JP2007079762A - Method for managing flash memory - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for managing a flash memory for, even when there are excess defective blocks in a flash memory, preventing it from being decided as the invalidity of use. <P>SOLUTION: The total number of normal blocks and defective blocks owned by a flash memory is calculated, and they are respectively averaged, based on the number of sections owned by the flash memory, and distributed data are recorded in the normal block. Thus, when an initializing operation is performed in the flash memory, a control chip searches the block in which the data are stored, and reads the information of the block, and stores it in an SRAM in the control chip, and prepares a correspondence table for the block in the corresponding section, based on the data stored in the SRAM. Thus, the purpose of management is achieved, and the flash memory is used with a relatively small capacity. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a kind of flash memory management method. In particular, the present invention relates to a flash memory management method in which a flash memory can be used with a relatively small capacity by adjusting the capacity of the flash memory by using the number of normal blocks in a kind of flash memory.

Non-volatile memory has evolved from MASK-ROM, OTP ROM, EPROM, and EEPROM to flash memory, but flash memory has the advantages of non-volatile memory, yet requires high access speed and power consumption. It is a rapidly growing product in the semiconductor industry because it has the feature of storing data without any problems. The industry combines control chips with flash memory to produce new storage devices such as portable media and memory cards. Flash memory has low energy consumption, non-volatility, earthquake resistance, high storage density, etc., and does not require parts such as motors and magnetic heads, so the volume can be greatly reduced. It is a notable stock of storage media that meets the needs of electronic products such as portable media and PDAs.
On the other hand, the development direction of flash memory is moving toward large capacity, and the capacity of one flash memory has already reached 512 MB. Moreover, although the number of blocks has reached 4096, there is a limit to the SRAM (Static Random Access Memory) on the control chip, so the blocks in the flash memory are managed in sections and swap operations are performed. Then, the objective of total block management is achieved, and the selection of each section is distributed to the average. For example, a flash memory having 4096 blocks is divided into 4 sections, and each section has 1024 blocks.
Although this management method simplifies management, when several defective blocks appear in the flash memory and the defective blocks are concentrated in the same section, in the process of writing data to the section, Since there is no replaceable block in the section, the flash memory becomes inaccessible at all, and the storage device created by the flash memory cannot be used.
If this happens, consumers must purchase a new storage device, which is very wasteful.
JP 2002-366423 A

The known structure has the following drawbacks.
In other words, the current flash memory has a very large capacity, reaching 4096 blocks in the case of 512 MB memory, but because the SRAM on the control chip is limited, the blocks in the flash memory are divided into sections. Managed.
However, if several bad blocks appear in the flash memory and the bad blocks are concentrated in the same section, the block that can be exchanged in the section in the process of writing data in the section. Therefore, the flash memory cannot be accessed at all, and the storage device made by the flash memory cannot be used.
The present invention provides a flash memory management method that solves the problems of the above structure.

  In order to solve the above problems, the present invention provides the following flash memory management method. It mainly uses the number of normal blocks in the flash memory, adjusts the capacity of the flash memory and the corresponding number of sections and the number of normal blocks included in each section, thus enabling the flash memory to be used with a relatively small capacity, A flash memory management method comprising a flexible space in the memory management method.

  That is, according to the first aspect of the present invention, in the flash memory management method, first, the total number of normal blocks and bad blocks in the flash memory is calculated, averaged based on the number of sections of the flash memory, and after distribution When the flash memory executes initialization, the control chip finds a block for storing the data, reads the data of the block, stores it in the SRAM in the control chip, and stores the data in the SRAM. A flash memory management method characterized in that a correspondence table is created for a block in a corresponding section based on data stored in SRAM.

  The invention according to claim 2 is the flash memory management method according to claim 1, wherein the data includes the number of sections, the number of normal blocks in each section, and border data.

According to the invention of claim 3, in the flash memory management method, when the initialization operation is executed in the flash memory for recording the number of sections, the normal block of each section, and the border data
(A) The control chip finds the number of sections in the flash memory, the number of normal blocks in each section, and the block for storing the border data, stores the data recorded in the block in the SRAM in the control chip,
(B) Based on the border and section data in SRAM, create a border and section in the flash memory,
(C) Check for normal blocks in each section,
(D) Create block correspondence table in section,
The flash memory management method is performed based on the order of steps (A) to (D).

As described above, the present invention calculates the total number of normal blocks and bad blocks that the flash memory has, averages each based on the number of sections that the flash memory has, and records it in the SRAM in the control chip. When executing the initialization operation, the control chip creates a correspondence table for the blocks in the corresponding section based on the data stored in the SRAM.
In this way, the initial purpose of management is achieved, and the flash memory can be used with a relatively small capacity. Even if there are an excessive number of defective blocks in the flash memory, it is not determined that the flash memory cannot be used.

An embodiment of a preferred flash memory management method of the present invention will be described with reference to the drawings.
As shown in FIGS. 1 and 2, before the user uses the flash memory 1, a control chip (not shown) first calculates the total number of all normal blocks 11 and bad blocks 12. Each normal block 11 is averaged based on the number of sections it has, and the number of sections, the number of normal blocks 11 in each section, border data, etc. are recorded.
When the flash memory 1 is initialized, the control chip finds the number of sections, the number of normal blocks 11 in each section, and a block for recording border data (data block in FIG. 1), reads the information of the block, The data is stored in SRAM (Static Random Access Memory) in the control chip.

When the initialization operation is performed for each section, the control chip creates a correspondence table for the blocks in the corresponding section based on the information stored in the SRAM to achieve the management purpose.
For example, if a certain flash memory 1 has 4096 blocks and the number of defective blocks 12 is 128, and if divided into 4 sections, the number of normal blocks 11 in each section is (4096-128). ) / 4 = 992.
Further, when the number of normal blocks 11 calculated from the beginning reaches 992, border recording is performed. Thus, it is possible to record in 4 sections, but the recorded contents are as follows.
F (0) = 0, ~ F (1)
F (1) -F (2),
F (2) to F (3),
F (3) -F (4) <= 4096
When the recorded contents are written in the normal block 11 and the flash memory 1 is initialized, the control chip searches for a block for storing the record, reads the information of the block, and stores it in the SRAM in the control chip. Save to. When the initialization operation is performed on the individual sections, the control chip creates a correspondence table for the blocks in the corresponding sections based on the information stored in the SRAM. In this way, the management purpose is achieved.

  When there are an excessive number of defective blocks 12 in the flash memory 1, the present invention adjusts the capacity of the flash memory 1 with respect to the number of normal blocks 11 and uses the corresponding number of sections and the number of normal blocks 11 included in each section. To do. Thus, the flash memory 1 can be used with a relatively small capacity, and a flexible space can be provided in the management of the flash memory 1.

Next, as shown in FIGS. 1, 2, and 3, when the flash memory 1 that records the number of sections, the number of normal blocks 11 in each section, and border data executes an initialization operation, the following steps are performed.
(100) The control chip finds the number of sections in the flash memory 1, the number of normal blocks 11 in each section, and a block for storing border data, and stores the data recorded in the block in the SRAM in the control chip.
(110) A border and section are created in the flash memory 1 based on the border and section data in the SRAM.
(120) Check the normal block 11 in each section.
(130) Create a block correspondence table in the section.
Thus, the flash memory 1 can be used with a relatively small capacity, and a flexible space can be provided in the management of the flash memory 1.

  Thus, when the flash memory executes the initialization operation, the control chip searches for a block for storing the data, reads out the block information, and stores it in the SRAM in the control chip. A correspondence table is created for the blocks in the corresponding section based on the data stored in the SRAM. Thus, the purpose of management is achieved, the flash memory can be used with a relatively small capacity, and even if there are excessive defective blocks in the flash memory, it is not determined that the flash memory cannot be used.

It is a block calculation instruction | indication figure of this invention. It is a block management instruction diagram of the present invention. 3 is a flowchart of initialization of a flash memory according to the present invention.

Explanation of symbols

1 Flash memory 11 Normal block 12 Bad block

Claims (3)

  In the flash memory management method, first calculate the total number of normal blocks and bad blocks in the flash memory, average each based on the number of sections that the flash memory has, and record the distributed data in the normal block, Thus, when the flash memory executes initialization, the control chip finds a block storing the data, reads the data of the block, stores it in the SRAM in the control chip, and based on the data stored in the SRAM, A flash memory management method, comprising: creating a correspondence table for a block in a corresponding section.   2. The flash memory management method according to claim 1, wherein the data includes the number of sections, the number of normal blocks in each section, and border data. In the flash memory management method, when executing the initialization operation in the flash memory that records the number of sections, normal blocks of each section, and border data,
(A) The control chip finds the number of sections in the flash memory, the number of normal blocks in each section, and the block for storing the border data, stores the data recorded in the block in the SRAM in the control chip,
(B) Based on the border and section data in SRAM, create a border and section in the flash memory,
(C) Check for normal blocks in each section,
(D) Create block correspondence table in section,
A flash memory management method, which is performed based on the order of steps (A) to (D).

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