JP2008181381A - Semiconductor memory card, data management method for semiconductor memory card, database engine, and semiconductor memory system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor memory card, a data management method for a semiconductor memory card, and a database engine that enable efficient control of a nonvolatile semiconductor memory. <P>SOLUTION: The semiconductor memory card 1 comprises the database engine 100. The database engine 100 has an application interface part 101, a data management system part 102 and a file system part 103. The application interface part 101 converts a database query statement received from an application program 21 on a host device 2 into an internal format executable/interpretable in the database engine 100. The data management system part 102 adds, updates, deletes and otherwise manipulates various information about image files on a table 105 in a database 104. The file system part 103 controls the reading/writing of data stored in a NAND flash memory 12. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a semiconductor memory card that can be used by being attached to various electronic devices, a data management method for the semiconductor memory card, a database engine that performs data management for the semiconductor memory card, and a semiconductor memory system.

  Currently, a semiconductor memory card using a NAND flash memory is used as a recording medium for music data and video data. The NAND flash memory is characterized in that 1) data writing is performed in units of pages, and 2) data erasing is performed in units of blocks in which a plurality of pages are combined. For this reason, when data in a page included in a block having a written page is updated at random, a process called “moving writing” described below is performed. In moving writing, the data to be written (new data) is written to a new block where no data is written, and the remaining data that cannot be rewritten from the old block including the old data (data to be rewritten to the new data) to the new block. Copied.

  On the other hand, as a file system for managing data of a semiconductor memory card, a FAT (File Allocation Table) file system similar to a hard disk or the like is employed (see, for example, Patent Document 1).

  The FAT file system in the host device into which the semiconductor memory card is inserted divides a write file into data of a logical unit size called a cluster, searches for free clusters in the forward direction, and logically converts each divided data into logical data. Configure files by assigning addresses. The chain information indicating the order in which the clusters constituting the file are linked is written and managed as a table called FAT in a specific block inside the NAND flash memory. The semiconductor memory card is a logical-physical address correspondence table set in a specific block inside the NAND flash memory, showing the correspondence between the logical address of each data and the physical address indicating the physical location information inside the NAND flash memory. Write data while managing.

  When the FAT file file system as described above is used, the allocation of clusters constituting one file becomes discontinuous by repeatedly deleting and creating the file, and usually fits in one block inside the NAND flash memory. A file having a data size may be stored across two or more blocks.

Therefore, in the semiconductor memory card using both the FAT file file system and the NAND flash memory, there is usually a problem that the moving writing occurs frequently and the file writing and rewriting speed may be lowered.
JP 2001-188701 A

  The present invention provides a semiconductor memory card, a semiconductor memory card data management method, and a database engine capable of performing efficient control of a nonvolatile semiconductor memory.

  A semiconductor memory card according to an aspect of the present invention is a semiconductor memory card that can be detachably attached to a host device, and a nonvolatile semiconductor memory that can store data received from the host device, and an operation of the semiconductor memory card. A card controller for controlling, data received from the host device and file information stored in the nonvolatile semiconductor memory are managed by a database engine built in the card controller, and the database engine It operates by interpreting a database inquiry operation statement received from the apparatus.

  A data management method for a semiconductor memory card according to another aspect of the present invention includes a nonvolatile semiconductor memory that can store data received from a host device, data received from the host device, and data stored in the nonvolatile semiconductor memory. A data management method for a semiconductor memory card comprising a card controller for managing file information by a database engine, wherein an application interface unit included in the database engine interprets a database inquiry operation statement received from the host device. In accordance with the database query operation statement interpreted by the application interface unit, the data management system unit included in the database engine stores the file information stored in the nonvolatile semiconductor memory in the database. The file system unit included in the database engine writes the data received from the host device to the nonvolatile semiconductor memory and is stored in the nonvolatile semiconductor memory according to the instructions of the data management system unit. It controls the reading of data to the host device.

  The database engine according to yet another aspect of the present invention provides an application interface that interprets a database inquiry operation statement received from the host device in a semiconductor memory card having a nonvolatile semiconductor memory capable of storing data received from the host device. A data management system function for managing information on files stored in the nonvolatile semiconductor memory using a database in accordance with a database query operation statement interpreted by the function and the application interface function; and from the data management system function A file system function for controlling writing of data received from the host device to the nonvolatile semiconductor memory and reading of data stored in the nonvolatile semiconductor memory to the host device in accordance with instructions Characterized in that to realize.

  According to still another aspect of the present invention, there is provided a semiconductor memory system that can be attached to a host device. The semiconductor memory system includes a nonvolatile semiconductor memory that can store data received from the host device, and an operation of the semiconductor memory card. A card controller for controlling, data received from the host device and file information stored in the nonvolatile semiconductor memory are managed by a database engine built in the card controller, and the database engine It operates by interpreting a database inquiry operation statement received from the apparatus.

  The present invention can provide a semiconductor memory card, a data management method for a semiconductor memory card, a database engine, and a semiconductor memory system that can perform efficient control of a nonvolatile semiconductor memory.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram showing a relationship between a semiconductor memory card (hereinafter referred to as a memory card) 1 and a host device 2 according to the present embodiment. In the present embodiment, a digital still camera is assumed as the host device 2, and a memory card 1 is assumed to be a memory card dedicated to a digital still camera that manages information such as image file names and shooting dates / times in a database.

  The memory card 1 includes a card controller 11 that controls the operation of the memory card 1 and a non-volatile semiconductor memory that stores data (image file or the like) transmitted from the host device 2, for example, a NAND flash memory 12. Data received from the host device 2 and file information stored in the NAND flash memory 12 are managed by the database engine 100 incorporated in the card controller 11.

  The host device 2 includes an application program 21 that controls the memory card 1 using a database inquiry operation statement, and a liquid crystal display 22 that displays captured images and the like. The application program 21 has a function of processing information received from the memory card 1 into a form that can be easily recognized by the user and displaying the information on the liquid crystal display 22.

  As shown in FIG. 1, the host device 2 makes an inquiry to the memory card 1 by the application program 21, and the memory card 1 makes an answer to the host device 2 by the database engine 100 in response to an inquiry that requires an answer.

  Next, the hardware configuration inside the memory card 1 will be described. FIG. 2 is a block diagram showing a hardware configuration inside the memory card 1.

  As shown in FIG. 2, the card controller 11 includes a host interface unit 13, an MPU (Micro Processing Unit) 14, a memory interface unit 15, a ROM 16 (Read Only Memory), a RAM 17 (Random Access Memory), and a buffer 18.

  The host interface unit 13 performs interface processing between the card controller 11 and the host device 2, and the memory interface unit 15 performs interface processing between the card controller 11 and the NAND flash memory 12.

  The MPU 14 controls the operation of the card controller 11. For example, when the memory card 1 is supplied with power, the MPU 14 reads a control program stored in the ROM 16 onto the RAM 17 and executes predetermined processing.

  The ROM 16 stores a control program and the like controlled by the MPU 14, and the RAM 17 is used as a work area for the MPU 14.

  The buffer 18 temporarily stores a certain amount of data or sends data read from the NAND flash memory 12 to the host device 2 when writing data transmitted from the host device 2 to the NAND flash memory 12. In some cases, a certain amount of data is temporarily stored.

  In the NAND flash memory 12, the block at the time of erasure has 128 pages, for example, and has a data size of 256 kB (here, the capacity of the redundant portion is ignored). However, the present invention is not limited to this, and a NAND flash memory having a block size of 16 kB or the like can be used.

  The NAND flash memory 12 may be a binary memory that stores 1-bit information in one memory cell, or a multi-value memory that stores information of 2 bits or more in one memory cell. Also good. The NAND flash memory 12 and the card controller 11 may be provided individually on the substrate or may be disposed on the same LSI substrate.

  In the present embodiment, the MPU 14 reads the database engine 100 stored as a program in the ROM 16 onto the RAM 17, and manages data received from the host device 2 and file information stored in the NAND flash memory 12.

  The hardware configuration inside the memory card 1 is not limited to the above configuration. Therefore, the recording medium in which the database engine 100 is stored is not limited to the ROM 16 as a matter of course.

  Next, the configuration of the database engine 100 that operates inside the memory card 1 will be described. FIG. 3 shows the relationship between the database engine 100 and data received from the host device 2 and file information stored in the NAND flash memory 12. The database engine 100 includes an application interface unit 101, a data management system unit 102, and a file system unit 103. Further, the NAND flash memory 12 stores a database file, an image file, and the like constituting a database 104 described later.

  The application interface unit 101 converts the database inquiry operation statement received from the application program 21 of the host device 2 into an internal format that can be executed and interpreted in the database engine 100. The database inquiry operation statement may use a language appropriately defined by an arbitrary character string or the like, and may be described in, for example, an SQL language. The SQL language is a language generally used for a database engine that manages a relational database, and is classified into a data definition language, a data operation language, and a data control language.

  The data management system unit 102 stores image files stored in the NAND flash memory 12 against the table 105 in the database 104 shown in FIG. 4 according to the database query operation statement converted into the internal format by the application interface unit 101. Add, update, and delete various information. As shown in FIG. 4, the database 104 includes a table 105 in which, for example, file names, shooting dates and times, and addresses indicating the storage positions of image files in the NAND flash memory 12 described later are set as items. The items in the table 105 need not be limited to the file name, shooting date and time, and address, and various information such as the file size and file attributes may be set in the items as necessary.

  Further, the data management system unit 102 instructs the file system unit 103 to update information in the database 104 stored in the NAND flash memory 12 and write / read image files to / from the NAND flash memory 12. .

  The database 104 includes a plurality of tables 105 in which arbitrary items are set, and these are associated with each other to constitute a relational database.

  The file system unit 103 writes data received from the host device 2 to the NAND flash memory 12 and reads data stored in the NAND flash memory 12 to the host device 2 in accordance with instructions from the data management system unit 102. Control. In addition, the file system unit 103 determines a data management size as a unit of file input / output, and manages the storage positions of the files and image files in the NAND flash memory 12 constituting the database 104.

  Next, the operation of the memory card 1 will be described.

  FIG. 5 shows a list read operation of the image file stored in the NAND flash memory 12. The database inquiry operation statement transmitted from the application program 21 of the host device 2 to the database engine 100 (not shown) of the memory card 1 includes an all file list read request. In FIG. 5, “RA” indicates an all file list read request.

  The application interface unit 101 in the database engine 100 converts the received database query operation statement into an internal format that can be interpreted by the database engine 100. The data management system unit 102 searches the file name and shooting date / time items from the table 105 in the database 104 according to the instruction converted into the internal format by the application interface unit 101, and sends the data from the database 104 to the file system unit 103. Instruct reading. The file system unit 103 reads data from the database 104 in the NAND flash memory 12 in accordance with an instruction from the data management system unit 102. The read data is transmitted to the application program 21 of the host device 2 as an answer including the entire file list.

  The application program 21 of the host device 2 processes the received all file list into a form that can be easily recognized by the user and displays it on the liquid crystal display 22. With the above operation, the user can check the information of the image file stored in the memory card 1.

  Next, an image file adding operation to the memory card 1 will be described with reference to FIG. When the user finishes photographing, the application program 21 requests selection of whether or not to save the photographed image. When the user selects save, an operation of adding an image file to the memory card 1 is executed. At this time, the database inquiry operation statement transmitted from the application program 21 to the database engine 100 (not shown) includes information regarding a data addition request, file name, shooting date and time, and additional image data.

  In FIG. 6, “W” indicates a data addition request, “00010.jpg” indicates a file name, “20060720151230” indicates a shooting date, and “image data A” indicates additional image data. The application interface unit 101 in the database engine 100 converts the database inquiry operation statement into an internal format that can be executed and interpreted within the database engine 100. The data management system unit 102 adds file information to the table 105 in the database 104 according to the information converted by the application interface unit 101, updates the database 104 in the NAND flash memory 12, and transfers it to the NAND flash memory 12. The file system unit 103 is instructed to write the image file.

  The file system unit 103 updates the database 104 in the NAND flash memory 12 and writes an image file to the NAND flash memory 12 in accordance with an instruction from the data management system unit 102. A method by which the file system unit 103 manages the storage position of data stored in the NAND flash memory 12 will be described later.

  Next, an image file reading operation from the memory card 1 will be described with reference to FIG. The user selects an image file to be displayed from the file list displayed on the liquid crystal display 22 by the all file list read operation statement. At this time, the database inquiry operation statement transmitted from the application program 21 to the database engine 100 (not shown) includes a read request and the file name of image data to be read.

  In FIG. 7, “R” indicates a read request, and “00009.jpg” indicates a file name to be read. The application interface unit 101 converts the database inquiry operation statement into an internal format that can be executed and interpreted within the database engine 100. The data management system unit 102 searches the table 105 in the database 104 according to the information converted by the application interface unit 101.

  The data management system unit 102 searches the table 105 for a line having a matching file name, and refers to the corresponding address to instruct the file system unit 103 to read the image file from the NAND flash memory 12. The file system unit 103 reads an image file in accordance with an instruction from the data management system unit 102. The read image file is transmitted to the application program 21 as an answer. The application program 21 processes the received information into a form that can be easily recognized by the user and displays it on the liquid crystal display 22.

  Next, the image file deletion operation from the memory card 1 will be described with reference to FIG. The user selects an image file to be deleted from the file list displayed on the liquid crystal display 22 by the all file list read operation statement. At this time, the database inquiry operation statement transmitted from the application program 21 to the database engine 100 (not shown) includes a deletion request and the file name of the image data to be deleted.

  In FIG. 8, “D” indicates a deletion request, and “00008.jpg” indicates a file name to be deleted. The application interface unit 101 converts this database inquiry operation statement into an internal format. The data management system unit 102 searches the table 105 in the database 104 according to the information converted by the application interface unit 101. The data management system unit 102 searches the table 105 for a line having a matching file name, and refers to the corresponding address to instruct the file system unit 103 to delete the image file from the NAND flash memory 12. The file system unit 103 deletes the image file in accordance with an instruction from the data management system unit 102.

  Next, a method for managing the storage location of data stored in the NAND flash memory 12 by the file system unit 103 will be described. The file system unit 103 manages the storage area of the NAND flash memory 12 with a recording unit RU having a size that is 1/4 times the size of the block BK that is an erasable unit, that is, a size of 64 kB. That is, the file system unit 103 divides the file into data having the size of the recording unit RU and writes the data. The size of the recording unit RU is not limited to ¼ times the size of the block BK, and may be 1 / n (n is an even number) times the size of the block BK.

  Hereinafter, management of the data storage position of the image file will be described. Various files that make up the database 104 are managed in the same way, and are therefore omitted. First, consider a case where the image file A, the image file B, the image file C, and the image file D are written to the NAND flash memory 12. The image file A is for three recording units RU, the image file B is for two recording units RU, the image file C is for two recording units RU, and the image file D is for one recording unit RU, each of which is one block. Suppose that it fits in BK.

  As shown in FIG. 9, when writing these files to the NAND flash memory 12, the file system unit 103 divides each file into the size of the recording unit RU, and divides each divided data at the head of the vacant block BK. Will continue to place. As described above, data is written so that a file having a size equal to or smaller than the size of the block BK is not arranged across the plurality of blocks BK.

  Next, consider a case where writing of a file E having a size that does not fit in one block BK occurs. File E is the size of nine recording units RU. First, when a continuous free area for nine recording units RU can be secured in the storage area of the NAND flash memory 12, each divided data is arranged in that area.

  On the other hand, when a continuous area for 9 recording units RU cannot be secured in the storage area of the NAND flash memory 12, the data constituting the image file A to the image file D is rearranged in consideration of the file sizes, and is free. Data constituting the file E is continuously written in the resulting block.

  Thus, the file system unit 103 controls writing so that the data divided into the size of the recording unit RU constituting one file is not arranged across a plurality of non-consecutive blocks BK. Compared to the prior art, the number of blocks BK that must be accessed during file rewriting is reduced, and the efficiency during rewriting is improved.

  As described above, in the memory card 1 according to the present embodiment, since the database engine 100 is incorporated in the card controller 11, it is not necessary for the host device 2 to implement a file system, and simple definition statements can be made using database inquiry operation statements. It is possible to access the memory card 1 simply by giving an operation statement, and an image file stored in the NAND flash memory 12 can be searched efficiently.

  Further, since the database engine 100 has a unique file system unit 103, it is not necessary to use the FAT file system which has been used for controlling the semiconductor memory card by the host device in the past, and the NAND flash memory 12 as described above. It is possible to perform control suitable for the characteristics of the data and realize high-speed data rewriting.

  Since the database engine 100 has its own file system unit 103, for example, even if the specification of the NAND flash memory built in the semiconductor memory card changes, the NAND flash memory can be used without affecting the host device. A suitable control method can be employed.

  In addition, complicated functions for making use of the FAT file system conventionally used in the semiconductor memory card become unnecessary.

  The data writing method to the NAND flash memory 12 is not limited to the method described in the present embodiment, and is a method in which data is sequentially written sequentially from the first page to consecutive pages in the same block BK. It is possible to design a file system as appropriate.

  In the memory card 1 according to the present embodiment, the database engine 100 has the file system unit 103. However, the present invention is not limited to this, and the database engine 100 may directly control the NAND flash memory 12 as a raw device. good.

  In the memory card 1 according to the present embodiment, the database 104 is a relational database. However, the present invention is not limited to this, and other types of databases such as a hierarchical type and a network type may be used.

  In the memory card 1 according to the present embodiment, the case where the image data is not included in the database 104 has been described. However, the present invention is not limited to this, and the database engine 100 may be designed to manage the image data inside the database 104. good.

  Further, it is possible to add improvements such as reading out thumbnail images of corresponding image data and displaying them on the liquid crystal display 22 at the time of reading all file lists.

  Further, an improvement such as an enhancement of the security function may be added by setting an access right for the database 104 or mounting an encryption engine inside the database engine 100.

  In addition to a search specifying a file name, functions such as a search specifying a shooting date range, a search specifying a date, and the like may be added as appropriate.

  Further, in the memory card 1 according to the present embodiment, the semiconductor memory card having the NAND flash memory has been described. However, the present invention is not limited to this, and the semiconductor memory having a nonvolatile semiconductor memory such as an AND flash memory or a NOR flash memory. The present invention can also be applied to cards. In this case, a database engine suitable for the characteristics of each memory may be incorporated in the semiconductor memory card.

  In the memory card 1 according to the present embodiment, the operation when used with a digital still camera has been described. However, for other electronic devices such as a music player, a small laptop computer, a PDA, and a mobile phone. Can also be used. In this case, a database engine corresponding to each application may be incorporated in the semiconductor memory card.

  Further, the present invention is not limited to the case where the memory card 1 having the card controller 11 incorporating the database engine 100 and the NAND flash memory 12 controlled by the card controller 11 is used in various electronic devices. When the capacity is further increased, the semiconductor memory system having the card controller 11 and the NAND flash memory 12 can be directly incorporated into various electronic devices.

1 is a schematic diagram showing a configuration of a semiconductor memory card and a host device according to an embodiment of the present invention. 1 is a block diagram showing a hardware configuration of a semiconductor memory card according to an embodiment of the present invention. The block diagram which shows the structure of the database engine of the semiconductor memory card based on embodiment of this invention. Schematic which shows the table used for the file information management of the semiconductor memory card based on embodiment of this invention. The conceptual diagram which shows the file list read-out operation | movement of the semiconductor memory card based on embodiment of this invention. The conceptual diagram which shows the data write-in operation | movement of the semiconductor memory card based on embodiment of this invention. The conceptual diagram which shows the data read-out operation | movement of the semiconductor memory card based on embodiment of this invention. The conceptual diagram which shows the data deletion operation | movement of the semiconductor memory card based on embodiment of this invention. The conceptual diagram explaining the management method of the data storage position of the semiconductor memory card based on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor memory card 2 Host apparatus 11 Card controller 12 NAND flash memory 13 Host interface part 14 MPU
15 Memory interface 16 ROM
17 RAM
18 buffer 21 application program 22 liquid crystal display 100 database engine 101 application interface unit 102 data management system unit 103 file system unit 104 database 105 table BK block RU recording unit

Claims (7)

In a semiconductor memory card that can be detachably attached to a host device,
A nonvolatile semiconductor memory capable of storing data received from the host device;
A card controller for controlling the operation of the semiconductor memory card,
Data received from the host device and file information stored in the nonvolatile semiconductor memory are managed by a database engine incorporated in the card controller, and the database engine stores a database inquiry operation statement received from the host device. A semiconductor memory card which operates by being interpreted. The database engine is
An application interface unit for interpreting a database query operation statement received from the host device;
A data management system unit for managing file information stored in the nonvolatile semiconductor memory using a database;
And a file system unit that controls writing of data received from the host device to the nonvolatile semiconductor memory and reading of data stored in the nonvolatile semiconductor memory to the host device. Item 14. A semiconductor memory card according to Item 1.   The semiconductor memory card according to claim 1, wherein the nonvolatile semiconductor memory is a NAND flash memory.   4. The semiconductor memory card according to claim 1, wherein the database inquiry operation statement is described in an SQL language. A semiconductor memory comprising: a nonvolatile semiconductor memory capable of storing data received from a host device; and a card controller for managing data received from the host device and file information stored in the nonvolatile semiconductor memory by a database engine A card data management method,
The application interface unit of the database engine interprets a database inquiry operation statement received from the host device,
In accordance with the database query operation statement interpreted by the application interface unit, the data management system unit of the database engine manages information on files stored in the nonvolatile semiconductor memory using a database,
In accordance with an instruction from the data management system unit, the file system unit of the database engine writes the data received from the host device into the nonvolatile semiconductor memory and the host device stores data stored in the nonvolatile semiconductor memory A data management method for a semiconductor memory card, characterized by controlling reading to the memory. In a semiconductor memory card having a nonvolatile semiconductor memory capable of storing data received from the host device,
An application interface function for interpreting a database query operation statement received from the host device;
A data management system function for managing file information stored in the nonvolatile semiconductor memory using a database according to a database inquiry operation statement interpreted by the application interface function;
A file system function for controlling writing of data received from the host device to the nonvolatile semiconductor memory and reading of data stored in the nonvolatile semiconductor memory to the host device in accordance with an instruction from the data management system function A database engine characterized by realizing In a semiconductor memory system that can be attached to a host device,
A nonvolatile semiconductor memory capable of storing data received from the host device;
A card controller for controlling the operation of the semiconductor memory card,
Data received from the host device and file information stored in the nonvolatile semiconductor memory are managed by a database engine incorporated in the card controller, and the database engine stores a database inquiry operation statement received from the host device. A semiconductor memory system which operates by interpretation.

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