JP2003140979A - Recording method to eeprom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording method to EEPROM, capable of writing without exceeding a write frequency limit of the EEPROM, and effectively using up the physical memory space of the EEPROM. SOLUTION: In this recording method to the EEPROM, the maximum write frequency for writing to the conventional memory is fixed as Nmax. The physical memory space of the EEPROM is previously divided in each area as a unit for simultaneous writing. The write frequency information for specifying the write frequency N to the area in writing in the memory in the area is simultaneously written in a memory with a first specified address in the area, whereby writing is performed to a memory in the other area keeping away from the area whose write frequency N obtained from the write frequency information of the first specified address in writing is Nmax or more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an EEPROM recording method. In particular, the present invention relates to an EEPROM recording method, which is characterized in that the property of the EEPROM that the number of times of writing is limited by the specifications is taken into consideration.

[0002]

2. Description of the Related Art EEPROM (Erectrically Erazable)
and Programmable Read Only Memory) is a read-only memory element that can be electrically erased and written. No special erasing device is required, and erasing and rewriting can be done with the system installed. In addition to storing programs, it is used not only to store system BIOS and bootstrap code, but also to store data of setting items that differ for each user environment.

Furthermore, it is lightweight and compact, and it is a device that exercises by utilizing the characteristics that are strong against vibration without having a mechanical part such as a hard disk, and is also used for data storage of an aircraft or the like which is particularly required to be lightweight and compact. The following methods are available as the recording method. (1) EEPROM as well as ordinary memory (RAM)
Each variable is allocated to the physical memory space of and the data is stored. (2) The physical memory space of the EEPROM is divided into a plurality of storage areas, the storage area is selected based on the header information, and the data is stored.

[0004]

In the case of the above-mentioned EEPROM recording method, in (1), only a partial area of the physical memory space of the EEPROM can be used. In (2),
Although it is possible to use the entire area of the physical memory space of the EEPROM, it is not possible to know how much space is left until the number of times the EEPROM is written is limited by the specifications. There is a risk of losing

The present invention has been devised in view of the above-mentioned problems. Instead of the conventional EEPROM recording method, writing is performed without exceeding the EEPROM write count limit, and the physical memory of the EEPROM is written. An attempt is made to provide a recording method to the EEPROM that can use up the space effectively.

[0006]

In order to achieve the above object, the EEPROM recording method according to the present invention, in which the maximum number of times of writing to the memory is defined as Nmax, is a method of simultaneously writing in the physical memory space of the EEPROM. The number of times of writing, which is divided into a plurality of areas which are units that can be performed in advance, and which specifies the number of times N of writing in the memory in the area is written in the memory of the first specific address in the area. When writing simultaneously and writing to the memory in the area, if the number N of writings obtained from the number-of-writings information of the first specific address in the area is Nmax or more, the writing is still performed. It is assumed that data is written in the memory in the other area which is not present.

According to the above-mentioned configuration of the present invention, Nmax is the maximum number of times of writing to the memory, the area is a unit in which writing can be simultaneously performed in the physical memory space of the EEPROM, and writing is performed in the memory in the area. At the same time, the write count information for specifying the write count N in the area is simultaneously written in the memory of the first specific address in the area, and the write count N is Nmax or more when writing in the memory in the area. Since the data is written in the memory in the other area while avoiding the above-mentioned area, the number of writing N does not exceed Nmax and the data in the memory in the area is not written.
It is possible to write to the memories in other areas that do not exceed max one after another.

Further, the recording method in the EEPROM according to the present invention defines a page which is a virtual memory space having a memory space which is the same as or smaller than the memory space of the area, and the area is allocated to each of the pages. Therefore, when the writing of the data to the page occurs, the writing is performed to the memory in the area allocated to the page. According to the configuration of the present invention described above, the page is a virtual memory space having the same or smaller memory space as the memory space of the area, the area is allocated to each of the pages, and writing of data to the page occurs. At this time, since data is written to the memory in the area allocated to the page, data is written to the physical memory space of one area allocated to the page or the physical memory space of the latest area of the plurality of areas. By doing so, the data that has been written to the page can be saved.

The EEPROM recording method according to the present invention prepares a management table in which one page is associated with the latest area in which data is written in the page in a one-to-one correspondence, and the data in the page is recorded. When the above writing occurs, the management table is referred to and the writing in the memory in the area associated with the page is performed. According to the configuration of the present invention, one page is associated with the management table in a one-to-one correspondence with the latest area in which data is written to the page, and the management table is referred to when data writing to the page occurs. Since the data is written in the memory in the area associated with the page, the latest area associated with the page can be immediately found by referring to the management table and the data can be written in the area.

Further, in the recording method in the EEPROM according to the present invention, the page identification code for identifying the page to which the area is allocated is written in the second specific address of the area. With the above-mentioned configuration of the present invention, since the page identification code for identifying the page to which the area is assigned is written in the second specific address of the area, the writing obtained from the page identification code and the first specific address From the number of times N, the latest area associated with the page can be found and data can be written to that area.

Further, in the EEPROM recording method according to the present invention, the date information for specifying the latest date of writing in the area is written in the third specific address of the area, and the past date is used by using the date information. In the case where writing is performed at the same frequency, the date on which the number of times N of writing in all areas can be the maximum number of times of writing Nmax or more is predicted. With the above configuration of the present invention, when the latest date information is obtained from the third specific address in the area and writing is performed at the same frequency as in the past using the date information, the number of writing times N in all areas is Since the date nearing the maximum write count Nmax or exceeding Nmax is predicted, the date when the EEPROM cannot be used can be roughly determined.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below with reference to the drawings. In each drawing, common portions are denoted by the same reference numerals, and redundant description will be omitted.

A recording method in the EEPROM according to the embodiment of the present invention will be described. FIG. 1 is a conceptual diagram of an embodiment of the present invention.

First, the EEPR according to the embodiment of the present invention.
An apparatus for implementing the OM recording method will be described. Figure 4
It is a conceptual diagram of the apparatus which implements embodiment of this invention. The device 1 includes a CPU 2, a program 3, a RAM 4 and an EEPRO.
It has M5 and I / O6. CPU2 is program 3
According to the measurement, the measurement data is temporarily stored in the RAM 4 and then recorded in the EEPROM 5. Program 3 is
This software represents the procedure for measurement and data storage. The program 3 has a data measurement routine and a data storage routine. The RAM 4 is a random access memory that temporarily stores measured data. EEPR
The OM 5 is an electrically rewritable read-only memory that stores measured data. The I / O 6 is connected to the sensor 7 and takes in desired measurement data.

FIG. 1 is a memory space diagram of an embodiment of the present invention. The memory space includes a page space 100, a data recording space 300, and a management table 200. The page space 100 is a virtual memory space, and the data measurement routine of the program 3 writes to and reads from this page space 100. The page space 100 has a plurality of pages 101, 102, ...
.. have a unique identification code. here,
For convenience of explanation, the identification codes are page 1, page 2, ... Each page 101, 102 ...
It has a space that can store the number of data that is suitable for the convenience of measurement. The data measurement routine uses a specific page 10
When a write command or a read command is issued to 1, 102 ...
The data recording space 200 referred to by is written or read.

The data recording space 300 has an EEPROM 5
It is provided in the physical memory space of. Data recording space 30
0 is composed of a plurality of areas 310, 320 ...
Here, the areas 310, 320, ... Are EEPROMs.
5 is a unit in which writing can be performed simultaneously in the physical memory space. The area may be a minimum unit capable of simultaneously writing in the physical memory space of the EEPROM 5, or may be a combination of a plurality of minimum units. Areas 310, 320 ...
Has a unique identification code. Here, for convenience of explanation, it is assumed that area 0, area 1, ... Each area 310, 320, ... Has one management area and one data area. The management area is an area for storing management data for carrying out a recording method in the EEPROM 5, which will be described later, and an area 311 for storing a page number (hereinafter referred to as a page number area 311) and an area for storing the number of writes. It has an area 312 (hereinafter referred to as a write count area 312) and an area 313 for storing date information (hereinafter referred to as a date area 313). The data area 314 ... Is a memory area for storing measured data.

The page number area 311 has an area 31.
It is a memory space for storing the page number assigned to 0 (corresponding to the area of the second specific address). Initial value is N
In the case of the ULL, when the area is allocated to a specific page by a predetermined procedure, the allocated page number is written in the memory write processing routine in the area immediately after that. Write count area 3
Reference numeral 12 denotes a memory space (corresponding to the area of the first specific address) that stores the number of times writing processing has occurred in the memory in the area. The initial value is NULL, and when the writing process occurs at the memory address in the area, the code stored in the writing count region is incremented and writing is performed in the writing process routine. The date area 313 is a space for storing the date of the latest date when the writing process occurred in the memory address in the area (corresponding to the area of the third specific address). The initial value is NULL, and the date held by the internal timer of the CPU is written in the same write processing routine in which writing has occurred in the write count area. Where NUL
L is a specific code defined by the system, for example,
It is "FFFF".

The management table 200 is placed in the memory space of the RAM 4. In some cases, the aforementioned EEPROM
It may be provided in the physical memory space 5. Management table 2
00 is a look-up table for referring to the areas 310, 320, ... Allocated to the pages 101, 102. For example, the identification code of the area allocated to each page is arranged in ascending order of the identification code of the page, starting from the specific RAM address. Areas are assigned to each page by a predetermined procedure.

Next, EEPRO according to the embodiment of the present invention
A memory storing routine for implementing the recording method in M will be described. FIG. 3 is a flowchart of the embodiment of the present invention. FIG. 2 is a state transition diagram of the memory according to the embodiment of the present invention. The memory storing routine is the write routine S1.
0, a read routine S20, and a memory full date prediction routine S30.

The write routine S10 will be described according to the flow. When a write command to a desired page in the virtual memory space 8 occurs, the write routine S10
Will start. Hereinafter, for convenience of description, it is assumed that a write command is generated on page 2. <S11: Page Designation> The code “page 2” of the page requested to be written is confirmed. <S12: Area search> Referring to the management table 200,
Check the area to which "Page 2" is assigned.
For example, "area 1" is assigned to "page 2". <S13: Area writing> Data is written in the data area of "Area 1". <S14: Increment write count> A value obtained by adding 1 to the number stored in the write count area of "Area 1" is stored as a new count in the write count area.

<S15: Nmax? > Check whether the number written in the write count area has reached Nmax. If not reached, the write routine ends. Here, Nmax is a number determined based on the guaranteed number of times of writing in the specifications of the EEPROM, and for example, Nmax = 50,000 times with respect to the guaranteed number of times of writing = 100,000 times. If so, proceed to the next. <S16: Allocate a new area> According to the predetermined procedure,
Allocate an area that has never been allocated to "Page 2". For example, “area 43” is assigned. The code stored in the page number area and the write count area of the "area 43" is NULL. "Page 2" is written in the page number area of "Area 43", "1" is written in the write count area, and the date of the timer is written in the date area. <S17: Data Transfer to New Area> All data stored in the data area of the area is transferred to the data area of the new area. <S18: Update Management Table> The area number where the page area number of the management table 100 is stored is changed to a new area number. For example, the area number "page 43" is stored in "area number of page 2".

Next, the read routine S20 will be described according to the flow. When a read instruction for a desired page in the virtual memory space 8 is issued, the read routine S2
0 starts. Hereinafter, for convenience of description, it is assumed that a write command is generated on page 2. <S21: Page Designation> The code "page 2" of the page requested to be read is confirmed. <S22: Area search> Referring to the management table 200,
Check the area to which "Page 2" is assigned.
For example, the following description will be made assuming that "area 43" is assigned to "page 2". <S23: Area Read> Data is read from the allocated area. For example, desired data is read from the data area in "area 43".

Next, the memory life prediction routine S30 will be described according to the flow. <S31: Confirm the number of used areas> Of the total areas,
The number of areas in which the number stored in the write count reaches Nmax and the number of remaining areas are confirmed. <S32: Confirm latest date> Among the dates in which the dates in the total area are stored, the latest date and the oldest date are confirmed. <S33: Life Prediction> From the number of remaining areas and the date,
A date when the number of writings in all areas becomes Nmax is predicted by extrapolation.

If the EEPROM recording method of the above-described embodiment is used, data can be stored in the EEPROM by effectively utilizing the entire memory space area of the EEPROM without exceeding the allowable number of times of writing in the EEPROM. Further, when the measurement routine writes or reads data in a page which is a virtual memory space, it is possible to write or read data in a memory storage routine which is a physical memory space, which facilitates designing and modifying the measurement routine. Moreover, since the management table in which the relation between the page and the area is recorded in advance is used, the memory storing routine writes at a high speed,
It can be read. Also, since the code of the page assigned to the specific address of the area is recorded,
By tracing this data when starting the measurement system,
The management table can be generated, and it is not necessary to prepare a volatile memory backed up to store the management table. Also, since the date of writing is written in the area, it is possible to easily predict the date when the area will be used up.

The present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention. If the management table is described as being in the RAM, the present invention is not limited to this and may be in the EEPROM.

[0026]

As described above, the maximum number of times of writing to the memory of the present invention is set to Nmax and E
The EPROM has the following effects due to its configuration.
The number of times of writing N does not exceed Nmax and writing is not performed in the memory in the area, and the number of times of writing N is Nmax.
It is possible to write one after another to the memory of other areas that do not exceed. Also, by writing data to the physical memory space of one area allocated to the page or the physical memory space of the latest area of the plurality of areas,
You can save the data that has been written to the page. Further, it is possible to immediately find the latest area associated with the page by referring to the management table and write the data in the area. Further, the latest area associated with the page can be found from the page identification code and the number of times of writing N obtained from the first specific address, and the data can be written in the area. Also, EE
The date when the PROM becomes unusable can be roughly determined. Therefore, it is possible to provide a recording method to the EEPROM in which writing can be performed without exceeding the number of writing times of the EEPROM and the physical memory space of the EEPROM can be effectively used.

[0027]

[Brief description of drawings]

FIG. 1 is a memory space diagram of an embodiment of the present invention.

FIG. 2 is a state transition diagram of the memory according to the embodiment of the present invention.

FIG. 3 is a flow chart diagram of an embodiment of the present invention.

FIG. 4 is a conceptual diagram of an apparatus for implementing an embodiment of the present invention.

[Explanation of symbols]

1 Measuring device 2 CPU 3 programs 4 RAM 5 EEPROM 6 I / O 7 sensors 100 page space 101 page 1 Page 102 Page 103 3 Page 104 200 management table 201 Storage space for page 1 area number 202 Storage space for page 2 area numbers 203 Storage space for page 3 area numbers 204 Storage space for page 4 area number 300 data recording space 310 area 0 311 page number area 312 write count area 313 Date area 314-Data storage space 320 area 1 330 area 2 340 area 3 350 area 43

Claims (5)

[Claims] 1. A method of recording in an EEPROM in which the maximum number of times of writing to a memory is defined as Nmax, wherein a physical memory space of the EEPROM is pre-divided into a plurality of areas which are units in which writing can be performed at the same time. When simultaneously writing the number-of-times information for specifying the number N of times of writing to the memory in the area to the memory of the first specific address in the area and writing to the memory in the area In the case where the number of times of writing N obtained from the number of times of writing of the first specific address in the area is Nmax or more, writing is performed in a memory in another area that has not been written yet. A method for recording data on an EEPROM, which is characterized in that 2. A page that is a virtual memory space having a memory space that is the same as or smaller than the memory space of the area is defined, and the area is allocated to each of the pages, and writing of data to the page is performed. The E according to claim 1, wherein when the error occurs, writing is performed in the memory in the area allocated to the page.
Recording method to EPROM. 3. A management table is prepared in which one page is associated with the latest area in which data is written to the page in a one-to-one correspondence, and the management table is stored when data writing to the page occurs. 3. The EEPROM recording method according to claim 2, wherein the writing is performed in the memory in the area associated with the page with reference to the page. 4. The EEPROM according to claim 2 or 3, wherein a page identification code for identifying a page to which the area is allocated is written in a second specific address of the area. Recording method. 5. When the date information specifying the latest date of writing in the area is written in the third specific address of the area and the writing is performed at the same frequency as the past using the date information, all 5. The method for recording in the EEPROM according to claim 1, wherein a date at which the number of times N of writing of the area can be the maximum number of times of writing Nmax or more is predicted.