Method and device for erasure balance of Nand Flash

Abstract

A method and an apparatus for Nand Flash erase leveling are disclosed. The method includes the following steps: setting at least a first erase times threshold and a second erase times threshold which is less than or equal to the first erase times threshold; setting at least a first use frequency threshold and a second use frequency threshold which is more than or equal to the first use frequency threshold; assigning the physical blocks of the Nand Flash into different physical block regions according to the first erase times threshold, the second erase times threshold, the first use frequency threshold and the second use frequency threshold; and mapping logical blocks to the physical blocks in the corresponding physical block regions respectively according to the use frequency and the original mapping relationship of the logical blocks of the Nand Flash. The solution solves the problem that the storage space of the Nand Flash is reduced as the erase times of partial physical blocks exceed the set (rated) erase times of the Nand Flash physical blocks, thus increases the life of the Nand Flash.

Description

technical field [0001] The invention relates to the technical field of memory, in particular to a method and device for erasing and equalizing a Nand Flash. Background technique [0002] Nand Flash has the characteristics of low cost, large capacity and good stability, and is widely used in the embedded field. [0003] The physical structure of Nand Flash is composed of page structure and block structure. The size of a page is 512Bytes, and each page has an additional area of ​​16Bytes Spare Area. This area is not a data area and can be used to store some information related to the page, such as Check code, etc.; a block consists of 32 adjacent pages (or 64 pages), which is 16KB (or 32KB). A page is the basic unit of a read operation, and a block is the basic unit of an erase operation. Before writing to an area, if the area has been written to before, the entire block containing the area needs to be erased first (erase first, then write). Nand Flash needs to erase the bl...

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