JP2001318824A - System for managing data of flash memory and recording medium with its program recorded - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a data managing method for stacking rewrite data in a flash memory per data kind, and reducing the number of times of data erasing on the flash memory. SOLUTION: A data management table 1 is set for each data which are likely to be rewritten in a flash memory so that it is possible to stack the rewrite data in the flash memory per data kind.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data management method for a flash memory in a memory such as a flash memory which requires erasure before data writing and has a limit on the number of erasures, and a recording medium on which a program is recorded. .

[0002]

2. Description of the Related Art Conventionally, data writing on a flash memory is performed in units of 1 Byte or 1 Word.
This is performed by ANDing the write data with the existing data. Therefore, "1" cannot be written to the bit to which "0" has been written once. Therefore, in order to write to the same address again, it is necessary to perform an erasing operation on the flash memory to return all bits to “1”.

[0003] The minimum unit that can be erased is 1 Block (a management unit defined by a flash memory device, usually: several KB). Therefore, even if 1-byte data is rewritten, it has already been written in the flash memory. Save existing data, then 1Bl
It is necessary to perform an operation of erasing the ock and rewriting the stored data. FIG. 6 shows an example of a conventional writing method on a flash memory.

However, in the conventional writing method on the flash memory, the writing time becomes longer in proportion to the erasing time of one block and the number of existing data.
Also, since the data is stored in the RAM, the longer the data is stored, the longer the Re by the CPU.
There is a problem that the possibility of data loss due to a set operation or the like increases.

As a specific example of the prior art, Japanese Patent Application Laid-Open
Japanese Patent Application Laid-Open No. 259046 discloses a method of storing data in a flash memory and a method of reading data from the flash memory which can reduce the number of times of erasing and extend the life of the memory. It can handle only a single type of data, and does not disclose rewriting of a plurality of types of data.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and sets a data management table for each piece of data that may be rewritten, thereby rewriting data for each data type. It is an object of the present invention to provide a data management method for a flash memory and a recording medium on which a program thereof is recorded, which enables stacking on a flash memory and reduces the number of times of erasing data on the flash memory.

[0007]

In order to achieve the above object, the invention according to claim 1 has a data management table for each type of data that can be rewritten, and the data management table includes a write data table. And an address table for sequentially holding the address data of the stacked data from the top address. The data table corresponds to a location on the address table where no address data is written. , Data to be newly written is written.

According to a second aspect of the present invention, in the first aspect of the invention, when address data has been written to the end of the address table, an erasing operation of a block including the data management table is performed. It is characterized by.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the data management method of the flash memory includes: means for initializing an address of the data management table; Means for reading whether or not the head data is "unwritten"; means for writing data to the head address of the data table if the result of the determination is "unwritten"; Means for writing address data of the obtained data on the data table to a head address of the address table.

According to a fourth aspect of the present invention, in the third aspect of the present invention, when it is determined that the first data is data that has been written at least once,
Means for searching the address table for address data of data written most recently on the data table, means for writing data to be newly written from the next address of the searched address data, Means for writing address data of the newly written data on the data table at a location on the address table corresponding to a location of the written data on the data table.

According to a fifth aspect of the present invention, in the invention of the fourth aspect, as a result of searching for the address data of the most recently written data on the address table, the address data is written to the end on the address table. If so, an erasing operation of the block including the data management table is performed.

According to a sixth aspect of the present invention, there is provided a process for initializing an address of a data management table provided for each type of data that may be rewritten, and a method of stacking write data included in the data management table. A process of reading the head data of the table and determining whether or not the head data is “unwritten”, and a process of writing data to the head address of the data table if the result of the determination is “unwritten” Then, the address data of the written data on the data table is written to the head address of the address table which is included in the data management table and holds the address data of the data stacked in the data table sequentially from the head address. Processing and a program for executing the program are recorded on a recording medium. To.

According to a seventh aspect of the present invention, in the invention of the sixth aspect, when the result of the determination is that the head data is data that has been written at least once,
A process of searching the address table for address data of data written most recently on the data table, a process of writing data to be newly written from the next address of the searched address data, A program for executing, at a location on the address table corresponding to a location on the data table of the written data, a process of writing address data on the data table of the newly written data. It is characterized by being recorded on a medium.

According to an eighth aspect of the present invention, in the invention according to the seventh aspect, as a result of searching for the address data of the most recently written data on the address table, the address data is written to the end on the address table. The program for executing a process of erasing a block including the data management table is recorded on a recording medium.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a data management table is set on a flash memory for each type of data that may be rewritten. By setting such a data management table, rewriting data can be stacked on the flash memory for each data type, and the number of erasures of the flash memory, which has been a cause of a problem in the related art, can be reduced.

The data management table is composed of two tables: a data table for stacking write data and an address table for sequentially holding the addresses of the stacked data from the head address. The address table manages the address data. It is possible to reduce the number of times of erasing the flash memory as much as possible.

FIG. 1 shows the manner in which data is written to the flash memory using the data management table. In this figure,
This figure shows a case where data is rewritten in the DataC data management table 1 in the Block (0th) composed of N-KB bytes. In the DataC address table 11, a portion where data is not written ("FF" in the figure) )) To write address data "01"
On the ataC data table 12, data "32" is written at a location where no data is written ("FF").

Next, the operation in the embodiment of the present invention will be described in detail with reference to the flowchart of FIG. 2 and the configuration diagrams of the data management tables of FIGS. Here, the size of the data to be written is described as 1 byte.

First, as shown in FIG. 3, the data management table 1 (data table 11, address table 1
Initialize the address in 2) (step S10)
1). Next, the head data of the address table 12 is read, and it is determined whether or not the head data is “unwritten (FF)” (step S102).

If the result of determination is that data has not been written (step S102 / YES), data is written to the head address of the data table 11 (step S10).
8) Write this write address at the top of the address table 12 (step S109). FIG. 4 shows an example of writing to the data management table 1 when the head data of the address table 12 has not been written in step S102.

When it is determined in step S102 that the head data of the address table 12 is data to which data has been written at least once (the address written at the head of the address table 12 is other than "FF") (step S102 / NO) ), Searching the address table 12 for the address of the most recently written data on the data table.

The search operation will be described below. The address on the address table 12 is incremented (step S103), the address data is sequentially read from the address table 12, and it is determined whether or not the read data is the last data in the address table (step S104). When it is determined that the read data is the last data of the address table 12 (step S104 / YES), the address table 12 cannot be written any more. Is stored, and the block is erased (step S105b).

If it is determined in step S104 that the read data is not the last data in the address table 12 (step S104 / NO), it is determined whether the read data is unwritten data (step S104). S105). When it is determined that the data is not written (the read address data is other than “FF”) (step S105 / NO), the process returns to step S103, and when it is determined that the data is not written (step S1).
05 / YES), and proceeds to step S106.

In step S106, the address on the address table 12 that has been incremented up to the unwritten data is decremented by 1, the address data is read from the address table 12, and the data is read from the data table based on the read latest address data. read out.

Next, in order to write the latest data, the address of the data table 11 is added by this data size (here, one) (step S10).
7) Write data on the data table 11 (step S108). On the address table 12,
The address data added in the data table 11 is written on the address table 12 (step S10).
9). FIG. 5 shows an example of writing in steps S108 and S109.

The processing shown in the flowchart of FIG. 2 can be realized by recording an arithmetic circuit and its program on a recording medium.

[0027]

As is apparent from the above description, according to the present invention, by setting a data management table for each piece of data that may be rewritten, rewriting data to the flash memory can be stored for each data type. Enable stacking,
The number of times of erasing data on the flash memory can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a state in which writing to a flash memory is performed using a data management table according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating an operation of a data management method according to an embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of a data management table according to the embodiment of the present invention.

FIG. 4 is a diagram showing an example of data writing when head data of an address table is unwritten data.

FIG. 5 is a diagram illustrating an example of data writing when head data of an address table is data that has already been written;

FIG. 6 is a diagram showing an example of a conventional data management method on a flash memory.

[Explanation of symbols]

 1 data management table 11 data table 12 address table

Claims (8)

[Claims] 1. A data management table is provided for each type of data that can be rewritten. The data management table includes a data table for stacking write data and address data of the stacked data sequentially from a top address. Data management for a flash memory, wherein data to be newly written is written to a location of the data table corresponding to a location where address data is not written on the address table. method. 2. The data management of a flash memory according to claim 1, wherein when address data has been written to the end of the address table, an erasing operation of a block including the data management table is performed. method. 3. A data management method for the flash memory, comprising: means for initializing an address of the data management table; reading head data of the data table; and determining whether the head data is "unwritten". Means for writing data to the head address of the data table if the result of the determination is "unwritten"; and address data for the written data on the data table. 3. A data management method for a flash memory according to claim 1, further comprising: means for writing to a start address of the flash memory. 4. When the result of the determination is that the head data is data that has been written at least once, the address data of the data written most recently on the data table is searched from the address table. Means for writing data to be newly written from the next address of the searched address data; and means for writing the newly written data on a location on the address table corresponding to a location on the data table. 4. A flash memory data management method according to claim 3, further comprising: means for writing address data of said newly written data on said data table. 5. A block including the data management table is erased when the address data of the data written most recently is searched on the address table and the address data is completely written on the address table. 5. The data management method for a flash memory according to claim 4, wherein the operation is performed. 6. A process for initializing an address of a data management table provided for each type of data that may be rewritten, and reading head data of a data table included in the data management table and stacking write data. A process of determining whether or not the head data is “unwritten”; and if the result of the determination is “unwritten”, a process of writing data to the head address of the data table; Writing the address data of the data on the data table to a head address of an address table that is included in the data management table and holds the address data of the data stacked in the data table sequentially from the head address. Recording medium on which a program for recording is recorded. 7. As a result of the determination, when it is determined that the head data is data that has been written once or more, the address table of the latest written data is searched from the address table in the data table. Processing for writing new data to be written from the next address of the searched address data; and writing the newly written data to a location on the address table corresponding to a location on the data table. 7. The recording medium according to claim 6, wherein a program for executing a process of writing address data of the newly written data on the data table is recorded. 8. When the address data of the most recently written data has been searched on the address table, if the address data has been written to the end on the address table, the block including the data management table is erased. 8. The recording medium according to claim 7, wherein a program for executing a process for performing an operation is recorded.