on ARM series MCU of Samsung, realized the design of the hardware circuit of Flash memory and SD card, and the design of the low level driver.In order to manage the data on the storage medium effectively, and the convenience of data exchange with PC, one standard form must be adopted to organize the data, which needs to store the data in the form of file with the file system. In this paper, we propose the data management requirements based on the characteristics of Flash, then analyze a series of strategies and mechanisms about data store, power failure protection, wear leveling, garbage collection and etc, and optimize these mechanisms to achieve. We use FAT16 that is widely supported by major operating system(Windows, Linux, etc.) to manage the data on SD card. Accomplish almost all API functions such as formatting magnetic disc, reading and writing file, etc, and realized the high-speed data exchange between embedded system and PC.