JP2001318836A - Method for managing data of non-volatile memory - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the probability of data destruction, and to make it possible to restore data. SOLUTION: Data on a non-volatile memory are copied on a volatile memory (RAM) and updated, and a check code is calculated, and the updated data on the RAM and the check code are written altogether on the non-volatile memory so that the data can be rewritten, and the data are stored in the different areas of the non-volatile memory so as to be backed-up. Moroever, a back-up area is arranged in the non-volatile memory, and at the time of rewriting the data, the data before rewriting are copied on the back-up area, and the back-up area is initialized under a condition that the updating is normally operated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data management method for a nonvolatile memory in an IC module having a nonvolatile memory used in a portable information processing device such as an IC card.

[0002]

2. Description of the Related Art First, the function of an IC card will be described as an example in which an IC module is loaded. As shown in FIG. 7, a command (command) is transmitted from a reader / writer 1 to an IC card 2, The IC card that receives the instruction interprets the instruction, executes processing such as writing / reading, and returns the processing result to the reader / writer 1 as a response.

As shown in FIG. 8, an IC card 2 has a CP
U11, RAM12, ROM13, nonvolatile memory 14
When a program stored in the ROM 12 is read into the CPU 11 and a command transmitted from the reader / writer 1 is received through the I / O port, the data transmitted with the command is read and the nonvolatile memory 14 is read.
It reads and processes the data stored in it, updates the data, and outputs a response to the reader / writer 1 through the I / O port.

When data is stored in a nonvolatile memory in an IC card, a check code for confirming data consistency is also stored in the memory in the same manner.
Then, before reading / writing data, the consistency with the check code is always checked. If the consistency is not obtained, the reading / writing is stopped, and an error has occurred in the data on the memory. To the reader / writer.

[0005]

Conventionally, when writing data to a memory such as new writing or partial updating of data,
The processing is divided into the following two stages. Write the data. A check code of the written data is calculated and written to a predetermined position. As described above, the data writing to the memory is performed twice, so if an event such as a power supply cutoff occurs between the processes, the data and its check code are matched. Sex is not maintained. In particular, in the case of a non-contact type IC card, there is a high possibility that the power supply to the reader / writer goes out of the radio wave range and is cut off. If the data and check code are not consistent, the data cannot be trusted,
In some cases, the reading / writing is stopped.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to reduce the probability of data destruction due to mismatch between data and a check code, and to restore data before the destruction.

[0007]

The present invention relates to a data management method in a nonvolatile memory used in an IC module mounted on an IC card or the like described with reference to FIGS. When storing data, the number of times of writing to the non-volatile memory is reduced to improve the processing speed, the probability of data destruction of mismatch between data and check code is reduced, and when data destruction is detected, It is designed to be able to restore the data before it was destroyed.

A data management method for that purpose will be described below. (A) When rewriting data in the nonvolatile memory,
The data in the non-volatile memory is temporarily copied to the volatile memory (RAM) and processed according to the following procedure. The data on the RAM is updated and a check code is calculated. Further, the calculated check code is stored in the RAM together with the data. The updated data on the RAM and the check code are collectively written into the nonvolatile memory, and the data is updated by a single write process. According to this method, since the data write processing is performed once, the update time of the data in the nonvolatile memory is halved as compared with the related art, and the probability of data destruction can be reduced. (B) The same data is stored in different areas of the nonvolatile memory to back up the data. The following two backup methods, a mirror function and a backup function, are used depending on the meaning of the data. For example, since the mirror function always has two identical data and is used for long data, a large memory capacity is required for long data. Therefore, the mirror function is applied to relatively short data, and the backup function is applied to long data. (B-1) Mirror Function (Always Duplicating the Same Data) If data consistency cannot be confirmed, the inconsistent data is corrected using backup data. If data consistency cannot be confirmed, the backup data is referred to. If the above or has occurred, when rewriting data, rewrite data in the order of “data area where inconsistency has occurred → data area with consistency”. Priority is given to reading unwritten data without rewriting as much as possible. (B-2) Backup function (using a specific work area on the memory) (a) Data writing method Before rewriting data on the nonvolatile memory, data (old data) is stored in the work area (backup area) of the nonvolatile memory. Copy New data in the RAM is copied from the RAM to the nonvolatile memory (write data area) to rewrite the data. Initialize the work area of the non-volatile memory to erase old data. (B) Data restoration method If the work area of the non-volatile memory is not initialized (old data remains), the data writing in (b) is not completed, so use the old data in the work area. Restore. If the work area of the nonvolatile memory has been initialized, nothing is performed. (C) The mirror function and the backup function shown in (b) can be used depending on whether the function is valid or invalid depending on the setting on the memory. Specifically, a flag area indicating valid / invalid is provided on the memory,
Prior to processing, validity / invalidity is determined with reference to this flag. This is because the mirror function requires a large amount of memory and the backup function requires a large number of rewrites, so that this function can be used or not used as necessary.

[0009]

Embodiments of the present invention will be described below. FIG. 1 shows a basic E in a nonvolatile memory.
FIG. 2 is a diagram illustrating a data structure of F (Elementary File), and FIG. 2 is a diagram illustrating an area structure of a nonvolatile memory. The data in the IC card is stored in the nonvolatile memory as an EF as shown in FIG. The directory information shown in FIG. 1 represents a collection of a pointer P indicating a data storage position (address), a file identifier, and the like, and is constituted by a block check code (BCC1) for maintaining the validity of this information. Data is stored in a system using an IC card.
The data is stored in a place where it is desired to be stored in the C card, and the stored data is a block check code (BCC2).
The legitimacy is maintained.

Normally, when an inconsistency occurs in the BCC2, the IC card uses a higher-level system (reader / writer in FIG. 7).
Sends back data with a warning that "data may be incorrect." If BCC1 is inconsistent, the value of the pointer cannot be guaranteed and an error that means "data is corrupted" is returned. I will send it back.

Accordingly, the memory area of the IC card has a structure as shown in FIG. At this time, the directory information of FIG. 1 is written into two places of the Primary area and the Secondary area of FIG. 2 to realize the mirror function. That is, Primar
Store the same directory information in two places, the y area and the secondary area, so that they can be backed up. Since the directory information is relatively short, a large amount of memory capacity is not required even if such two areas are used.

Further, when the data of FIG. 1 is stored in the write data area of FIG. 2 and the data is rewritten, the data is copied to a backup area prior to the rewriting, and
A backup function is realized by overwriting with data on the AM.

Next, a processing flow in the mirror function will be described with reference to FIG. This process is executed when accessing the directory information. First, the EF of the Primary area
(Step S1), and it is determined whether there is an EF (step S2). And when I discover EF,
It is determined whether or not y has a BCC error (step S
3). If there is no BCC error and the directory information is valid, it is copied onto the RAM (step S4). Then, the mirror function is confirmed (step S
5) If the mirror function is enabled, the Se
Calculate the address of condary (step S6), and then
It is determined whether there is a BCC error in Secondary (step S7). If there is a BCC error in Secondary, R
The data is copied from the AM to the Secondary to restore the data (step S8). If the mirror function is invalid in step S5, B is sent to Secondary in step S7.
If there is no CC error, the process returns and the RAM is referred to thereafter. In step S3, the BC is
If there is a C error, the primary BCC error flag is set (step S9), and in step S2, Pr is set.
If the imary EF could not be found, the Primary BC
The C error flag is cleared (step S10), and the mirror function is confirmed (step S11). If the mirror function is enabled, the secondary EF is searched (step S1).
2) It is determined whether there is an EF (step S13).
If there is no BCC error in Secondary, copy the directory information of Secondary to RAM (step S1).
5) The Primary address is calculated from the Secondary information, and the data is copied from the RAM to the Primary to restore the data (step S17). If the mirror function is invalid in step S11, EF is executed in step S13.
If no is found, in step S14 Seco
If there is a BCC error in the ndary, it is determined whether or not the Primary has a BCC error (step S18). If there is no BCC error (the flag is cleared in step S10), E is set.
F does not exist, and if there is an error, the directory information has been destroyed.

FIG. 4 is a diagram showing a processing flow of the mirror function. This process is performed when there is updated new data in the RAM and this is to be written to the memory. First,
Check the mirror function (step S21), and if it is valid,
Primary LRC (Longitudinal redundancy check)
It is determined whether there is an error (step S22). If there is no error and the Primary data is correct, the data in the RAM is written to the Secondary area and updated (step S23). Then, it is determined whether or not there is a write error in the secondary area (step S24). If there is no write error, since the correct data has been stored in the secondary, the primary area is also updated with the data in the same RAM (step S25). ). Also, even when the mirror function is invalid in step S21, the Primary area is updated with the data on the RAM. Further, it is determined whether or not there is a write error in the Primary area (step S26), and if not, the process ends normally (step S27). If there is an LRC error in the Primary in step S22, the data in the Primary is corrupted, so the Primary area is updated with the data in the RAM (step S28), and it is determined whether there is an error in writing to the Primary area (step S22). S29). If there is no write error, since the correct data is stored in the Primary, the Secondary area is also updated with the data on the same RAM (step S30). Then, it is determined whether or not there is a write error in the secondary area (step S3).
1) If not, end normally. Step S24,
If there is a write error in any of steps S26, S29, and S31, the process ends abnormally (step S32).

FIG. 5 is a diagram showing a processing flow of a data writing method in the backup function. This process
The address and length of the data to be backed up in the non-volatile memory are given as arguments. First, the backup function is checked (step S41). If the backup function is valid, the start address and length of the data to be stored are set in the RAM (step S42). Next, the data to be stored is copied to the RAM (step S43), and the LRC of the data copied to the RAM is obtained (step S44). Next, the backup data is written from the RAM to the backup area of the nonvolatile memory (Step S45), and it is determined whether or not there is a write error (Step S46). If there is no write error, or if the backup function is disabled in step S41, the data in the write data area is
Update with the data on the AM (step S47). At this time, it is determined whether or not there is a write error (step S4).
8) If not, check the backup function (Step S)
49), if the backup function is valid, the backup area is initialized (step S50);
If the backup function is invalid at 49, the process ends normally (step S51). Step S46, Step S4
If there is a write error in step 8, the process ends abnormally (step S52).

FIG. 6 is a diagram for explaining the processing flow of the data restoration method in the backup function. First, the backup function is checked (step S61).
It is determined whether the backup area is in the initialized state (step S62). If it is not in the initialization state, the data rewriting of the non-volatile memory has not been completed, so it is necessary to restore with the backup data. Therefore, it is determined whether or not there is an LRC error in the data remaining in the backup area (step S63). If there is no LRC error, the backup data is valid and is set in the RAM (step S64), and the LRC of the backup data is set.
Is calculated (step S65). Next, the data in the nonvolatile memory is rewritten with the backup data in the RAM (step S66). At this time, it is determined whether or not there is a write error (step S67). If there is no write error, the data in the data area of the nonvolatile memory has been restored, so the backup area is initialized. Step S6
1 when the backup function is disabled, and when the backup area is in the initialized state in step S62, step S63
When there is an LRC error in the backup area, and when there is a write error in step S67, the process ends.

[0017]

As described above, according to the present invention, when rewriting data in a non-volatile memory, the data in the non-volatile memory is temporarily copied to the RAM, and the data in the RAM is updated and checked. After calculating the code, the data was written to the non-volatile memory all at once.
The data can be updated in one writing process, and the update time of the data in the non-volatile memory is halved as compared with the related art, so that the probability of data destruction can be reduced. In addition, a mirror function for always duplicating the same data and a backup function for using a specific work area on a memory are provided. By properly using these functions, data before corruption can be restored.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a data structure of an EF in a nonvolatile memory.

FIG. 2 is a diagram illustrating an area of a nonvolatile memory.

FIG. 3 is a diagram illustrating a processing flow of a mirror function.

FIG. 4 is a diagram illustrating a processing flow of a mirror function.

FIG. 5 is a diagram illustrating a data writing method of a backup function.

FIG. 6 is a diagram illustrating a data restoration method of a backup function.

FIG. 7 is a diagram illustrating communication between a reader / writer and an IC card.

FIG. 8 is a diagram illustrating a configuration of an IC card.

[Explanation of symbols]

1 ... reader / writer, 2 ... IC card, 11 ... CPU,
12 RAM, 13 ROM, 14 nonvolatile memory,
P ... pointer.

Claims (7)

[Claims] When rewriting data stored in a non-volatile memory, the data in the non-volatile memory is copied to a volatile memory (RAM), updated, a check code is calculated, and the updated data in the RAM is calculated. And rewriting data by writing the check code and the check code together on the non-volatile memory. 2. The same data is stored in different areas of a non-volatile memory, and when data in one area becomes inconsistent, data in the other area is copied onto a RAM, and then the data on the RAM is copied. A data management method for a non-volatile memory, wherein data in which inconsistency has occurred is corrected by copying the data in an area in which inconsistency has occurred. 3. The data management method according to claim 2, wherein the data is directory information. 4. A backup area is provided in a nonvolatile memory, and when rewriting data in the nonvolatile memory, data before rewriting is copied to the backup area, and the data in the nonvolatile memory is updated with new data in the RAM. A data management method for a non-volatile memory, wherein a backup area is initialized on the condition that the operation is normally performed. 5. The data management method for a nonvolatile memory according to claim 4, wherein when the backup area is not initialized, the data in the nonvolatile memory is restored using the data in the backup area. 6. The data management method for a nonvolatile memory according to claim 4, wherein said data comprises relatively long data. 7. The nonvolatile memory according to claim 2, wherein a flag area for determining whether or not to execute the processing is provided, and the processing is executed on condition that the flag is set. Non-volatile memory data management method.