JPH04307647A - Memory card storage control system - Google Patents

Abstract

PURPOSE:To control a data area including a defective part of the information recorded into a memory card having an EEPROM. CONSTITUTION:An error bit map is formed in a control area to show the propriety of the storage state of each cluster of a date area in a single bit. The error bit map is held at '1' equal to an initial state as long as the cluster storage state is normal in a cluster verifying state. Meanwhile '0', i.e., the inverted value of the initial state is written in the error bit map if the cluster storage state is abnormal in the cluster verifying state. When '0' is written, no erasure processing is required for an EEPROM. Then the control area can be rewritten just by writing '0' over the state of '1'. In an erasure state, the error bit map is once reed out of a system memory and then returned to a prescribed position of the control, area after erasion. As a result, a defective cluster is never used after erasure and the data can surely be stored.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a storage management system for a memory card that stores data such as image data and character data.

0002

[Prior Art] In recent years, semiconductor memories have been used in place of floppy disks as media for recording image data in electronic still cameras and character data in word processors.
Smaller memory cards have come into use.

Conventionally, such memory cards have used static RAM (hereinafter referred to as SRAM) which can perform high-speed reading and writing. However, since this SRAM is a volatile semiconductor memory, it requires a backup battery inside the memory card, and when storing large amounts of data such as image data, it becomes expensive and the memory The problem was that the card prices were high.

Therefore, in recent years, EEP, which is a non-volatile semiconductor memory that is inexpensive and does not require a backup battery, has been developed.
The use of ROM (electrically erasable/rewritable read-only memory) in memory cards is being considered. This EEPROM has an excellent storage life of more than 10 years without batteries, and in recent years has come to have read and write speeds comparable to SRAM, and is about one-fourth the price of SRAM. being developed.

By the way, various storage management systems for memory cards have been proposed in order to efficiently read and write data stored in storage media such as memory cards as described above. For example, patent application Hei 1-31
Memory card storage management method of No. 7796 and patent application No. 1
There was a storage management method applied to an image recording and reproducing device in No. 326118. In these storage management systems, data management information is stored in a recording medium along with data recording. When reading data, the management information is referenced to read the data, and when data is to be written, the management information is referenced to search for free space and written, and after the data is written, the management information is was rewritten and stored on the recording medium.

[0006]

[Problem to be solved by the invention] However, EEP
In a memory card using a ROM, the EEPROM has a write limit, so if the EEPROM exceeds the write limit, errors may occur in the written data. Therefore, it was necessary to obtain the management information.

[0007] The above-mentioned conventional technology does not take this into account, and if an error occurs in any data area during writing or reading, the memory card is considered to be defective and other data areas are not usable. However, there was a problem in that the card itself became unusable. in this case,
Cards that store image data have a large capacity, so if there is a large usable data area, there will be a lot of waste.Therefore, it has been desired to develop an effective management system for memory cards using EEPROM.

[0008] Furthermore, in the management method of a memory card equipped with such an EEPROM, since the EEPROM needs to be erased when data is rewritten, this erasure processing must be taken into consideration. Flash type EEPROM
In this case, writing can be performed one byte at a time, similar to SRAM, but erasing can only be performed in a predetermined block or all, and the method of rewriting management information every time has the risk of erasing other information. The problem arises that they cannot be hired. Furthermore, if management information is created on the system side each time, there are various problems in that the system configuration becomes complicated and the processing becomes complicated.

The present invention eliminates the drawbacks of the prior art, and makes it possible to use a memory card equipped with an EEPROM, even if part of the data area becomes defective, other good data areas can be used. It is an object of the present invention to provide a storage management system for a memory card that can manage the data area without imposing a burden on the system side.

0010

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention includes an electrically erasable and rewritable EEPROM as a storage element, and stores data and management information in this EEPROM. In the storage management system of a memory card, the data area is divided into multiple areas into which data is written, and the management information for these multiple data areas is written in an initial state in which the contents of the EEPROM are all the same value. One bit is allocated to each data area in the management area, and an error bit map is formed in which each bit indicates whether the storage status of the data area is good or bad. , this error bitmap retains the same value as the initial state if the storage state of the data area is good, and if an error occurs in the data area, the value that is the inverted value of the initial state is retained. It is characterized by indicating a defect in the data area that has been written.

In this case, the error bitmap once written is read out when erasing the contents of the EEPROM, and after the EEPROM is erased,
It is written again to a predetermined location in the management area.

Furthermore, in this management method, when data is written, a verification is performed to read and verify the written data, and if an error is found in the data during the verification, the bit code of the error bitmap corresponding to the data area is changed. It is recommended that the data to be written to that data area be rewritten to the next good data area.

In this case, when reading data from a data area, the error bitmap corresponding to the data area is referred to, and if the bit sign of this error bitmap is reversed from the initial state value, Access the next good data area after that data area without accessing the data area corresponding to that bit.

On the other hand, in a memory card system that stores data and management information in a memory card equipped with an EEPROM as a storage element, this system stores data in an initial state in which all the contents of the EEPROM have the same value. a formatting means for forming a plurality of data areas in which the data are written, and a management area in which management information of these data areas is written, which includes an error bitmap indicating whether the storage condition of the data area is good or bad; An error bitmap rewriting means for rewriting an error bitmap value corresponding to the data area to an inverted value without performing an erase operation from an initial state value when an error occurs during verification;
A storage means for reading and storing an error bitmap when erasing the contents of the ROM, and an error bitmap write for writing the error bitmap read into the storage means into a predetermined position in a management area when formatting the EEPROM after erasing it. It is characterized by comprising a means for loading.

[0015]

[Operation] According to the memory card storage management system of the present invention, the error bitmap provided in the management area indicates whether the storage status of each data area is good or bad.
Display in bits. In this case, each bit of the error bitmap is held at the same value as the initial state if the storage state of the corresponding data area is normal, and becomes a value different from the initial state if an abnormality occurs in the storage state. Will be rewritten. Since this rewriting is the same operation as writing data to the initial state, that is, writing after erasing, there is no need to perform an erasing process, and it is possible to rewrite management information without an erasing operation in the EEPROM. Also,
When erasing the contents of the EEPROM, the error bitmap is once read out to the system side, and after the erasure is performed, it is written back to a predetermined position in the management area. This makes it possible to effectively utilize each data area even after erasing the EEPROM.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a memory card storage management system according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic diagram showing an embodiment of a memory card employing the memory card storage management system according to the present invention. In this figure, a memory card 10 includes a flash erasable EEPROM (electrically erasable and rewritable read-only memory) cell 16 as a semiconductor memory for storing data. This memory card 1
0 is attached to a digital still camera (hereinafter referred to as DS camera), etc., and converts the digital image data into EEP.
This is an image recording medium that is stored in the ROM 16. The memory card 10 in this embodiment includes a control section including a data processor 12, a memory interface 14, a controller 18, and a map memory 20.

The data processing processor 12 converts the image data captured by the DS camera into a predetermined data format that can be recorded in the EEPROM 16, and
This is a data conversion circuit that reversely converts the image data read from the PROM 16 into a predetermined data format that can be reproduced by a reproduction device or the like.

The memory interface 14 converts the image data converted by the data processing processor 12 into an EEPRO.
This is a memory I/O interface circuit that transfers recorded data to the M cell 16 and also transfers recorded data read from the EEPROM cell 16 to the data processing processor 12. Further, this memory interface 12 is an interface that transfers a control signal sent from the controller 18 to the EEPROM cell 16.

The controller 18 controls each block 12,1
This is a control circuit for recording image data in the EEPROM cell 16 or reading image data recorded in the EEPROM cell 16 by controlling the EEPROM cell 16. For more information,
This controller 18 is connected to the EEPROM from the DS camera.
When image data to be recorded on the data processing processor 16 is sent, a timing signal is sent to the data processing processor 12 to control the data conversion. When writing the image data converted by the data processing processor 12 to the EEPROM 16, a control signal for writing and a write destination address are generated based on the control signal supplied from the DS camera, and these are sent to the memory interface 14. The data is sent to the EEPROM 16 via the EEPROM 16. In this case, when image data is written to the EEPROM 16, the controller 18 has a function of once reading the written image data via the memory interface 14 and verifying it, that is, checking whether the data has been written correctly. . When reading image data stored in the EEPROM 16, a control signal for reading and a read destination address are generated based on the control signal supplied from the DS camera, and these are sent to the EEPROM 16 via the memory interface 14. do. At this time, a timing signal is sent to the data processing processor 12 to control the image data read out via the interface 14 to be inversely converted and output to the playback device.

[0021] Furthermore, the controller 1 in this embodiment
8 is for sending out an erase signal and formatting the EEPROM 16 in its initial state, and the EEPROM 16 to be described later.
It performs control related to content management of the EEPROM 16, such as searching the directory area 30 of the M16 and writing its serial number 40, changing the error bit map 36, and saving the error map bit 36 when erasing. Specifically, this controller 18 has a function of sending an erase signal to the EEPROM 16 via the memory interface 14 when a memory erase instruction is given from the camera side when the memory card 10 is attached to the camera. In this case, as shown in Figure 2(a), all the contents of the EEPROM 16 are erased and the EEPROM
All contents of PROM16 are shown in hexadecimal ”FF”
FF" state, that is, an all "1" state. The controller 18 stores the EEPROM 16 in this state into a header area 30 and a directory area 32, which are storage management areas 24, and data divided into clusters, as shown in FIG. In this case, an error bit map 36, which is one of the features of this embodiment, is formed in the header area 30 as shown in FIG. 5(a). Map 36 is
Data area 2, one bit at a time, starting from the smallest address
6 clusters.

Furthermore, when writing image data, this controller 18 searches the header area 30 and the directory area 22 to find an unrecorded directory area 20.
It has a function to sequentially write the serial number 40 in the first area of . By writing this serial number, it is possible to distinguish between used and unused clusters in the data area 24. Furthermore, when image data is written and verified, if the data recording is abnormal, that is, if the written data has a high error rate, the controller 18 considers that cluster to be defective and sets the error bit to Control is performed to rewrite the map 36 and change the writing destination of image data. Rewriting the error bitmap 36 is different from processing that involves rewriting or erasing data in the EEPROM, and is performed by simply overwriting the initial state, that is, rewriting the bits with a value of "1" to "0". Once the error bitmap 36 has been written, the EEPRO
When erasing the contents of M16, error bitmap 3
6 is read into the memory 20, the data is erased, and after the data is erased, a process of writing from the memory 20 to the header area 20 is performed.

To explain the details of the EEPROM 16 formatted by this controller 18, the data area 26 has a plurality of image storage areas 26 as shown in FIG.
a, 26b, . ．． ．． are divided into image storage areas 26a, 26b. ．． ．． is constituted by the smallest recording management unit of the EEPROM 16. For example, the respective image storage areas 26a, 26b, . ．． ．． is composed of cluster units into which image data for one image can be written, and usually data for one image is stored in one cluster. If the image data has a capacity that cannot be written in one cluster, it is stored across multiple clusters.

The header area 30 is a management area in which, for example, the title of the card, the memory size, an error map indicating defective locations in the memory in the data area 26, a parity check, etc. are written, and is mainly a fixed management area that does not need to be rewritten. This is the area where information is written. As shown in FIGS. 5(a) and 5(b), in the error map, one bit is assigned to each cluster in the data area 26, and each bit indicates the quality of the storage state of each cluster. .

The directory area 32 is the data area 26
It consists of multiple data management areas provided corresponding to each cluster, and normally one management area is allocated to one cluster, but if one cluster cannot store the image data of one image, it is divided into several clusters. One management area is allocated. The format is shown in FIG.

In the figure, a leading area 40 is an identification area in which an image identification code or a serial number such as a serial number or directory number is written. This identification area 40 is assigned a number of bytes that can represent the number of clusters in the data area 26. for example,
Consecutive 2-byte numbers such as serial numbers "0001" to "FFFE" are sequentially written. In this identification area, a usage code such as a serial number is written when data is written in the corresponding data area 26, and when it is not used, it is held in the initial state "FFFF". As a result, clusters 26a, 26b, . ．．
．． This indicates the usage status of the .

The file name area 41 is the data area 26
This is an area where the cluster in which image data of is stored, that is, the name given to the file by the user, is stored. In this file name area 41, the user can write a file name using arbitrary characters or numbers.
A capacity of 6 bytes is allocated.

The storage date and time of image data or the photographing date and time are written in the date and time area 42. In the case of storage date and time, by storing image data every time a photograph is taken, it becomes almost the same as the photographing date and time. This date and time data is sent from the camera via the data processor 12 when storing image data. The reserve area 43 is an area that can be used arbitrarily, and is allocated, for example, 2 bytes.

In the start cluster area 44, the start address of the start cluster in the data area 24 for storing image data is written. End cluster area 45
is the start address or end address of the final cluster when image data is stored in multiple clusters. If the image data fits into one cluster, the same address as the start cluster area 44 or its final address is written. These address data are calculated by the controller 18 based on the data capacity sent from the camera side at the time of data storage, and are sent via the memory interface 14, respectively.

Two bytes are each allocated to areas 43 and 44. The amount of stored data is written in the data number storage area 46. If the data spans multiple clusters, only the data capacity of the last cluster is written. This data capacity is supplied from the camera side at the time of data storage. Two bytes are also allocated to this area 46.

The map memory 20 is composed of a small-capacity SRAM or the like, and an error bitmap 36 is written therein when the EEPROM 16 is erased. Specifically, if the capacity of the data area 26 is 2M bits and one cluster is 8K bytes, the data area 26 has 32 clusters and the size of the error bit map is 4 bytes, so the map memory 20 may be one that can store a capacity of 4 bytes. This memory 20 does not require a backup battery, and is supplied with power supply voltage from the DS camera side when the card is inserted, and the memory of the error data map is erased when the card is removed from the camera.

With the above configuration, the operation of the memory card 10 in this embodiment will be explained with reference to FIGS. 6 to 8. FIG. 6 is a write mode flowchart showing data write processing. In this figure, when the memory card 10 is attached to the DS camera and the operator presses the erase mode button, in step 100 chip erase is performed, that is, all existing records in the EEPROM 16 are erased. For this operation, an erase signal is supplied from the camera to the controller 18, and the controller 18 that receives the erase signal erases the data from the EEPROM 16 via the memory interface 14.
Sends an erase signal to. As a result, the storage area is reduced to Figure 2 (
As shown by diagonal lines in a), all bytes are in the state of "FF", that is, all "1".

Next, in step 102, formatting is performed. In other words, as shown in FIG. 2(b), the header area 30 and the directory area 3
2. The data area 26 is divided under the control of the controller 18. At this time, fixed information is written in the header area 30. The error bitmap 36 is maintained in a state of all "1"s, as shown in FIG. 4(a). This step 10
2 is not performed if step 100 is not performed, that is, if the operator does not press the erase mode button. In this case, if the erase mode button is not pressed for a predetermined period of time after the memory card 10 is inserted into the camera, the fixed information in the header area 30 is automatically read out, and then the next step 104 is started. be done.

In this step 104, a first cluster is selected. This is because the controller 18 sequentially searches the head area of the directory area 32, that is, the identification area, selects a management area that has the same state as the first searched "FFFF" value, that is, the initial state, and corresponds to that management area. Select a cluster in the data area 26. This makes it possible to take pictures.

[0035] When photography is performed, the operator inputs the identification name of the photographed image, etc. into the camera. The camera sends the input name, date and time, and capacity of captured image data to the memory card 10. As a result, in step 106, management data regarding these data is written into the directory area 32 searched in step 104. In this case, the file name 41, date and time 32, and number of data 46 are written, excluding the usage code, start cluster 44, and end cluster 45.

Next, image data representing the photographed image is sent from the camera side to the memory card 10. As a result, in step 108, the image data is
Written to OM16. In this case, when the input image data is converted by the data processing processor 12, the controller 18 sends the start address of the cluster selected in step 104 via the memory interface, and also sends a write control signal to write the first Byte data is written to a cluster, and the address is sequentially incremented to write data to the cluster in units of bytes.

When the data writing is completed, the process proceeds to step 110, and the controller 18 verifies the data. If the written data is normal in this verification, a serial number, for example, is written in the identification area of the directory 32, and the start cluster 44 is
, and end cluster 45, step 1
Proceed to 12. If an error is detected, the controller 18
repeats verification several times. If there is an error in the data all times, it is determined that the cluster is abnormal, and in step 114, the cluster abnormality is detected in the error data map 36.
In order to register it, rewrite that bit to “0”. Next, the management data written above is transferred to the next management area, and the image data is rewritten to the next cluster. The rewritten cluster is also verified, and if it is normal, the usage code and cluster addresses 44 and 45 are written in the management area, and the process proceeds to step 112. In step 112, the end of data writing is checked. If it is finished, the step is finished; if not, the process returns to step 110.

Next, the search/reproduction mode will be explained with reference to FIG. In this figure, the memory card 10 searches the directory area 32 of the EEPROM 16 for the serial number upon receiving the designation of a desired image from the playback device at step 130 . If the specified number is found in step 132, the process proceeds to step 136, where all data of the image corresponding to the serial number is read out, or if the specified number is not found, the step is terminated.

FIG. 8 shows an erase mode in which the EEPROM 16 is erased after an abnormality occurs in the cluster in the write mode. In this mode, in step 150, when the memory card 10 is installed in the DS camera, a process is performed to send a command to chip erase (completely erase) the existing format records of the EEPROM 16 to the memory card 10. Then,
In step 152, the controller 18 controls the EE
A process is performed to transfer the error bitmap 36 of the header area 30 stored in the PROM 16 to the memory 30 via the card interface 14. Then step 15
At step 4, the controller 18 sends an erase signal to erase all records in the EEPROM 16. Next, in step 156, the controller 18 performs formatting to divide the completely erased EEPROM 16 into the header area 30, directory area 32, and data area 26 shown in FIG. At this time, the error bit map 36 is transferred from the memory 20 to a predetermined position in the header area 30 of the EEPROM 16 via the card interface 14. This completes the erase mode.

According to this embodiment, the directory area 3 is arranged so as to correspond to each cluster of the data area 26.
2, and a usage code such as a serial number is given to the beginning of each management area when writing data, so there is no need to rewrite the management information every time data is written. Furthermore, by using consecutive numbers as the codes used, data can be read out smoothly.

Furthermore, since an error bitmap is created in the header area 30 corresponding to each cluster, if there is an error in a cluster, a value "0" different from the initial state is written to the bit corresponding to that cluster. , the cluster will no longer be accessed. Therefore, EEPRO
Even if an error occurs in part of M16, data can be written and read using other valid clusters. When rewriting the error bitmap, instead of rewriting with normal EEPROM erasing, the initial state value is set to a different "0".
It is safe because there is no risk of erasing other information. Also, error bitmap 36
is temporarily saved in the map memory 20 when the EEPROM 16 is erased, so that the data area after erasing can be used effectively without any problem.

In the above embodiment, a control unit including a data processing processor 12 and a controller 18 is provided in the memory card 10, but these can be separated from the card as an adapter, or can be connected to an external device such as a DS camera. It may also be provided. Further, in the above embodiment, the format of the directory area 32 is configured as shown in FIG. 4, but the present invention is not limited to this, and any other arbitrary configuration may be used.

[0043]

As explained above, according to the memory card storage management system of the present invention, the error bitmap provided in the management area indicates the quality of the storage status of each data area using one bit. do. in this case,
Each bit of the error bitmap is held at the same value as the initial state if the storage state of the corresponding data area is normal, and is rewritten to a value different from the initial state when an abnormality occurs in the storage state. This rewriting is the same operation as writing data to the initial state, that is, writing after erasing, so there is no need to perform an erasing process, and the EE
It is possible to rewrite management information without erasing the PROM. Further, when erasing the contents of the EEPROM, the error bitmap is once read out to the system side, and after the erasure is performed, it is written back to a predetermined position in the management area. This makes it possible to effectively utilize each data area even after erasing the EEPROM.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram of a memory card system showing an embodiment of a memory card storage management method according to the present invention.

FIG. 2 is a configuration diagram showing formatting of an EEPROM in this embodiment.

[Figure 3] Formatted E in this example
FIG. 2 is an explanatory diagram for showing the contents of the EPROM 16. FIG.

FIG. 4 is a configuration diagram showing the contents of a directory area 32 in this embodiment.

FIG. 5 is a configuration diagram showing the contents of an error bitmap 36 in this embodiment.

FIG. 6 is a flowchart for explaining a data write operation in this embodiment.

FIG. 7 is a flowchart for explaining data search and reproduction operations in this embodiment.

FIG. 8 is a flowchart for explaining an erase operation in this embodiment.

[Explanation of symbols]

10 Memory card 12 Data processing processor 14 Memory interface 16 EEPROM cell 30 Map memory 24 Memory management area 36 Error bit map

Claims (5)

[Claims] 1. A storage management system for a memory card that is equipped with an electrically erasable and re-writable EEPROM as a storage element, and stores management information together with data in the EEPROM, wherein all contents of the EEPROM have the same value. In the initial state, the EEPROM has
A data area divided into multiple sections into which data is written;
A management area is formed in which management information of the plurality of data areas is written, and the management area has one bit corresponding to each data area indicating whether the storage state of each of the data areas is good or bad. An error bitmap indicated by the assigned bit codes is formed, and each bit code of the error bitmap is kept as the same value as the initial state if the storage state of the data area is good. A storage management system for a memory card, characterized in that when an error occurs in the data area, a value inverted from the initial state value is written to indicate that the data area is defective. 2. The memory card storage management method according to claim 1, wherein the error bitmap is an EEP
A storage management system for a memory card, characterized in that when erasing the contents of a ROM, the contents are read out once and then written back to a predetermined position in the management area after the EEPROM is erased. 3. In the memory card storage management method according to claim 1 or 2, in the management method, when data is written, verification is performed to read and verify the written data, and at the time of the verification, the data is If there is an abnormality, rewriting the bit code of the error bitmap corresponding to the data area,
A memory card storage management system characterized in that data to be written in that data area is rewritten in the next good data area. 4. The storage management method for a memory card according to claim 3, wherein when reading data from the data area, the management method refers to the error bitmap corresponding to the data area and reads the data from the data area. If the bit sign of the error bitmap is reversed from the initial state value, the data area corresponding to that bit is not accessed and
A storage management method for a memory card, characterized in that a good data area next to the data area is accessed. 5. A memory card system for storing data and management information in a memory card having an EEPROM as a storage element, wherein the system is configured to store data and management information thereof in an initial state in which the contents of the EEPROM are all the same value. , formatting means for forming a plurality of data areas into which the data is written, and a management area into which management information of the data areas is written, which includes an error bitmap indicating whether the storage state of the data area is good or bad. and an error bitmap rewriting means for rewriting the value of the error bitmap corresponding to the data area to an inverted value without performing an erase operation from the initial state value when an error occurs during data verification;
storage means for reading and storing the error bitmap when erasing the contents of the EEPROM;
A memory card system comprising error bitmap writing means for writing an error bitmap read into the storage means at a predetermined position in a management area during formatting after erasing M.