JP2001154926A - Storage method using flash memory and recording medium recording storage control program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent data from being lost even when power interruption or the like occurs while writing or erasing the data to/from a flash memory. SOLUTION: The flash memory 15 for which an area for storing the data is constituted on the two surfaces of a first nonvolatile surface 15A and a second nonvolatile surface 15B and a RAM 16 for backup provided with a backup surface 16A and backed up by a secondary battery are provided. The data are stored in the areas on the total of three surfaces for which the areas on the two surfaces of the first nonvolatile surface 15A and the second nonvolatile surface 15B and the area on the one surface of the backup surface 16A are gathered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a storage method using a flash memory and a recording medium on which a storage control program is recorded. More specifically, the present invention relates to a method for storing data even when data is changed during operation. The present invention relates to a storage method in a case where a flash memory is used as a non-volatile memory for storing data in a storage device in which data is stored, and a storage medium storing a storage control program.

[0002]

2. Description of the Related Art Conventionally, storage of data that needs to be changed includes:
EEPROM, which is a non-volatile memory, is generally used. However, in recent years, the inside of the flash memory has been divided into two blocks, and a flash memory capable of reading from one block while writing or erasing one block has become widespread. This allows
It has been required to store the operation data in a flash memory for storing programs so as to eliminate the EEPROM, thereby reducing cost and mounting area. However, the flash memory has a limit on the number of times of writing. If the limit is exceeded, a writing error or erasing error occurs, and writing or erasing takes time. And the data may be destroyed. Also, as is well known, in writing to a flash memory, "1" can be changed to "0", but "0" cannot be changed to "1". It is necessary to write all new data after erasing all the areas in which is written and setting all bits to "1".

In order to cope with write and erase errors due to the limitation of the number of times of writing, for example, Japanese Patent Laid-Open No. 6-33280
As disclosed in No. 6, it has been proposed to stop using a region where a write error has been detected and write data to a substitute region. That is, in the above publication, in a storage system having a semiconductor memory unit having a storage unit using a flash memory as a storage medium, and a host system that transmits and receives information to and from the semiconductor memory unit, the semiconductor memory unit, An interface circuit for transmitting and receiving information to and from the host system, a control circuit for controlling reading and writing of information from and to the storage unit, and detecting an error area of the storage unit; and an unused circuit for each area of the storage unit. When the control circuit detects an error in the state of use, an unused area is allocated as an alternative area instead of the error area of the storage section, and a correspondence between the allocated alternative area and the error area is determined. The control circuit refers to the memory management unit and controls reading and writing of information from and to the storage unit. Techniques to perform is disclosed.

[0004]

However, the technique disclosed in Japanese Patent Application Laid-Open No. Hei 6-332806 is based on the premise that power is supplied to the device stably. For example, the power is turned off while data is being written. If the operation data is lost, the operation data may be completely lost because the erasure is performed before the writing. However, especially in the case of a portable terminal or the like, the power supply may be suddenly cut off due to unexpected handling of the terminal user, and the storage method must also consider sudden power-off. The above technology does not consider the control in the case of sudden power off etc.
Operation data may be lost when the power is turned off. Therefore, the problem that it is difficult to use a flash memory for a portable terminal and other devices that need to store data that should not be lost remains unsolved. The present invention has been made in view of the above-described circumstances, and a storage method using a highly reliable flash memory without losing data even when a power failure or the like occurs during writing or erasing data in the flash memory. It is an object of the present invention to provide a recording medium on which a storage control program is recorded.

[0005]

According to a first aspect of the present invention, there is provided a storage method using a flash memory, wherein an area for storing data includes a first nonvolatile surface and a second nonvolatile surface. A flash memory having two surfaces; a backup RAM having a backup surface and backed up by a secondary battery;
Data is stored in a total of three areas including a nonvolatile surface, a second nonvolatile surface, and a backup surface.

According to a second aspect of the present invention, there is provided a storage method using the flash memory according to the first aspect, wherein the data stored in the flash memory and the backup RAM is checked by adding the data in units of one byte. It is characterized by comprising a sum and determination data for determining whether the data is destroyed.

According to a third aspect of the present invention, there is provided a storage method using the flash memory according to the first or second aspect.
When rewriting data, data is rewritten in the order of the backup surface, the first non-volatile surface, and the second non-volatile surface, and old data before rewriting or after rewriting is completed until rewriting of the second non-volatile surface is completed. Characterized in that the new data exists in the flash memory.

[0008] Further, the invention according to claim 4 is based on claim 1,
4. The storage method using a flash memory according to item 2 or 3, wherein the first nonvolatile surface and the second nonvolatile surface each include an area for storing a block management table, and the block management table includes the first nonvolatile surface or Any one or a plurality of states during writing / writing completed / writing not performed / erasing / erasing completed / erasing not performed on the second nonvolatile surface is written.

[0009] The invention according to claim 5 is the invention according to claims 1 to 4.
The validity of each of the first non-volatile surface, the second non-volatile surface, and the backup surface is confirmed, and the copy source is determined from among the surfaces determined to be valid. Is determined in accordance with the priority order of backup side> first non-volatile side> second non-volatile side, and a copy-permitted side is determined under the condition that the highest-priority valid side does not match the checksum, It is characterized in that the operation data is copied only when there is an unprocessed copy-permitted surface.

[0010] The invention according to claim 6 is the invention according to claims 1 to 5.
A storage method using the flash memory according to any one of the above, wherein the flash memory and the backup R
The AM is connected to a CPU of a control unit of the mobile terminal via an address data bus, and the data is operation data of the mobile terminal.

According to a seventh aspect of the present invention, there is provided a recording medium recording a storage control program for causing a computer to function as a storage method using the flash memory according to any one of the first to sixth aspects. I have.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. The description will be specifically made using an embodiment. FIG. 1 is a block diagram showing an electric configuration of a portable terminal to which a storage method using a flash memory according to an embodiment of the present invention is applied, and FIG. 2 is a flash memory and a backup RAM used in the storage method.
And FIG. 3 is a diagram showing a block management table set in the flash memory. As shown in FIG. 1, the mobile terminal of this example is roughly constituted by a radio unit 2 for wirelessly communicating with a base station via an antenna 1 and a control unit 3 for handling a baseband signal. The wireless unit 2 includes a receiving unit 4 and a transmitting unit 5. The receiving unit 4 includes a high-frequency amplifier, a receiving mixer, an intermediate frequency amplifier, a demodulator, and the like, although not shown. The transmitting unit 5 includes a transmission power amplifier, a transmission mixer, a modulator, and the like. The control unit 3 includes a baseband processing circuit 6 for performing modulation / demodulation processing, a CPU 7 for controlling the entire apparatus, and a user interface processing circuit 8 for controlling user-related processing. The user interface processing circuit 8 mainly performs input detection of the key 10, controls charging from the charging unit 11, and controls the power supply 12.

The CPU 7 has a flash memory 15 as a nonvolatile memory via an address data bus 14,
Static RAM (SR
AM) and the display unit 1
7 are connected. The CPU 7 performs various controls described below by inputting the recording medium 20 on which the baseband processing control program 70, the user interface control program 71, the flash memory control program 72, the backup RAM control program 73, and the display control program 74 are recorded. It has become. The flash memory 15 stores a program and data that needs to be rewritten but must be held semi-permanently (hereinafter, this data is referred to as operation data). The backup RAM 16 is backed up by a secondary battery 18. As shown in FIG.
5 and the backup RAM 16 are provided with areas for storing operation data. That is, the flash memory 1
5 are provided with a first nonvolatile surface 15A and a second nonvolatile surface 15B, and the first nonvolatile surface 15A and the second nonvolatile surface 15B each include an area for storing a block management table as described later. Provided. The backup RAM 16 has an area for storing operation data, that is, a backup surface 16A.

As shown in FIG. 3, the block management table of the flash memory 15 includes the nonvolatile surfaces 15A,
The status of the writing status and the erasing status of 5B is stored. That is, 00 of the block management table of each surface 15A, 15B
The write status is stored from address (upper) to 01 (lower), and the erase status is stored from address 02 (upper) to address 03 (lower). In the writing situation, the upper part is FF and the lower part is FF
Is unused (invalid), the upper part is FF and the lower part is 0
A value of 0 indicates that writing is in progress (invalid), and an upper value of 00 indicates that writing is complete (valid). Also, in the erase situation, the upper part is FF and the lower part is FF.
Indicates that the erasure has not been processed (invalid), the upper 00 indicates that the erasure is in progress (invalid), and the lower 00 indicates that the erasure has been completed. ing.

The CPU 7 sets "under erasing" in the block management table before starting erasing, and sets "erasing completed" after erasing is completed. In addition, “writing in progress” is set before the writing of the operation data is started, and “writing completed” is set when the writing is completed. Thereby, for example, even when the power is cut off during the writing process and the erasing process,
By looking at the block management table when the power is turned on next time, it is possible to easily determine which surface of the operation data is normal and which surface of the operation data is being processed. Also, if an error occurs during the writing and erasing processes, the status of the writing status and the erasing status are not set to “completed”, and the process is interrupted in the middle of the next process for some reason. Then, it is possible to try writing and erasing again. Thereby, the CPU 7
It is possible to determine whether the operation data is normal or not for each of the surfaces 15A and 15B, and it is possible to restore the normal data by copying the normal operation data to the surface determined to be abnormal. Become.

When the operation data is changed, the first nonvolatile surface 15A, the second nonvolatile surface 15B, and the backup surface 16
Rewrite all three sides of A. FIG. 4 shows the operational data rewriting procedure. In FIG. 4, P data and Q data each indicate an operation data name. For example, before the operation data is rewritten (procedure A1), P data is written on each of the first non-volatile surface 15A, the second non-volatile surface 15B, and the backup surface 16, and the Q data is rewritten.
Indicates that it will be data. Next, FIGS. 4 and 5
Referring to the operational data rewrite flowchart shown in
The operation of the storage method using the flash memory of this example will be described. First, rewriting when the operation data is changed will be described. When rewriting the operation data, first, the operation data is written into the backup surface 16A of the backup RAM 16 (step S1). As a result, the operation data of the backup surface 16A becomes Q data (procedure A
2). After the writing, data for determination (hereinafter referred to as ID data) used for determining whether or not the backup has been performed normally is written. As the ID data, for example, control characters such as ABCD in ASCII code are used.

Next, a checksum (check total) is calculated for all data, and the checksum is written in a predetermined area in the backup surface 16A. Here is the checksum
The operation data stored in the backup RAM 16 is 1
It is the result of byte unit addition. Thus, the rewriting of the backup surface 16A is completed (Step S2). As the following procedure, the operation data of the backup surface 16A is copied to the nonvolatile surfaces 15A and 15B of the flash memory 15. First, as a preliminary process for writing operation data to the first nonvolatile surface 15A, an erasing process of the first nonvolatile surface 15A is performed as shown in a procedure A3. First, the first non-volatile surface 1
“Under erasing” is written into the block management table of 5A (see FIG. 3), and then the erasing process of the first non-volatile surface 15A is executed. When the erasing process is completed, “erase completed” is written in the block management table of the first nonvolatile surface 15A (step S).
3).

Next, the CPU 7 determines whether or not an access failure (failure of writing or erasing) has occurred (step S4). If there is no access failure (NO), the CPU 7 shifts to step S5 and operates. A process of writing data to the first nonvolatile surface 15A is performed (procedure A4). When writing the operation data, first, “writing” is written in the block management table of the first nonvolatile surface 15A, and then the backup surface 16A is written first.
Is written in the area of the first nonvolatile surface 15A and written. When the writing is completed, “writing completed” is written in the block management table of the first nonvolatile surface 15A. Thus, the rewriting process of the first nonvolatile surface 15A is completed. First
When the writing process of the non-volatile surface 15A is completed, step S
As in the case of No. 3, erasing is performed as a preliminary process for writing operation data to the second nonvolatile surface 15B. First, "under erasing" is written in the block management table of the second nonvolatile surface 15B. Subsequently, the second nonvolatile surface 15B is erased. When the erasing is completed, "erasing completed" is written in the block management table (step S6, procedure A5).

Next, the CPU 7 determines whether there is an access failure (writing or erasing failure) (step S).
7) If there is no access failure, the process proceeds to a process of writing Q data to the second nonvolatile surface 15B. The processing procedure is the same as that for writing to the first non-volatile surface 15A, and after writing “writing” in the block management table of the second non-volatile surface 15B, the Q data written to the backup surface 16A is stored in the second non-volatile surface 1A.
Copy and write to area 5B. When the writing is completed, “writing completed” is written in the block management table of the second nonvolatile surface 15B, and the rewriting process of the second nonvolatile surface 15B is completed (step S8, procedure A6). If a write error or an erase error is detected in step S4, it is not necessary to execute the write processing of the first non-volatile surface 15A in step S5.
The non-volatile surface 15B is erased. Step S7
In the case where a writing error or an erasing error is detected, the rewriting process is immediately terminated because it is not necessary to execute the writing process for the second nonvolatile surface 15B in step S8.

In general, in the end device as shown in FIG. 1, that is, in the end device of this example, the operation of the device is performed by using the operation data in the backup RAM 16.
Therefore, when the secondary battery 18 is completely discharged, it is necessary to copy the data from the first non-volatile surface 15A of the flash memory 15 to the backup surface 16A and restore the flash memory 15. Also, for example, the first memory of the flash memory 15
If the power supply 12 is cut off during the processing of the non-volatile surface 15A, or if the first non-volatile surface 15A
If the rewriting process of the backup fails,
6A, the operation can be continued. However, in consideration of the case where the secondary battery 18 is completely discharged in this state, the backup surface 16 is operated at a certain timing.
It is necessary to copy the operation data of A to the non-volatile surface. Hereinafter, the control procedure in this case will be described with reference to the flowchart of FIG.

As shown in FIG. 6, when the power is turned on, first, the validity of each of the first nonvolatile surface 15A, the second nonvolatile surface 15B, and the backup surface 16A is checked (step S1).
0). Whether the backup surface 15A is valid or not is determined based on the fact that the operational data can be read normally and the checksum matches the calculated value. In addition, the nonvolatile surfaces 15A, 1
Whether or not 5B is valid is that each state of the block management table is “writing completed”, “erasing completed”, and the state in which the operational data can be read normally, and the checksum matches the calculated value. Is the case. The highest priority valid surface serving as a copy source among the surfaces determined to be valid is designated as a backup surface 16A.
> The first nonvolatile surface 15A is determined according to the priority order of the second nonvolatile surface 15B. The reason for setting such priorities is that the latest data is always stored as long as the backup surface 16A is valid.

When the top priority effective surface is determined, all the data on the surface is copied to the other surface. In order to reduce the number of times of writing to the flash memory 15 as much as possible, it is determined whether or not to copy. I do. If the surface is valid and the checksum is the same as the highest priority valid surface, it is determined that exactly the same data has been normally written, and no copying is performed. From the above determinations, the top priority valid side and the copy permitted side are determined. Note that the above determination and determination are all performed by the CPU 7. Next, it is determined whether or not there is a copy-permitted surface that has not been rewritten (step S1).
1) If not, end. If there is an unprocessed copy-permitted surface, it is determined whether the surface to be written is a flash memory (step S12), and if YES, the process proceeds to step S1.
Proceed to 3. Thereafter, the operation data of the top priority side is sequentially copied on the copy permission side in the same rewriting procedure as the operation data.

That is, as a pre-process for writing operation data to the copy permitted surface, "erasing" is written in the block management table of the copy permitted surface, and then the copy permitted surface is deleted. "Erase completed" is written in the management table (step S13). Next, the process shifts to step S14 to perform a process of writing the operation data of the highest priority effective surface into the copy permitted surface of the flash memory 15. When writing operation data, first, "writing" is written in the block management table, and then all data written in the copy source is copied and written in the area of the copy permitted surface. When the writing is completed, "writing completed" is written in the block management table, and the rewriting process of the copy permitted surface of the flash memory 15 is completed.
Thereafter, the process returns to step S11 to repeat the above operation.

In step S12, if the surface to be written is not the flash memory 15, that is, if the backup R
If it is AM16, a process of writing the operation data of the highest priority valid side to the copy permission side (backup side 16A) is performed (step S15), and a checksum of the written operation data is calculated (step S16). It is determined whether or not the checksum of the data and the checksum of the highest priority valid face match (step S17). If they do not match, the process is repeated until they match, and if they match, the checksum is written (step S18). Thereafter, the flow returns to step S11 to repeat the above operation. By performing these procedures, even if the secondary battery 18 is completely discharged, or if a power failure or the like occurs during the change of the operation data, the operation data can always be restored and normal operation can be continued. It becomes possible.

Although the embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and there are design changes and the like that do not depart from the gist of the present invention. Is also included in the present invention. For example, in this embodiment, an example is described in which the storage method using the flash memory 15 is used for a portable terminal. However, for example, a personal computer, various communication devices, or the like retains data even when data is changed during operation. It is applicable to all devices that handle data that must be done.

[0026]

As described above, according to the present invention, two areas of a flash memory and a backup R
Since data is stored in a total of three areas including one area of AM, even if a writing error or an erasing error occurs due to a power failure or an external factor during rewriting, the operation data will be lost. It can be restored by copying it to the surface where processing has been interrupted, and in any case, normal operation data can be retained and operation can be continued . Further, a flash memory can be used instead of the conventional EEPROM as a storage medium for data to be held, and the cost can be reduced and the mounting area can be reduced by deleting the EEPROM.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an electrical configuration of a portable terminal to which a storage method using a flash memory according to an embodiment of the present invention is applied.

FIG. 2 is a conceptual diagram showing an operation data storage area of a flash memory and a backup RAM used in the storage method.

FIG. 3 is a diagram showing a block management table set in the flash memory.

FIG. 4 is a diagram for explaining the operation of the embodiment, and is a diagram showing a procedure for rewriting operation data.

FIG. 5 is a flowchart showing an operation processing procedure of the operation data rewriting.

FIG. 6 is a diagram for explaining the operation of the embodiment;
13 is a flowchart illustrating a processing procedure immediately after N.

[Explanation of symbols]

3 Control Unit 7 CPU 14 Address Data Bus 15 Flash Memory 15A First Nonvolatile Surface 15B Second Nonvolatile Surface 16 Backup RAM 16A Backup Surface 70 Recording Medium 72 Flash Memory Control Program (Storage Control Program) 73 Backup RAM Control Program (Storage) Control program)

Claims (7)

[Claims] 1. A flash memory having an area for storing data on a first nonvolatile surface and a second nonvolatile surface, a backup RAM having a backup surface, and backed up by a secondary battery. And storing data in a total of three areas including the first nonvolatile surface, the second nonvolatile surface, and the backup surface. 2. The data stored in the flash memory and the backup RAM includes a checksum obtained by adding the data in units of one byte and determination data for determining whether or not the data has been destroyed. 2. A storage method using a flash memory according to claim 1, wherein: 3. When rewriting data, data is rewritten in the order of the backup surface, the first non-volatile surface, and the second non-volatile surface, and the old data before rewriting is completed until the rewriting of the second non-volatile surface is completed. 3. A storage method using a flash memory according to claim 1, wherein data or new data after rewriting is present in said flash memory. 4. The first non-volatile surface and the second non-volatile surface include an area for storing a block management table, and the block management table includes an area for storing the first non-volatile surface or the second non-volatile surface.
4. The flash memory according to claim 1, wherein at least one of a state of writing / writing completion / writing non-execution / erasing / erasing completed / erasing not performed on the nonvolatile surface is written. Storage method using. 5. The validity of each of the first non-volatile surface, the second non-volatile surface, and the backup surface is confirmed, and among the surfaces determined to be valid, the highest priority valid surface serving as a copy source is determined as the backup surface. The first non-volatile surface is determined in accordance with the priority order of the second non-volatile surface, and a copy-permitted surface is determined under the condition that the highest priority valid surface does not match the checksum. 5. A storage method using a flash memory according to claim 1, wherein only operation data is copied. 6. The flash memory, wherein the flash memory and the backup RAM are connected to a CPU of a control unit of the mobile terminal via an address data bus, and the data is operation data of the mobile terminal. Memory method. 7. A recording medium on which a storage control program for causing a computer to function as a storage method using the flash memory according to claim 1 is recorded.