JP2007207376A - Nonvolatile storage device and memory controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonvolatile storage device which can correct error by one kind of memory controller with respect to various kinds of flash memories having different reliability. <P>SOLUTION: The memory controller 104 includes a plurality of ECC circuits 105 and 106 having different error correcting ability, and an ECC table 107 where information to show the correspondence relationship between the kind of flash memories 103 and the plurality of ECC circuits is stored. The memory controller 104 selects the ECC circuit 105 or 106 corresponded to the kind of flash memories 103 by the ECC table 107, then (a) when data are written into the flash memory 103, the memory controller 104 uses the selected ECC circuit to add an ECC code to the data of unit size, and (b) when the data are read out from the flash memory 103, uses the selected ECC circuit to correct data error of the unit size to which the ECC code is added. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a nonvolatile memory device equipped with a nonvolatile memory such as a flash memory, and a memory controller used for the nonvolatile memory device.

  In recent years, a memory card, which is a nonvolatile storage device equipped with a nonvolatile memory, has expanded its market as a storage medium for digital cameras and mobile phones. This memory card is expanding its capacity even further for applications such as higher pixel count of digital cameras and video recording on mobile phones.

  As a means for increasing the capacity of the nonvolatile memory, there is a process rule shrink. This is to increase the memory capacity by shrinking the process rule, but at that time, it is difficult to maintain the same reliability as the previous process. Another means is multilevel memory cells. By increasing the number of memory cells, the amount of information that can be stored increases. However, since it is necessary to control the state of one memory cell in more detail, it is still difficult to maintain reliability.

On the other hand, an ECC circuit that performs error correction is built in the memory controller of the nonvolatile memory device, and the reliability is reduced by strengthening the error correction function of the ECC circuit for increasing the capacity of the nonvolatile memory. (See Patent Document 1).
JP-A-6-110793

  However, in the conventional method as described above, since the error correction function of the ECC circuit needs to be changed according to the type of the nonvolatile memory mounted in the nonvolatile memory device, the number of types of the nonvolatile memory has increased. In some cases, different controllers are required depending on the degree of reliability of the nonvolatile memory to be mounted, and there is a problem that design cost and production cost increase.

In order to solve the above problem, the first nonvolatile memory device of the present invention provides:
A non-volatile storage device comprising: a non-volatile memory that stores data; and a memory controller that writes data to the non-volatile memory or reads data stored in the non-volatile memory,
The memory controller is
A plurality of ECC circuits having different error correction capabilities;
An ECC table storing information indicating a correspondence relationship between the type of the nonvolatile memory and the plurality of ECC circuits;
The memory controller selects an ECC circuit corresponding to the type of the nonvolatile memory according to the ECC table,
(A) When writing data to the nonvolatile memory, an ECC code is added to the unit size data using the selected ECC circuit;
(B) When reading data from the non-volatile memory, the selected ECC circuit is used to perform error correction of unit size data to which an ECC code is added.

The second nonvolatile memory device of the present invention is
A non-volatile storage device comprising: a non-volatile memory that stores data; and a memory controller that writes data to the non-volatile memory or reads data stored in the non-volatile memory,
The memory controller is
An ECC circuit for error correction;
An ECC table storing information indicating the correspondence between the type of the nonvolatile memory and the data size to which the ECC code is added;
The memory controller selects a data size corresponding to the type of the nonvolatile memory according to the ECC table,
(A) When writing data to the nonvolatile memory, an ECC code is added to the data of the selected size using the ECC circuit;
(B) When reading data from the non-volatile memory, the ECC circuit is used to perform error correction of data in which an ECC code is added to the data of the selected size.

The third nonvolatile memory device of the present invention is
A non-volatile storage device comprising: a non-volatile memory that stores data; and a memory controller that writes data to the non-volatile memory or reads data stored in the non-volatile memory,
The memory controller is
A plurality of ECC circuits having different error correction capabilities;
First information indicating a correspondence relationship between the type of the nonvolatile memory and the plurality of ECC circuits, and second information indicating a correspondence relationship between the type of the nonvolatile memory and a data size to which an ECC code is added are stored. An ECC table,
The memory controller selects an ECC circuit corresponding to the type of the nonvolatile memory based on the first information, and further selects a data size corresponding to the type of the nonvolatile memory based on the second information,
(A) When writing data to the nonvolatile memory, an ECC code is added to the data of the selected size using the selected ECC circuit;
(B) When reading data from the non-volatile memory, the selected ECC circuit is used to perform error correction of the selected size data to which an ECC code is added.

  In the first, second or third nonvolatile memory device of the present invention, a flash memory is preferably used as the nonvolatile memory.

  The present invention also includes a memory controller that is a component of the first, second, or third nonvolatile memory device.

  ADVANTAGE OF THE INVENTION According to this invention, the non-volatile memory | storage device which can respond to various kinds of non-volatile memories from which a reliability level differs can be provided, without increasing a design cost and a production cost.

  The nonvolatile memory device of the present invention will be described below with reference to the drawings.

(Embodiment 1)
FIG. 1 is a block diagram of a nonvolatile memory device according to Embodiment 1 of the present invention.
In FIG. 1, 101 is a memory card which is a non-volatile storage device, 102 is a host for reading / writing data from / to the memory card 101, and 103 is built in the memory card 101 and stores data transferred from the host 102. A flash memory 104 is a memory controller that is built in the memory card 101 and writes data transferred from the host 102 to the flash memory 103 and reads data stored in the flash memory 103 and transfers it to the host 102. An interface with the host 102 is performed along with the control of the memory 103.

  Reference numerals 105 and 106 denote a 3-bit ECC circuit and a 6-bit ECC circuit that perform error correction of data read from and written to the flash memory 103, and 107 denotes an ECC table.

  The ECC table 107 includes information indicating the correspondence between the type of flash memory 103 and a plurality of ECC circuits having different error correction capabilities, specifically, a plurality of different reliability that can be controlled by the memory controller 104. Information indicating which of the ECC circuits 105 and 106 is used to perform error correction is stored in the type of flash memory 103.

Hereinafter, the operation of the memory card 101 will be described.
After the power to the memory card 101 is turned on, the memory controller 104 first accesses the flash memory 103 to read information about the type of flash memory, and determines the type of flash memory.

  Next, based on the determination result, either the 3-bit ECC circuit 105 or the 6-bit ECC circuit 106 is selected as the ECC circuit corresponding to the flash memory 103 from the information stored in the ECC table 107. After the memory controller 104 selects the ECC circuit by this process once after the power is turned on, the memory controller 104 continues to use the same ECC circuit while the power is being applied.

  FIGS. 2A and 2B are diagrams showing the configuration of ECC codes corresponding to data in the flash memory 103 when the 3-bit ECC circuit 105 and the 6-bit ECC circuit 106 are used, respectively.

  The host 102 reads / writes data from / to the memory card 101 in units of 512B called sectors, but the memory controller 104 reads / writes data from / to the flash memory 103 after adding ECC codes in units of sectors.

  In FIG. 2A, a 3-bit correction ECC code is added to the sector. Such a configuration is adopted when the memory memory controller 104 determines from the information stored in the ECC table 107 that the ECC circuit suitable for the type of the flash memory 103 is 3-bit correction.

  On the other hand, in FIG. 2B, a 6-bit correction ECC code is added to a sector read / written by the host 102. Such a configuration is adopted when the memory controller 104 determines from the information stored in the ECC table 107 that the ECC circuit suitable for the type of the flash memory 103 is 6-bit correction.

  As described above, in this embodiment, the memory controller 104 includes a plurality of ECC circuits 105 and 106 having different error correction capabilities, and the 3-bit ECC circuit 105 and the 6-bit ECC circuit 106 according to the type of the flash memory 103. By using different types of memory cards, we have realized memory cards that can handle various types of flash memory with different reliability levels.

  In this embodiment, a 3-bit ECC circuit and a 6-bit ECC circuit are used as ECC circuits having different error correction capabilities. However, the present invention is not limited to this, and depending on the type of flash memory, these Needless to say, an ECC circuit having an error correction capability different from that of the ECC circuit may be used, or three or more ECC circuits having different error correction capabilities may be used in order to cope with more types of flash memories.

(Embodiment 2)
FIG. 3 is a block diagram of the nonvolatile memory device according to Embodiment 2 of the present invention.
As in the first embodiment, the memory controller of the present embodiment also includes an ECC circuit and an ECC table. However, in this embodiment, there is one ECC circuit, and information stored in the ECC table is implemented. This is different from Form 1. Hereinafter, a description will be given focusing on differences from the first embodiment.

  In FIG. 3, the memory controller 104 includes a 3-bit ECC circuit 301 and an ECC table 302. Since other configurations are the same as those of the memory card 101 of FIG. 1, portions having the same functions are denoted by the same reference numerals and description thereof is omitted.

  The 3-bit ECC circuit 301 has the same function as the 3-bit ECC circuit 105 in FIG. On the other hand, the ECC table 302 stores information indicating the correspondence between the type of the flash memory 103 and the size of the data to which the ECC code is added, that is, information about how many words of data the ECC code should be added to. ing.

  Hereinafter, the operation of the memory card 101 will be described. As in the first embodiment, the memory controller 104 accesses the flash memory 103 after the power is turned on to the memory card 101, reads information on the type of the flash memory, and determines the type of the flash memory. Next, based on this determination result, an ECC correction capability suitable for the type of the flash memory 103 is selected from the information stored in the ECC table 302.

  The ECC correction capability can be dealt with by only one type of the 3-bit ECC circuit 301 since the size of the data for performing the ECC calculation is merely changed according to the information in the ECC table 302. The memory controller 104 continues to use the same data size for a period during which power is continuously applied after selecting the size of data to be subjected to ECC calculation by this processing once after power-on.

  FIGS. 4A, 4B, and 4C are diagrams showing the configurations of ECC codes corresponding to data in the flash memory 103 when flash memories with various reliability are used.

  In the general case shown in FIG. 4A, a 3-bit correction ECC code is added to a sector (512B) which is a read / write unit of the host 102. This is because when the memory card 101 is first turned on, the memory controller 104 adds an ECC code of 3 bits per sector as the type of the flash memory 103 from the information stored in the ECC table 302. This is because it was judged appropriate.

  In the flash memory 103 that needs to be added with a higher-performance ECC code having lower reliability than that assumed in FIG. 4A, as shown in FIG. 4B, 256B, which is half of the sector. A 3-bit correction ECC code is added. This is because the memory controller 104 determines from the information stored in the ECC table 106 that the type of the flash memory 103 is appropriate to add an ECC code of 3 bits per half sector. The ECC code of 3 bits per half of the sector can be applied to the flash memory to which the ECC code of 6 bits per sector should be added because it is equivalent in error correction.

  As shown in FIG. 4C, in the flash memory 103 that only needs to add a ECC code having higher reliability and lower function than the case assumed in FIG. 4A, A 3-bit correction ECC code is added to 1024B. This is because the memory controller 104 determines from the information stored in the ECC table 106 that the type of the flash memory 103 is appropriate to add an ECC code of 3 bits per 2 sectors. The ECC code of 3 bits per 2 sectors can be applied to the flash memory to which 1-bit ECC per sector is to be added because it is equivalent in error correction.

  As described above, in the present embodiment, by changing the number of words of data to which an ECC code is added in accordance with the type of flash memory, only one type of ECC circuit is provided, and various reliability levels are different. A memory card compatible with flash memory has been realized.

(Embodiment 3)
In the first embodiment described above, a plurality of ECC circuits having different error correction capabilities are used properly, and in the second embodiment, the number of words of data to which an ECC code is added is changed to correspond to flash memories having different reliability levels. However, in the present embodiment, a combination of the configuration of the first embodiment and the configuration of the second embodiment is compatible with flash memories having a wider range of reliability levels.

  Specifically, using the memory controller 104 of FIG. 1, the ECC table 107 includes first information indicating the correspondence between the type of the flash memory 103 and a plurality of ECC circuits having different error correction capabilities, and a 3-bit ECC circuit. For each of the 105 and 6-bit ECC circuit 106, second information indicating the correspondence between the type of the flash memory 103 and the size of the data to which the ECC code is added is stored, and the first information is stored according to the type of the flash memory to be mounted. By using a combination of the second information and the second information, a memory card capable of supporting various types of flash memories having different reliability levels is realized.

  Therefore, if the memory controller of this embodiment is used, the error correction of the form shown in FIGS. 2 (A), (B) and FIGS. 4 (A), (B), (C) will be exceeded. For example, error correction in the form of adding a 6-bit ECC code to half of the sector (256B) is also possible.

  The nonvolatile memory device and the memory memory controller according to the present invention are compatible with various types of nonvolatile memories with different reliability levels, and will increase in the future as the capacity increases. Since it can cope with multi-values, it leads to expansion of applicable fields of memory cards.

1 is a block diagram showing a configuration of a nonvolatile memory device according to Embodiment 1 of the present invention. The figure which shows the relationship between sector data and ECC in Embodiment 1. The block diagram which shows the structure of the non-volatile storage device in Embodiment 2 of this invention The figure which shows the relationship between sector data and ECC in Embodiment 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Memory card 102 Host 103 Flash memory 104 Memory controller 105 3-bit ECC circuit 106 6-bit ECC circuit 107 ECC table 301 3-bit ECC circuit 302 ECC table

Claims (9)

A non-volatile storage device comprising: a non-volatile memory that stores data; and a memory controller that writes data to the non-volatile memory or reads data stored in the non-volatile memory,
The memory controller is
A plurality of ECC circuits having different error correction capabilities;
An ECC table storing information indicating a correspondence relationship between the type of the nonvolatile memory and the plurality of ECC circuits;
The memory controller selects an ECC circuit corresponding to the type of the nonvolatile memory according to the ECC table,
(A) When writing data to the nonvolatile memory, an ECC code is added to the unit size data using the selected ECC circuit;
(B) When reading data from the non-volatile memory, the non-volatile memory device performs error correction of unit-size data to which an ECC code is added using the selected ECC circuit.   The nonvolatile memory device according to claim 1, wherein a flash memory is used as the nonvolatile memory. A non-volatile storage device comprising: a non-volatile memory that stores data; and a memory controller that writes data to the non-volatile memory or reads data stored in the non-volatile memory,
The memory controller is
An ECC circuit for error correction;
An ECC table storing information indicating the correspondence between the type of the nonvolatile memory and the data size to which the ECC code is added;
The memory controller selects a data size corresponding to the type of the nonvolatile memory according to the ECC table,
(A) When writing data to the nonvolatile memory, an ECC code is added to the data of the selected size using the ECC circuit;
(B) When reading data from the nonvolatile memory, the ECC circuit is used to perform error correction of data in which an ECC code is added to the data of the selected size. .   The nonvolatile memory device according to claim 3, wherein a flash memory is used as the nonvolatile memory. A non-volatile storage device comprising: a non-volatile memory that stores data; and a memory controller that writes data to the non-volatile memory or reads data stored in the non-volatile memory,
The memory controller is
A plurality of ECC circuits having different error correction capabilities;
First information indicating a correspondence relationship between the type of the nonvolatile memory and the plurality of ECC circuits, and second information indicating a correspondence relationship between the type of the nonvolatile memory and a data size to which an ECC code is added are stored. An ECC table,
The memory controller selects an ECC circuit corresponding to the type of the nonvolatile memory based on the first information, and further selects a data size corresponding to the type of the nonvolatile memory based on the second information,
(A) When writing data to the nonvolatile memory, an ECC code is added to the data of the selected size using the selected ECC circuit;
(B) When reading data from the nonvolatile memory, the nonvolatile memory device performs error correction of the selected size data to which an ECC code is added, using the selected ECC circuit. .   6. The nonvolatile memory device according to claim 5, wherein a flash memory is used as the nonvolatile memory. A memory controller that writes data to a nonvolatile memory or reads data stored in the nonvolatile memory,
A plurality of ECC circuits having different error correction capabilities;
An ECC table storing information indicating a correspondence relationship between the type of the nonvolatile memory and the plurality of ECC circuits;
Select an ECC circuit corresponding to the type of the nonvolatile memory by the ECC table,
(A) When writing data to the nonvolatile memory, an ECC code is added to the unit size data using the selected ECC circuit;
(B) When reading data from the non-volatile memory, the memory controller is configured to perform error correction of unit size data to which an ECC code is added, using the selected ECC circuit. A memory controller that writes data to a nonvolatile memory or reads data stored in the nonvolatile memory,
An ECC circuit for error correction;
An ECC table storing information indicating a correspondence relationship between the type of the nonvolatile memory and the size of data to which the ECC code of the ECC circuit is added;
Select a data size corresponding to the type of the nonvolatile memory by the ECC table,
(A) When writing data to the nonvolatile memory, an ECC code is added to the data of the selected size using the ECC circuit;
(B) When reading data from the non-volatile memory, the ECC controller is used to perform error correction of data in which an ECC code is added to the data of the selected size. A memory controller that writes data to a nonvolatile memory or reads data stored in the nonvolatile memory,
A plurality of ECC circuits having different error correction capabilities;
First information indicating a correspondence relationship between the type of the nonvolatile memory and the plurality of ECC circuits, and second information indicating a correspondence relationship between the type of the nonvolatile memory and a data size to which an ECC code is added are stored. An ECC table,
An ECC circuit corresponding to the type of the nonvolatile memory is selected according to the first information, and a data size corresponding to the type of the nonvolatile memory is selected according to the second information.
(A) When writing data to the nonvolatile memory, an ECC code is added to the data of the selected size using the selected ECC circuit;
(B) When reading data from the non-volatile memory, the memory controller is configured to perform error correction of the selected size data to which an ECC code is added, using the selected ECC circuit.

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