JPH04287143A - Data storage device - Google Patents

Abstract

PURPOSE:To enable backup without losing a latest data by generating an alarm signal by backing up the data in another non-volatile memory when write from a CPU reaches the limited number of times. CONSTITUTION:Normally, a data (system parameter) to be stored and the number of times for write are stored in respective areas 4 and 5 of a first non- volatile memory 1 by a CPU 3. When it is detected that the number of times for write read out from the write time number area 5 of the non-volatile memory 1 reaches the limited number of times, the data is written in a second non-volatile memory 2 and it is reported to an outside operator by generating the alarm signal that the exchange of the first non-volatile memory is required. Therefore, the latest data is held in the non-volatile memory 2 in place of the non-volatile memory 1. Further, when the non-volatile memory 1 for data storage is exchanged, the write is returned to be original.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to data storage devices, and more particularly to devices for storing data in non-volatile memory.

[0002] Multiplex transmission equipment etc. need to store data as various system parameters such as when power is turned on within the equipment, and these data are saved even when the power to the equipment is turned off. There is a need.

EEPROM (EEPROM) is generally used as a non-volatile memory to save data even when the power is turned off.
Electrically Erasable and
Programmable Read Only Me
Generally, EEPROM deteriorates in proportion to the number of electrical writes. This is EEP
There are defects in the silicon dioxide insulating layer that makes up the ROM, and the silicon dioxide is damaged in proportion to the number of times data is written from "1" to "0" and from "1" to "0". As electron injection progresses into the insulating layer and the number of writes reaches, say, 10,000 times, carrier mobility decreases and eventually a state is reached where current flows constantly, and the data is always "0". ”.

[0004] Therefore, when storing data,
It is necessary to constantly monitor the number of times the EEPROM is written.

[0005]

2. Description of the Related Art FIG. 3(a) shows a conventional data storage device using an EEPROM.
It is composed of OM1 and CPU3, and its operation is shown in the same figure (b).
As shown in FIG.
The current number of writes ("0" at the time of the first write) is read from the write number area provided in M1 (S2), and it is determined whether this is less than the limit number of times (S3).

As a result of this determination, if it is determined that the number of times is less than the limit, data is written to the data area of EEPROM1 and the number of times of writing read out above is set to "1".
The write count incremented by 1 is written in the write count area (S4).

On the other hand, as a result of the determination in step S3, if it is determined that the limit number of times has been exceeded, a ``write limit number of times exceeded alarm'' is reported to an external device connected to the CPU 3 (step S50). As a result, the operator who hears this notification determines that the EEPROM 1 has reached the end of its service life and takes measures such as replacing the EEPROM 1.

[0008]

Problems to be Solved by the Invention As described above, in conventional data storage devices, EEP as a non-volatile memory
When the ROM reaches its limit and is judged to have reached the end of its lifespan, it is replaced with a new EEPROM, so at the time of replacement, no data is written to the new EEPROM and the latest data is lost. Therefore, there was a problem in that the original purpose of EEPROM, which is a non-volatile memory, could not be achieved.

Accordingly, an object of the present invention is to realize a data storage device that can retain the latest data even when the number of writes to a nonvolatile memory reaches the limit number of times.

0010

[Means for Solving the Problems] Fig. 1 is a diagram explaining the principle of a data storage device according to the present invention for achieving the above object, in which (a) shows the circuit configuration, and (b) shows the processing sequence. 1, a first non-volatile memory 1 is used to store data as system parameters during normal operation, and has a data area 4 and a data writing frequency area 5. Further, 2 is a second non-volatile memory for backup to the first non-volatile memory 1, and has a data area 6 and an alarm area 7 used as necessary. Reference numeral 3 denotes a CPU for controlling data writing to these nonvolatile memories 1 and 2, and for generating an alarm signal as necessary.

[0011]

[Operation] The operation of the present invention will be explained with reference to FIG. 4 and 5 (steps S1 to S4 in the figure).

[0012] When it is detected that the number of writes read from the write number area 5 of the non-volatile memory 1 has reached the limit number (S3), data (system data) is stored in the second non-volatile memory 2. At the same time, an alarm signal is generated to notify an external operator that the first nonvolatile memory 1 needs to be replaced.

[0013] As a result, the latest data is held in the nonvolatile memory 2 instead of the nonvolatile memory 1.

Furthermore, in the present invention, at the same time as writing data to the second non-volatile memory 2, a "limit number of times exceeded alarm" can be stored in the alarm area 7 of the non-volatile memory 2. As a result, the CPU 3 refers to the "limit number of times exceeded alarm" in the alarm area 7 of the non-volatile memory 2 when turning on the power, etc., and retrieves data (system parameters) from any non-volatile memory.
It is possible to determine whether the data should be read or whether it can be written. Note that this "limit number of times exceeded alarm" is reset when the CPU 3 learns that the first nonvolatile memory 1 has been replaced.

[0015]

[Embodiment] FIG. 2 is a flowchart showing an embodiment of the processing operation of the data storage device according to the present invention shown in FIG. 1(a), and will be explained below with reference to FIG. 2(a). . In the present invention, EEPROMs 1 and 2 are used as both the first and second nonvolatile memories.

First, at the initial startup of the device, the EEP
Since it is not known whether the original data (system parameters) is stored in ROM1 or ROM2, first
The alarm area 7 in the PROM 2 is read (step T1 in the figure).

[0017] At this time, "limit number of times exceeded alarm"
If it is not set, the EEPROM 1 is within its lifespan, so the data is read from the data area 4 of the EEPROM 1 and its parameters are set in various devices (not shown) connected to the CPU 3. ).

In step T1, if the "limit number of times exceeded alarm" is set, it is determined that EEPROM 1 cannot be written to due to its lifespan, and the EEPROM is
The data is read from the data area 6 of No. 2, and its parameters are similarly set in each device (T3 of the same).

However, at this time, there is a possibility that the EEPROM 1 has been replaced, so the write count area 5 in the EEPROM 1 is read (T4) and it is determined whether or not it matches the limit number of times ( T5), if the result is a match, it is determined that the EEPROM 1 has not been replaced with a new one, and the process proceeds to normal operation step S1 without performing any special processing, but the number of writes exceeds the limit. If they do not match, it is determined that EEPROM 1 has been replaced with a new one, and the data previously read from EEPROM 2 and the content ``number of writes = 1'' are stored in the EE.
Write to the data area 4 and write count area 5 of PROM1, and write to the alarm area 7 of EEPROM2.
The "limit number of times exceeded alarm" is reset (T6), and the process proceeds to normal operation step S1. .

[0020] Proceeding to step S1 and proceeding to operational operation,
When a write request to EEPROM1 or 2 occurs, first read the write count area 5 in EEPROM1 (the S
1) If the number of times is less than the limit (S3), data (system parameters) and "number of writes +1" are written in the data area 4 and number of writes area 5 of the EEPROM 1, respectively (S4).

On the other hand, if the number of times matches the limit in step S3, EEPROM1 is used instead of EEPROM1.
2 writes data (system parameters) to data area 6 and reports an alarm signal to an external device.
A flag for "limit number of times exceeded alarm" is set in the alarm area 7 (S5).

After hearing this alarm signal, the operator turns off the power, replaces the EEPROM 1, and starts up the apparatus. After this, the process will proceed to step T1 described above.

[0023]

As explained above, according to the data storage device of the present invention, two nonvolatile memories are provided, one of which is used for data storage, and when the number of writes from the CPU reaches the limit number of times, The configuration is configured to back up data to the other non-volatile memory and generate an alarm signal, and is also configured to restore the original data if the non-volatile memory used for data storage is replaced, so the latest data can be restored. It can be backed up without loss, and if the nonvolatile memory for data storage is replaced as appropriate, the latest data can always be held in either nonvolatile memory.

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining the principle of a data storage device according to the present invention.

FIG. 2 is a flowchart showing one embodiment of the processing operation of the data storage device according to the present invention.

FIG. 3 is a diagram explaining the principle of a conventional example.

[Explanation of symbols]

1 First non-volatile memory for data storage (EEPR
OM) 2 Second non-volatile memory for backup (EEP
ROM) 3 CPU In the diagram, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] Claim 1: Consisting of two non-volatile memories (1, 2) and a CPU (3), the first non-volatile memory (
1) is provided with an area (4) for data written by the CPU (3) and an area (5) for the number of data writes, and the second non-volatile memory (2) is provided with an area for data written by the CPU (3).
Data area (6) written by U(3)
The CPU (3) reads the number of writes when writing to the first non-volatile memory (1), and when the number of writes reaches the limit number, reads the number of writes to the second non-volatile memory (1). A data storage device characterized in that it writes data to a digital memory (2) and also generates an alarm signal. 2. A write limit number over alarm written in the second non-volatile memory (2) by the CPU (3) and reset when the first non-volatile memory (1) is replaced. The CPU (3) writes a write limit number over alarm in the alarm area (7) when the CPU (3) generates the alarm signal. Claim 1
A data storage device as described in .