Small-capacity secure digital (SD) card
A read-write method and small-capacity technology, which is applied to record carriers used in machines, instruments, computer components, etc., to meet the requirements for reading and writing small files and reduce costs
Active Publication Date: 2014-05-28
苏州国芯科技股份有限公司
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Problems solved by technology
If Norflash is used as a storage medium to save user files, the premise is that Norflash must support block erasing and can be decomposed into several partial block erasing
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[0015] The content of the present invention is mainly aimed at the inherent slow erasing and programming characteristics of SPI-Norflash in the software (commonly known as Firmware) running on the SD card, and the time limit of SD protocol for SD read and write (write sector time < 250ms, read sector time <100ms), use software to balance the gap between SD reading and writing and SPI-Norflash reading and writing.
[0016] The SD host mainly accesses the SD card through read and write commands. The read commands are divided into multi-block read and single-block read. A sector (512byte) request, when the multi-block read and write is completed, send a command to terminate the multi-block read and write. The SD protocol stipulates the timeout value between reading and writing sectors, so the firmware design needs to be able to make full use of the timeout value of each write sector (250ms, the value is larger).
[0017] Usually, for read and write operations, the normal SPI-Nor...
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The invention discloses a small-capacity secure digital (SD) card, which is characterized in that a Norflash is adopted as a storage medium of the SD card, wherein a driving program is operated on the SD card and comprises a block data arranging module and a block data erasing module; SD read-write sector requirement performance functions are inserted in the block data arranging module and the block data scrubbing module which are overtime, and a temporary area is arranged; the total erasing time in a Norflash block is averagely divided into m numbered sections so as to carry out sectioned erasing, wherein m is more than or equal to 16; in the sectioned erasing process, the SD read-write sector requirement performance functions are operated among partial sections; and the write sector requirement of the time is stored to the temporary area; and when next writing operation is started, data which are not written in the temporary area are processed again. In the small-capacity SD card, the Norflash is utilized as the storage medium, the time of read-write operation and erasing operation is configured reasonably and the read-write requirement of small files of clients is satisfied.
Description
technical field [0001] The invention relates to an SD card applied to various multimedia terminals such as mobile phones, in particular to a small-capacity SD card, which belongs to the field of digital consumer products. Background technique [0002] The SD, miniSD, microSD cards (TF) purchased in the general market are collectively referred to as SD cards here. Generally, NandFlash is used as the storage medium to save user files. It is fast for unit erasing (compared with Norflash), suitable for large-capacity storage files, music, video and other occasions. In the current market, due to the large demand for NandFlash, the relatively small demand for Norflash. The price of Norflash is relatively low. Norflash is characterized by small capacity, slow programming in units of bytes or Pages, and particularly slow erasing in units of Blocks (compared with NandFlash), suitable for storing programs and small-sized files, so In some occasions where only small-capacity SD cards...
Claims
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IPC IPC(8): G06K19/07
Inventor 郑茳肖佐楠匡启和王廷平聂智
Owner 苏州国芯科技股份有限公司