JP2008152415A - Access device, memory controller, non-volatile memory device, and non-volatile memory system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that an actually available capacity is reduced due to the frequent rewriting of file system management information in pseudo overwrite to a non-volatile memory device equipped with an OTP memory by using address conversion. <P>SOLUTION: Before file data are written from an access device in a non-volatile memory device, write start position information is notified, and file system management information is written. After the write of the file data is completed, the file system management information is rewritten according to the quantity of the written file data, and write completion information is notified. Also, the access device acquires information showing whether or not write has been normally ended from the non-volatile memory device, and acquires write end position information and the previously stored write start position information when the write has been abnormally ended, and rewrites the file system management information according to the quantity of the written file data. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an access device, a memory controller, a nonvolatile storage device, and a nonvolatile storage system relating to a method for an access device to write to a nonvolatile storage device through a file system.

  In recent years, there are various types of storage devices that store music content and digital data such as video data, such as magnetic disks, optical disks, and magneto-optical disks. Memory cards, which are one type of these storage devices, mainly use non-volatile memories such as flash memories as storage elements and can be miniaturized, so that they can be miniaturized in digital still cameras, mobile phone terminals, video cameras, etc. It is spreading rapidly, especially in mobile devices.

  The data stored in the memory card is managed by a file system, and the user can easily handle the stored data as a file. Conventionally used file systems include a FAT file system (see Non-Patent Document 1), a UDF file system (Universal Disk Format) (see Non-Patent Document 2), an NTFS file system (New Technology File System), and the like. . Since memory cards in which data is managed by these file systems can share files between devices that interpret the same file system, data can be exchanged between devices.

  Further, the FAT file system uses a file allocation table (hereinafter referred to as FAT) to manage content such as moving images as file data for each fixed-length block unit of about 16 KB or 32 KB called a cluster. The file size, file name, and the like are managed by information called a directory entry. That is, it is not established as a file just by writing file data to the nonvolatile storage device, but it is established as a file only when file system management information such as FAT and directory entry is written together in the nonvolatile storage device. In conventional video cameras, the file system management information is frequently rewritten to establish the written video data as a file, and even when the power is shut off due to unexpected battery removal due to device dropping, etc. Measures are taken so that the moving image data written just before is left in the nonvolatile storage device.

  On the other hand, recently, an OTP (One Time Programmable) memory that can be manufactured at a low cost by applying the technology of a conventional CMOS process has been attracting attention as a recording element different from a NAND flash memory. Although the OTP memory has a limitation that it can be written only once in the same physical memory area, it is low in manufacturing cost, so it is used for applications such as long-term storage of data, especially like media such as DVD-R. There is a possibility of spreading as a memory card recording element. That is, it is sold as a relatively expensive memory card using a NAND flash memory for applications that require rewriting multiple times such as a conventional memory card, and rewriting is unnecessary after writing once. By selling it as a relatively inexpensive memory card using an OTP memory, it can be used properly according to user needs.

  Further, as a method for realizing rewriting of the above-described file system management information using an OTP memory that can be written only once, there is a method realized by address conversion. This applies the conversion function of the logical address and physical address that has been used as a replacement method of the defective block in the past, and data overwriting occurred in a part of the area reserved for replacement of the defective block. A new allocation is performed at the time, and the data recording position is changed by address conversion, thereby realizing a pseudo overwrite on the OTP memory.

  However, when a memory card using this OTP memory is used in a device that frequently rewrites file system management information, such as a conventional video camera, pseudo-overwriting frequently occurs and it is unused. There is a problem that the physical area is consumed and the memory capacity that can be actually recorded decreases.

Conventionally, OTP memory and non-volatile memory that can be rewritten multiple times (hereinafter referred to as “flash memory”) are installed to manage this problem, and file system management information that is frequently rewritten is managed on the flash memory. A method for preventing the memory capacity of the memory from being reduced has been proposed (see Patent Document 1).
JP 2002-116942 A ISO / IEC9293, “Information Technology-Volume and file structure of disk cartridges for information”, 1994 OSTA Universal Disk Format Specification Revision 1.50, 1997

  However, the memory device in which the conventional OTP memory and the flash memory are mixed is cheaper than the memory device having only the conventional flash memory, but stores all the frequently rewritten portions such as file system management information. Therefore, it is necessary to mount a relatively large flash memory, and there is a problem that the price of the entire memory device cannot be reduced sufficiently.

  In recent years, the number of rewritable times has decreased with the increase in capacity and miniaturization of flash memory, and file system management information can be rewritten even in a memory device using only conventional flash memory without using OTP memory. In the conventional method that is frequently performed, there arises a problem that the lifetime of the memory device is shortened.

  The present invention solves such a conventional problem, and prevents the memory capacity of the OTP memory from being reduced even when writing file data to a non-volatile storage device not equipped with a flash memory, and Providing a nonvolatile storage device and access device to prevent the stored file data from being lost even if the power is turned off halfway due to an unexpected cause, and also providing a nonvolatile storage system that combines them It is intended to do.

  Also provided are a nonvolatile memory device and an access device for preventing the lifetime of the nonvolatile memory device from being shortened due to a decrease in the number of times the flash memory can be rewritten, and the access device and the nonvolatile memory device. An object of the present invention is to provide a non-volatile storage system combining the above.

  In order to solve the above problems, an access device according to the present invention is an access device connected to a nonvolatile storage device having a nonvolatile memory, and manages file data to be read from and written to the nonvolatile storage device by a file system. A file system control unit that performs writing, file system management information that is written to the nonvolatile storage device before writing the file data, and a file system that is in accordance with the amount of the file data that has been written. And an FS management information determination unit that rewrites the management information.

  The access device rewrites the file system management information when the amount of file data to be written becomes larger than the file size written in the file system management information written in advance by the FS management information securing unit. It is preferable to further include an FS management information expansion unit to be performed.

  In addition, the access device notifies the nonvolatile storage device of the write start position information before writing the file data, and notifies the write completion information after the writing of the file data is completed. And issuing a control signal to the non-volatile storage device to obtain the write status information, the write end position information of the file data, and the write start position information notified before writing the file data It is preferable to further include an FS management information receiving unit.

  More preferably, the nonvolatile memory may be a flash memory that can be rewritten a plurality of times or an OTP (One Time Programmable) memory that can be written only once.

  An access device according to the present invention is an access device connected to a non-volatile storage device having a non-volatile memory, and a file system control unit that manages file data to be read from and written to the non-volatile storage device by a file system, and a write An FS management information determination unit that rewrites file system management information in accordance with the amount of the file data that has been performed, and notifies the nonvolatile storage device of write start position information before writing the file data. An FS management information notifying unit for notifying write completion information after data writing is completed, a control signal is issued to the nonvolatile storage device, write status information, write end position information of the file data, and the file data The writing start position information notified before writing , And the FS management information receiving unit that acquires characterized by comprising a.

  The present invention is also a memory controller that is connected to a non-volatile memory and controls the non-volatile memory in response to an external access, and receives the write start position information and the write completion information notified from the outside. , An FS notification information processing unit that performs processing to be recorded in the non-volatile memory, and determines the status of the writing process in response to the control signal from the outside, and the writing status information and the writing end position of the file data according to the determination And a previous process determination unit for notifying the write start position information that has been notified before writing the information and the file data.

  A non-volatile storage device according to the present invention is a non-volatile storage device having a non-volatile memory, and is equipped with a memory controller that controls the non-volatile memory in response to an external access, and the memory controller is notified from the outside. FS notification information processing unit that receives the write start position information and the write completion information to be recorded and records the information in the nonvolatile memory, and determines the status of the write process in response to the external control signal, and the determination And a previous process determination unit for notifying the write start position information that has been notified before writing the file data.

  A non-volatile storage system according to the present invention is a non-volatile storage system having a non-volatile storage device having a non-volatile memory, and an access device connected to the non-volatile storage device for access, wherein the access device is A file system control unit that manages file data to be read from and written to the nonvolatile storage device by a file system, and an FS management information securing unit that writes file system management information to the nonvolatile storage device before writing the file data And an FS management information determination unit that rewrites the file system management information in accordance with the amount of the file data that has been written.

  In the non-volatile storage system according to the present invention, the non-volatile storage device receives the write start position information and the write completion information notified from the access device and performs a process of recording the information in the non-volatile memory. And a control signal from the access device to determine the status of the write process, and according to the determination, the write status information, the write end position information of the file data, and the file data that was notified before writing And a previous process determination unit for notifying write start position information.

  According to the nonvolatile storage system of the present invention, when the access device writes file data to the nonvolatile storage device having the nonvolatile memory, the number of times of rewriting the file system management information can be reduced. As a result, when the nonvolatile memory is an OTP memory, it is possible to prevent the memory capacity from being reduced. When the nonvolatile memory is a flash memory, an effect of extending the life can be obtained. Furthermore, since the number of times of rewriting the file system management information is reduced, file data can be written continuously, and the writing time can be shortened.

  In addition, even when the power is turned off halfway due to an unexpected cause while writing file data to the nonvolatile storage device, the access status information, write start position information, and write end position information are accessed. Is obtained from the nonvolatile storage device and the file system management information is restored, so that the file data stored until immediately before the power is turned off can be prevented from being lost.

(Embodiment 1)
Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a nonvolatile memory system according to an embodiment of the present invention. In FIG. 1, the nonvolatile storage system includes an access device 1 and a nonvolatile storage device 2. The access device 1 includes a CPU 11, a RAM 12, a slot 13, and a control unit 14. The control unit 14 stores a program and a control circuit for controlling the access device 1, and the program and the control circuit operate on the CPU 11 using the RAM 12 as a temporary storage area. The slot 13 is a connection unit that connects the nonvolatile storage device 2 and the access device 1, and control signals, file data, and various information are transmitted and received between the access device 1 and the nonvolatile storage device 2 via the slot 13. Is done. The control unit 14 further includes an application program 15, a file system control unit 16, an access control unit 17, an FS management information securing unit 18, an FS management information determination unit 19, an FS management information expansion unit 20, an FS management information notification unit 21, and an FS. A management information receiving unit 22 is included.

  The application program 15 is a program or a control circuit that controls an application that operates on the access device 1. For example, in the case of a video camera, a video shooting program or the like is included.

  The file system control unit 16 provides a file system function that manages writing and reading of file data to and from the nonvolatile storage device 2 in units of files. In the present embodiment, a FAT file system is assumed as a file system controlled by the file system control unit 16.

  The access control unit 17 has a function of designating a processing start logical address and a processing size for the logical address space constructed on the non-volatile storage device 2, and writing and reading file system management information and file data. provide.

  The FS management information securing unit 18 provides a function of writing file system management information to the nonvolatile storage device 2 before writing file data.

  The FS management information determination unit 19 provides a function of rewriting file system management information in accordance with the amount of file data that has been written.

  The FS management information expansion unit 20 rewrites the file system management information when the amount of file data to be written becomes larger than the file size stored in the file system management information written in advance by the FS management information securing unit 18. Provide functionality.

  The FS management information notification unit 21 provides a function of notifying the nonvolatile storage device 2 of the write start position information before writing the file data and notifying the write completion information after the writing of the file data is completed.

  The FS management information receiving unit 22 issues a control signal to the nonvolatile storage device 2 to acquire the write status information, the write end position information of the file data, and the write start position information notified before writing the file data. Provide functionality.

  On the other hand, in FIG. 1, the nonvolatile memory device 2 includes a memory controller 25 and a nonvolatile memory 27. The memory controller 25 includes a host interface unit 250 (hereinafter referred to as a host I / F unit), an address management unit 251, a memory access unit 252, an FS notification information processing unit 253, and a previous process determination unit 254. .

  The host I / F unit 21 is an interface that transmits and receives control signals, file data, and various information to and from the access device 1.

  The address management unit 251 provides a function of converting file system management information, file data, and various types of information from the access device 1 from a specified logical address to a physical address of the mounted non-volatile memory 27. . In addition, when the nonvolatile memory 27 is an OTP memory that can be written only once, the function of managing the address of the OTP memory so that the file data can be written multiple times from the access device 1 to the same logical address. provide.

  The memory access unit 252 provides a function of performing physical read / write on the nonvolatile memory 27.

  The FS notification information processing unit 253 provides a function of receiving the write start position information and the write completion information notified from the access device 1 and recording the information in the nonvolatile memory 27.

  The previous process determination unit 254 determines the status of the write process in response to an external control signal, and notifies the write status information, the file data write end position information, and the file data before writing according to the determination. A function of notifying the access device 1 of write start position information is provided.

  The nonvolatile memory 27 is a storage area 271 that constitutes a logical address space for storing file data, file system management information, and the like, and information that manages the correspondence between the logical address and the physical address of the data stored in the storage area 271 And an address management information storage unit 272 for storing.

  The operation of the nonvolatile memory system configured as above according to Embodiment 1 of the present invention will be described. For the sake of simplicity, the file system control unit 16 of the access device 1 will be described as managing file data with the FAT file system.

  First, a description will be given with reference to the flowchart of FIG. 5 showing the processing procedure of the control unit 14 when the access device 1 writes file data to the nonvolatile storage device 2. In step S500, the file system control unit 16 reads the file system management information from the nonvolatile storage device 2, and searches for a free area (unused cluster) on the FAT.

  In step S510, the FS management information securing unit 18 writes the cluster chain that has been secured on the FAT as file system management information. Here, for the sake of simplicity, a chain of 1000 clusters is written in the nonvolatile storage device 2.

  Next, in step S520, the FS management information securing unit 18 stores the same starting cluster number as the chain for the cluster written in step S510 and the file size for 1000 clusters in the directory entry as non-volatile storage as file system management information. Write to device 2. As a result, the directory entry and FAT are in a state as shown in FIG. In the present embodiment, the file system management information means a cluster chain and directory entry on the FAT.

  Next, in step S530, the file data is written into the nonvolatile storage device 2 from the start cluster number designated in step S520.

  Next, in step S540, it is determined whether all file data writing processing from the access device 1 to the nonvolatile storage device 2 has been completed. As a result of the determination, if it is determined that the file data writing continues, the process proceeds to step S550. If it is determined that there is no file data to be written, the process proceeds to step S560.

  Step S550 is a process performed by the FS management information expansion unit 20, and compares and determines the size of the file size stored in the file system management information written by the FS management information securing unit 18 and the total amount of the written file data. In the present embodiment, the determination may be made based on whether or not file data for 1000 clusters has been written.

  As a result of the determination, if the file size is larger, the process proceeds to step S530 and the subsequent file data is written to the nonvolatile storage device 2. If it is determined in step S550 that the file size is smaller, the process proceeds to step S551, and the file system management information is rewritten so that larger file data can be written.

  In this embodiment, for example, FAT is written to the nonvolatile storage device 2 so that a chain of clusters on the FAT is connected so that another 1000 clusters can be written as file data, and the file size of the directory entry is further set to 2000 clusters. What is necessary is just to write to the non-volatile storage device 2 by changing to As a result, the state of FIG. 11 changes to the state of the directory entry and FAT of FIG.

  Step S560 is a process performed by the FS management information determination unit 19 for an area in which the chain of clusters on the FAT of the file system management information is not written according to the amount of file data written by the access device 1 in step S530. And rewrite it to be an unused cluster.

  Next, in step S570, in the directory entry of the file system management information with respect to the nonvolatile storage device 2, according to the amount of file data written in step S530 by the FS management information determination unit 19 in the same manner as step S560. Rewrite a file size to an accurate value. For example, if a chain for 1000 clusters has been written on the FAT in advance, and the amount of file data written by the access device 1 is 17000 bytes, the state of FIG. 11 is obtained by the processing in steps S560 and S570. Is rewritten to the state of FIG.

  By doing so, it is possible to reduce the number of times the file system management information is rewritten when writing the file data written by the access device 1 to a nonvolatile storage device equipped with a nonvolatile memory. When the nonvolatile memory is an OTP memory, it is possible to prevent the memory capacity from being reduced. In addition, when the nonvolatile memory is a flash memory, the life can be extended. In addition, since the number of times of rewriting the file system management information is reduced, file data can be written continuously, so that the effect of shortening the writing time can also be obtained.

  Furthermore, even if the power is turned off during file data recording due to an unexpected cause, the file data already stored in the nonvolatile storage device can be prevented from being lost.

  Although the present invention has been described based on the above embodiment, it is needless to say that the present invention is not limited to the above embodiment. Various modifications can be made without departing from the spirit of the present invention. The numerical values used in the present embodiment are examples, and other numerical values may be used. For example, the example of securing the FAT chain in units of 1000 clusters in the flowchart of FIG. 5 has been described, but the FAT chain may be secured in other units such as 100 clusters.

  The non-volatile storage device 2 connected to the access device 1 may be a conventional non-volatile storage device having a non-volatile memory that can be rewritten a plurality of times, and functions of the FS notification information processing unit 253 and the previous process determination unit 254. It is not necessary to have.

(Embodiment 2)
In the nonvolatile storage system according to the first embodiment, when file power is being written to the nonvolatile storage device 2 and the power is turned off halfway due to an unexpected cause, a chain of clusters on the FAT, Since the file size of the directory entry is different from the amount of file data actually written, the file data is correct until the power is turned off, but the file data is not relevant from the middle of the file data. Is read out to the access device 1. Therefore, a second embodiment that addresses this problem will be described. The block diagram of the nonvolatile memory system according to the second embodiment is the same as that shown in FIG. Here, a processing procedure of the control unit 14 when the access device 1 writes file data to the nonvolatile storage device 2 and a processing procedure of the control unit 14 performed after the power is turned on will be described.

[Process when writing]
First, the processing procedure of the control unit 14 when writing file data will be described with reference to the flowchart of FIG. In step S500, a free area (unused cluster) is searched on the FAT of the nonvolatile storage device 2.

  Next, in step S610, the FS management information notification unit 21 notifies the nonvolatile storage device of the write start position information and stores the information in the nonvolatile storage device 2. Here, as the write start position information, for example, a logical address for writing a directory entry and a logical address for starting writing file data are used. Next, the process proceeds to step S510, and subsequent steps S510 to S570 are the same as those in the first embodiment. After executing Step S570, the process proceeds to Step S620.

  Step S620 is a process performed by the FS management information notification unit 21 to notify the nonvolatile storage device 2 of the write completion information and store it in the nonvolatile storage device 2.

[Process after turning on the power]
Next, the processing procedure of the control unit 14 performed after the power is turned on will be described with reference to the flowchart of FIG. Note that the processing described here is processing performed after the power is turned on, but description will be made assuming that processing such as initialization for the access device 1 to access the nonvolatile storage device 2 has been completed.

  Step S910 is a process performed by the FS management information receiving unit 22, in which the FS management information notification unit 21 issues a control signal to the nonvolatile storage device 2 and writes the write status information, the write end position information, and the file data. Acquire the notified write start position information.

  Here, the write start position information includes, for example, a logical address for writing a directory entry and a logical address for starting writing file data.

  Step S920 is a process performed by the FS management information receiving unit 22 to determine write status information and determine whether the previous write process has been performed normally. If it is determined that the previous writing process has been performed normally, the process ends. If it is determined that the previous writing process was abnormal, the process proceeds to step S930.

  Step S930 is processing performed by the FS management information determination unit 19 to calculate the amount of file data written based on the write end position information and the write start position information, and on the FAT of the file system management information according to the amount. Rewrite the existing cluster chain so that the area without file data becomes an unused cluster.

  In the next step S940, the file size in the directory entry of the file system management information is accurately set for the nonvolatile storage device 2 according to the amount of file data calculated in the same manner as in step S930 by the FS management information determination unit 19. Rewrite to a correct value. As a result, if the power is turned off halfway due to an unexpected cause during writing, and the amount of file data actually written does not match the FAT / directory entry, After startup, it is possible to restore the FAT / directory entry with the correct size.

  Step S950, which is the next process, is a process performed by the FS management information notification unit 21, and notifies the nonvolatile storage device 2 of the write completion information and stores it in the nonvolatile storage device 2.

  On the other hand, processing contents of the memory controller 25 of the nonvolatile memory device 2 in the nonvolatile memory system according to Embodiment 2 of the present invention will be described below with reference to FIGS.

  In step S500, step S510, step S520, step S530, step S551, step S560, step S570, step S930, and step S940, the address management unit 251 receives the file system management information, file data, and various information from the access device 1. The logical address designated for reading / writing is converted into the physical address of the mounted nonvolatile memory 27, and physical reading / writing to the nonvolatile memory 27 is performed through the memory access unit 252.

  Steps S610, S620, and S950 are processes performed by the FS notification information processing unit 253. The write start position information and the write completion information notified from the access device 1 are received, and the address management unit 251 and the memory access unit 252 are connected. A process of recording in the nonvolatile memory 27 is performed while controlling.

  Step S910 is a process performed by the previous process determination unit 254. The previous process determination unit 254 receives the control signal from the access device 1, accesses the nonvolatile memory 27 while controlling the address management unit 251 and the memory access unit 252, and reads the stored write start position information. In addition, in order to determine whether or not the previous writing has been performed normally, it is determined whether or not writing completion information that is paired with the writing start position information is stored. Write status information indicating that the write processing is normal, and writing status information indicating that the previous write processing is abnormal is generated when paired write completion information is not stored. Further, the write end position information of the file data written last is read. Then, the access device 1 is notified of these write start position information, write status information, and write end position information. Here, the write end position information means information indicating how far the nonvolatile storage device 2 has been written. For example, the last written logical address is used.

  Next, an example of a method for storing the write start position information, write completion information, file data, FAT as file system management information, and directory entry in the nonvolatile memory 27 according to the second embodiment will be described with reference to FIG. explain.

  The nonvolatile memory 27 has a logical address space and a physical address space, and can be converted from a logical address to a physical address by an address management unit. The physical address space includes a storage area 271 and an address management information storage unit 272. The recording area 271 stores write start position information, write completion information, file data, FAT, and directory entry information itself. The address management information storage unit 272 stores logical addresses designated from the outside when writing FAT, directory entry, and file data, and assigns and stores IDs indicating write start position information and write completion information. For example, the IDs of the write start position information and the write completion information are KXX, and XX is the number of times the write start position information has been notified. In the example of FIG. FAT, directory entry, and file data are written as AXXX, and XXX stores a logical address designated from the outside. In addition, if writing rules such as writing from an unused area of a lower physical address are defined as writing to the physical address space, even if the address management information storage unit 272 includes the same logical address, It can be determined that the latest data is stored at the upper physical address. In this way, the memory controller 25 can easily grasp where the FAT, directory entry, file data, unused area, etc. exist in the logical address space. Further, whether or not the writing has been normally performed can be easily grasped by determining whether or not the ID of the writing completion information that is paired with the ID of the writing start position information exists.

  As described above, as an effect, the number of rewrites of the file system management information when writing the file data written by the access device 1 to the nonvolatile storage device 2 equipped with the nonvolatile memory 27 is reduced. In the case where the nonvolatile memory 27 is an OTP memory, it is possible to prevent the memory capacity from being reduced. Further, when the nonvolatile memory 27 is a flash memory, an effect of extending the life can be obtained. In addition, if the power is turned off halfway due to an unexpected cause while writing file data to the nonvolatile storage device 2, the file size of the cluster chain and directory entry on the FAT is actually written. Since the state different from the amount of the file data is resolved and the correct size is obtained, irrelevant file data is not read to the access device 1 from the middle of the file data, and the memory capacity is further increased than in the first embodiment. The effect of preventing loss of eyes can be obtained. Further, since the number of times the file system management information is rewritten is reduced, file data can be written continuously, and an effect of shortening the time for writing can be obtained.

  In the second embodiment of the present invention, the case where the write start position information and the write completion information are stored in the storage area 271 has been described. Needless to say, an effect can be obtained.

(Embodiment 3)
Embodiment 3 in which the same effect as that of the nonvolatile memory system of Embodiment 2 can be obtained will be described. Note that the block diagram of the nonvolatile memory system according to Embodiment 3 is the same as that shown in FIG. Here, a processing procedure of the control unit 14 when the access device 1 writes file data to the nonvolatile storage device 2 and a processing procedure of the control unit 14 performed after the power is turned on will be described.

[Process when writing]
First, the processing procedure of the control unit 14 when writing file data will be described with reference to the flowchart of FIG.

  In step S500, a free area (unused cluster) is searched on the FAT of the nonvolatile storage device 2.

  Next, in step S610, the FS management information notification unit 21 notifies the nonvolatile storage device of the write start position information and stores the information in the nonvolatile storage device 2. Here, as the write start position information, for example, a logical address at which a directory entry is written and a directory entry to be written are notified.

  Next, in step S530, the file data is written to the nonvolatile storage device 2 from the starting cluster number of the directory entry specified in step S610. In this case, in the nonvolatile storage device 2, only file data is written in a state where there is no directory entry or cluster chain on the FAT, and the directory entry and the FAT are in a state as shown in FIG.

  Next, in step S540, it is determined whether all file data writing processing from the access device 1 to the nonvolatile storage device 2 has been completed. If it is determined that there is no file data to be written, the process proceeds to step S560. If it is determined that the file data writing continues, the process proceeds to step S530, and the subsequent file data writing is performed. At this time, it is preferable to write subsequent file data to the cluster having the lowest logical address among the unused clusters determined to be free areas in step S500.

  Step S560 is a process performed by the FS management information determination unit 19 for an area in which the chain of clusters on the FAT of the file system management information is not written according to the amount of file data written by the access device 1 in step S530. And rewrite it to be a used cluster.

  Next, in step S570, in the directory entry of the file system management information with respect to the nonvolatile storage device 2, according to the amount of file data written in step S530 by the FS management information determination unit 19 as in step S560. Rewrite a file size to an accurate value.

  Next, step S620 is a process performed by the FS management information notification unit 21 to notify the nonvolatile storage device 2 of the write completion information and store it in the nonvolatile storage device 2.

[Process after turning on the power]
Next, the processing procedure of the control unit 14 performed after the power is turned on will be described below. The processing similar to the processing in FIG. 9 according to the second embodiment may be performed. However, with respect to the write end position information acquired in step S910 and the write start position information notified by the FS management information notification unit 21, for example, file data It is preferable that the logical address that has been normally written, the logical address to which the directory entry is written, and the directory entry itself that is scheduled to be written.

  On the other hand, the processing content of the memory controller 25 of the nonvolatile memory device 2 according to the third embodiment of the present invention may be the same as that performed by the nonvolatile memory device 2 according to the second embodiment. By doing the above, the same effect as Embodiment 2 is acquired.

(Embodiment 4)
Embodiment 4 in which the same effects as those of the nonvolatile storage systems of Embodiments 2 and 3 can be obtained will be described. Note that the block diagram of the nonvolatile memory system according to Embodiment 4 is the same as that shown in FIG. Here, a processing procedure of the control unit 14 when the access device 1 writes file data to the nonvolatile storage device 2 and a processing procedure of the control unit 14 performed after the power is turned on will be described.

[Process when writing]
First, the processing procedure of the control unit 14 when writing file data will be described with reference to the flowchart of FIG. In step S500, an empty area (unused cluster) on the FAT of the nonvolatile storage device 2 is searched.

  In step S800, a directory entry with a file size of 0 is written to create a file.

  In step S610, the FS management information notification unit 21 notifies the nonvolatile storage device 2 of the write start position information and stores it. Here, as the write start position information, for example, a logical address for writing a directory entry and a logical address for starting writing file data are used.

  Next, in step S530, the file data is written to the nonvolatile storage device 2 from the starting cluster number of the directory entry specified in step S610. In this case, the nonvolatile storage device 2 writes the file data in a state where there is no cluster chain on the FAT and there is a directory entry whose file size is 0, and the directory entry and the FAT are in the state as shown in FIG. It becomes.

  Next, in step S540, it is determined whether all file data writing processing from the access device 1 to the nonvolatile storage device 2 has been completed. If it is determined that there is no file data to be written, the process proceeds to step S560. If it is determined that the file data writing continues, the process proceeds to step S530 to continue writing the file data. At this time, it is preferable to write subsequent file data to the cluster having the lowest logical address among the unused clusters determined to be free areas in step S500.

  Step S560 is a process performed by the FS management information determination unit 19 for an area in which the chain of clusters on the FAT of the file system management information is not written according to the amount of file data written by the access device 1 in step S530. And rewrite it to be a used cluster.

  Next, in step S570, in the directory entry of the file system management information with respect to the nonvolatile storage device 2, according to the amount of file data written in step S530 by the FS management information determination unit 19 as in step S560. Rewrite a file size to an accurate value.

  Next, step S620 is a process performed by the FS management information notification unit 21 to notify the nonvolatile storage device 2 of the write completion information and store it in the nonvolatile storage device 2.

[Process after turning on the power]
Next, the processing procedure of the control unit 14 performed after the power is turned on will be described below. Processing similar to that of FIG. 9 in Embodiment 2 may be performed. However, the example of the cluster chain and directory entry on the FAT as shown in FIG. 14 rewritten in steps S930 and S940 is rewritten to the cluster chain and directory entry on the FAT of the correct size as shown in FIG. It becomes.

  On the other hand, the processing content of the memory controller 25 of the nonvolatile memory device 2 in the nonvolatile memory system according to the fourth embodiment of the present invention may be the same as that performed by the nonvolatile memory device 2 according to the second embodiment. By doing the above, the same effect as Embodiment 2 is acquired.

  In the present embodiment, the process after the power is turned on is described. However, this process is not limited to the process after the power is turned on, and the previous writing is normally performed in the nonvolatile storage system. It only has to be done when it is necessary to confirm that it has been received, and there is no meaning in exactly determining when to do it.

  Although the present invention has been described based on the above embodiment, it is needless to say that the present invention is not limited to the above embodiment. Embodiments can be changed without departing from the spirit of the present invention. The numerical values used in the present embodiment are examples, and other numerical values may be used.

  The non-volatile storage system according to the present invention can prevent the memory capacity of the non-volatile storage device from being reduced due to pseudo-overwrite processing on the OTP memory when the OTP memory is used, and can be rewritten multiple times. In the case of using a non-volatile memory, a method capable of extending the rewrite life is proposed. Such a non-volatile storage device is useful as a recording medium for a still image recording / reproducing device, a moving image recording / reproducing device, or a mobile phone.

The block diagram which shows the non-volatile storage system in the embodiment of this invention Explanatory drawing which showed the structure of the FAT file system in embodiment of this invention Explanatory drawing which showed the structure of the directory entry of FAT file system in embodiment of this invention An example of a method for storing data in a nonvolatile memory according to an embodiment of the present invention The flowchart which showed the file data write-in processing procedure of the access apparatus 1 in Embodiment 1 of this invention The flowchart which showed the file data write-in processing procedure of the access apparatus 1 in Embodiment 2 of this invention. The flowchart which showed the file data write-in processing procedure of the access apparatus 1 in Embodiment 3 of this invention. The flowchart which showed the file data write-in processing procedure of the access apparatus 1 in Embodiment 4 of this invention. The flowchart which showed the process sequence after the power supply in embodiment of this invention was turned on Explanatory drawing which showed an example of the directory entry and FAT after writing in embodiment of this invention Explanatory diagram showing an example of directory entry and FAT after the FS management information securing unit 18 has previously written a chain and directory entry for 1000 clusters in the first embodiment of the present invention. Explanatory drawing which shows an example of the directory entry and FAT after the FS management information expansion part 20 in Embodiment 1 of this invention rewrites for 2000 clusters Explanatory drawing which shows an example of the directory entry and FAT which are writing the file data in Embodiment 3 of this invention Explanatory drawing showing an example of directory entry and FAT during writing of file data in Embodiment 4 of the present invention

Explanation of symbols

1 Access device 2 Non-volatile storage device 11 CPU
12 RAM
DESCRIPTION OF SYMBOLS 13 Slot 14 Control part 15 Application program 16 File system control part 17 Access control part 18 FS management information securing part 19 FS management information confirmation part 20 FS management information expansion part 21 FS management information notification part 22 FS management information reception part 25 Memory controller 27 Nonvolatile memory 100 Management information area 101 Data area 102 Master boot record / partition table 103 Partition boot sector 104, 105 FAT
106 Root directory entry 107 Directory entry 250 Host I / F unit 251 Address management unit 252 Memory access unit 253 FS notification information processing unit 254 Previous processing determination unit 271 Storage area 272 Address management information storage unit

Claims (11)

An access device connected to a nonvolatile storage device having a nonvolatile memory,
The access device is:
A file system control unit for managing file data to be read from and written to the nonvolatile storage device by a file system;
An FS management information securing unit that writes file system management information to the nonvolatile storage device before writing the file data;
An access apparatus comprising: an FS management information determination unit that rewrites the file system management information in accordance with the amount of the file data that has been written. The access device is:
An FS management information extension unit that rewrites the file system management information when the amount of file data to be written becomes larger than the file size written in the file system management information written in advance by the FS management information securing unit; The access device according to claim 1, further comprising: The access device is:
An FS management information notification unit for notifying the nonvolatile storage device of write start position information before writing the file data, and notifying the write completion information after the writing of the file data is completed;
FS management information receiving unit that issues a control signal to the nonvolatile storage device and acquires the write status information, the write end position information of the file data, and the write start position information notified before the file data is written The access device according to claim 1, further comprising: An access device connected to a nonvolatile storage device having a nonvolatile memory,
The access device is:
A file system control unit for managing file data to be read from and written to the nonvolatile storage device by a file system;
An FS management information determination unit that rewrites file system management information in accordance with the amount of the file data that has been written;
An FS management information notification unit that notifies write start position information before writing the file data to the nonvolatile storage device, and notifies write completion information after the writing of the file data is completed;
FS management information receiving unit that issues a control signal to the nonvolatile storage device and acquires the write status information, the write end position information of the file data, and the write start position information notified before the file data is written And an access device.   5. The nonvolatile memory according to claim 1, wherein the nonvolatile memory is a flash memory that can be rewritten a plurality of times or an OTP (One Time Programmable) memory that can be written only once. Access device. A memory controller that is connected to a non-volatile memory and receives external access to control the non-volatile memory,
The memory controller is
An FS notification information processing unit that receives the write start position information and the write completion information notified from the outside, and performs a process of recording in the nonvolatile memory;
In response to the control signal from the outside, the status of the writing process is determined, and according to the determination, the writing status information, the writing end position information of the file data, and the writing start position information notified before writing the file data A memory controller comprising: a previous process determination unit that notifies A non-volatile storage device having a non-volatile memory,
The nonvolatile storage device is equipped with a memory controller that controls access to the nonvolatile memory in response to external access,
The memory controller is
An FS notification information processing unit that receives the write start position information and the write completion information notified from the outside, and performs a process of recording in the nonvolatile memory;
In response to the control signal from the outside, the status of the writing process is determined, and according to the determination, the writing status information, the writing end position information of the file data, and the writing start position information notified before writing the file data A non-volatile storage device comprising: a previous process determination unit that notifies   8. The nonvolatile memory device according to claim 7, wherein the nonvolatile memory is one of a flash memory that can be rewritten a plurality of times and an OTP (One Time Programmable) memory that can be written only once. A non-volatile storage device having a non-volatile memory;
A non-volatile storage system comprising: the access device according to claim 1, wherein the access device is connected to and accessed by the non-volatile storage device. The nonvolatile memory device is
An FS notification information processing unit that performs processing of receiving the write start position information and the write completion information notified from the access device and recording them in the nonvolatile memory;
In response to the control signal from the access device, the write processing status is determined, and the write status information, the write end position information of the file data, and the write start position notified before writing the file data according to the determination The non-volatile storage system according to claim 9, further comprising: a previous process determination unit that notifies information. The nonvolatile memory is
11. The nonvolatile storage system according to claim 9, wherein the nonvolatile storage system is one of a flash memory that can be rewritten a plurality of times and an OTP (One Time Programmable) memory that can be written only once.

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