JPH11149419A - Method and device for backing up data - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for backing up data with which the data can be properly backed up even when a power source is turned off while data are written in a non-volatile memory. SOLUTION: This device is provided with an EEPROM 104 as the non-volatile memory, a CPU (data processing means) 103 for processing data in the EEPROM 104 while accessing these data, power source 101, a power source OFF detecting circuit 102 for detecting the interruption of power supply from the power source 101 to the CPU 103 and EEPROM 104, and a capacitor 105 for supplying power to the CPU 103 and EEPROM 104 in the period from the interruption of power supply to at least the end of data writing into the EEPROM 104 through the CPU 103.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data backup method and apparatus for backing up data when power is shut off, and more particularly to a data backup method and apparatus which can correctly restore data even if power is shut off while writing data to a nonvolatile memory. The present invention relates to a data backup method and device capable of performing backup.

[0002]

2. Description of the Related Art As a conventional data backup device (first conventional example), for example, there is one as shown in FIG.
In FIG. 1, a conventional data backup device is RA
M204, a CPU 203 that processes data while accessing the data in the RAM 204, and a main power supply 2
01, a backup power supply 205 such as a battery, a power cutoff detection circuit 202 for detecting that the power supply 201 is cut off, a power supply 201 or the backup power supply 20.
5 and the RAM 204 and the CPU 203
And a power supply selection circuit 206 for supplying power to the power supply.
In such a first conventional data backup device,
When the cutoff of the power supply 201 is detected by the power cutoff detection circuit 202, the power supply is switched from the power supply 201 to the backup power supply 205 by the power supply selection circuit 206, and the CPU 203 and the RAM
Power is supplied to the power supply 204 from the backup power supply 205. The power shutdown detection is also transmitted to the CPU 203, and the CP
The data is backed up to the RAM 204 from U203. However, in the data backup device of the first conventional example, a backup power source 205 such as a battery is used.
Because of the use of the above, there is a problem that maintenance is required and cost is increased. In order to deal with such a problem, a writable nonvolatile memory such as an EEPR is used as in the data backup device of the second conventional example shown in FIG.
There has also been proposed an apparatus in which maintenance of a backup power supply is not required by using an OM, a flash memory, or the like, and the cost of the apparatus is reduced. In the data backup device of the second conventional example, data is backed up to the EEPROM 304 every time a request for data change or the like is made while the CPU 303 is operating by power supply (not shown).

[0003]

However, in the data backup device of the second conventional example, the CPU
The data backup is performed irrespective of the interruption of the power supply to the non-volatile memory. Therefore, if the power supply is interrupted while the data is being written to the nonvolatile memory, there is a problem that the data cannot be properly backed up. The present invention has been made in view of the above-described conventional problems, and even when the power is shut off while writing data to the nonvolatile memory,
It is an object of the present invention to provide a data backup method and apparatus capable of correctly backing up data without breaking the data.

[0004]

In order to solve the above problems, a data backup method according to a first aspect of the present invention includes a nonvolatile memory and a power storage means, while accessing data in the nonvolatile memory. In the data backup method of the data processing means for processing the data, a power storage step of storing power from the power supply to the power storage means, a power cutoff detection step of detecting that power to the nonvolatile memory and the data processing means has been cut off, Supplying the power from the power storage unit to the nonvolatile memory and the data processing unit after the power interruption is detected until at least data writing to the nonvolatile memory by the data processing unit is completed; It is provided with. Further, in the data backup device according to the present invention, the nonvolatile memory, the data processing means for processing the data while accessing the data in the nonvolatile memory, and the power supply to the nonvolatile memory and the data processing means are shut off. Power cut-off detecting means for detecting that
A temporary backup for supplying power to the nonvolatile memory and the data processing means from the power storage means until power is stored by the power supply and at least until the data writing of the data processing means to the nonvolatile memory is completed after the power supply is cut off. Means. In the data backup method and apparatus according to the present invention, while power is supplied, the power is stored in the power storage means (power storage step), and the power to the nonvolatile memory and the data processing means is cut off by the power cut-off detection means. When the power-off is detected (power-off detection step), after the power-off is detected, at least until the data writing to the non-volatile memory by the data processing means is completed, the non-volatile memory and the data processing means are used by the power storage means. (Supply step). As a result, even if the power is shut off while writing data to the nonvolatile memory,
Since the data writing operation is continued by the power storage means,
Data can be backed up correctly without destroying the data.

[0005]

Embodiments of a data backup method and apparatus according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a configuration diagram of a data backup device according to an embodiment of the present invention. In the figure,
The data backup device according to the present embodiment includes an EEPROM 104 as a nonvolatile memory, and a CPU that processes data while accessing the data in the EEPROM 104.
(Data processing means) 103, power supply 101, power supply 10
A power cutoff detection circuit 102 for detecting that power to the first CPU 103 and the EEPROM 104 has been cut off;
After the power is stored by the power supply 101 and the power supply is cut off, the CPU 103 and the EEPROM 103 at least until the CPU 103 finishes writing data to the EEPROM 104.
A capacitor 105 for supplying power to the ROM 104,
A diode 106 for selecting the power supply of the capacitor 105,
107 and 108 are provided. In the data backup device of the present embodiment, usually, the power supply 10
1 is supplied to the CPU 103 via the diode 107.
When the CPU 303 is in operation, and there is a request for data change or the like, the
Data backup to the ROM 304 is performed. Also, during this normal operation, the power supply 101 supplies the diode 10
6 and is also supplied to the capacitor 105, and stored in the capacitor 105. Next, when the interruption of the power supply 101 is detected by the power interruption detection circuit 102, the fact is notified by the CPU.
103 is notified. At this time, the CPU 103 first confirms whether or not data has been written to the EEPROM 304 to back up the data. If the data has not been written, the CPU 103 terminates the process without backing up new data. I do. In addition, EEPROM3
When data writing to the EEPROM 104 is performed, the data is temporarily supplied to the CPU 103 and the EEPROM 104 by the capacitor 105 until the data writing to the EEPROM 304 by the CPU 103 is completed, and the data writing operation is continued. Then, after the data write operation is completed, the processing is terminated. Here, the capacitor 10
From FIG. 5, while the CPU 103 and the EEPROM 304 are being driven, the capacity of the capacitor 105 can be further reduced by setting the low power consumption mode including other components such as the I / O. For example, 5 [V]
A voltage of 2.5 [V] or more is applied for 20 [msec] by the power supply.
In order to maintain the above, when the current consumption is 1 [mA], the capacitance of the capacitor 105 may be about 12 [μF], and it is sufficient to prepare a small-capacity capacitor. In this embodiment, the nonvolatile memory is an EEPROM 30.
4, but the present invention is not limited to this, and it is also possible to realize it with a flash memory or the like.

[0006]

As described above, according to the data backup method and apparatus of the present invention, while power is being supplied, the power is stored in the power storage means (power storage step), and the power cutoff detection means is provided. When it is detected that the power to the nonvolatile memory and the data processing means has been cut off (power cut-off detecting step), at least until the data processing means finishes writing data to the nonvolatile memory after the power cut-off is detected. During this time, the power storage means temporarily supplies the data to the nonvolatile memory and the data processing means (supply step). Therefore, even if the power is shut off during the data writing to the nonvolatile memory, the data writing operation is continued by the power storage means. Data backup method that can back up data correctly without data corruption It is possible to provide a backup unit.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a data backup device according to an embodiment of the present invention.

FIG. 2 shows a conventional data backup device (first conventional example).
FIG.

FIG. 3 shows a conventional data backup device (second conventional example).
FIG.

[Explanation of symbols]

101, 201 power supply 102, 202 power cut-off detection circuit (power cut-off detection means) 103, 203, 303 CPU (data processing means) 104, 304 EEPROM (non-volatile memory) 105 capacitor (power storage means) 106, 107, 108 diode 204 RAM 205 Backup power supply 206 Power supply selection circuit

Claims (2)

[Claims] 1. A data backup method for a data processing unit, comprising: a non-volatile memory; and a power storage unit, wherein the data processing unit processes data while accessing the data in the non-volatile memory. A power cutoff detecting step of detecting that power to the nonvolatile memory and the data processing means has been cut off, and after the power cutoff is detected, at least the data writing to the nonvolatile memory by the data processing means ends. Supplying power to the non-volatile memory and the data processing means from the power storage means until the power storage means. 2. A non-volatile memory; a data processing means for processing data while accessing data in the non-volatile memory; and a power cutoff detecting that power to the non-volatile memory and the data processing means is cut off. Detecting means for storing power by the power supply and supplying power from the power storage means to the nonvolatile memory and the data processing means at least until the data processing means finishes writing data to the nonvolatile memory after the power supply is cut off; And a temporary backup means for performing a backup operation.