JPH05233474A - Storage contents protection system - Google Patents

Abstract

PURPOSE:To continuously perform stable data processing by making a power- source backup storage means hold the storage contents of a storage means for arithmetic which is not backed up by a power source even if electric feeding is stopped during a self-diagnosis. CONSTITUTION:An arithmetic processing part 1 detects a threshold level V1 during the processing of an S-RAM 4 including the self-diagnosis, gives top priority to the writing of the storage contents of the RAM 3 (power-source non-backup arithmetic storage means) to the S-RAM 4 (power-source backup storage means) which is backed up by a power source whatever operation is performed if an interruption is initiated, and performs the writing to the S-RAM 4 in a time(t) of several mS of a voltage drop from the threshold level V1 to a threshold level V2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a storage content protection system used for a microprocessor in a data processing device such as a computer.

[0002]

2. Description of the Related Art Conventionally, a data processing device such as a computer employs a software memory switch. An EEPROM or a RAM whose power is backed up is used for this memory switch, and the stored contents are retained even after the power supply to the device is stopped.

By the way, in a data processing device using a microprocessor, self-diagnosis is performed. This self-diagnosis is performed together with the arithmetic processing unit (CPU) by I / O, ROM, RAM for memory switch (in the sentence, S-RAM if necessary
Will be described). In this case, as shown in FIG. 3, S- is stored in the non-power backup arithmetic RAM of the arithmetic processing unit.
The memory contents of the RAM are stored, test data is written to the S-RAM, and then read to confirm the normal operation of the S-RAM. After this self-diagnosis, the contents stored in the calculation RAM are written again in the S-RAM.

[0004]

By the way, in the conventional memory content protection system, during self-diagnosis, that is, S-RAM.
Stored in the calculation RAM, write test data in the S-RAM, and if energization stops during reading after that, the stored content in the S-RAM disappears and continuous and stable data processing is performed. There is a drawback that you cannot do it.

The present invention is intended to solve such a problem, and the contents stored in the non-power-supply backup calculation storage means are retained in the power-supply backup storage means and continued even when the power supply is stopped during self-diagnosis. An object of the present invention is to provide a storage content protection method that enables stable data processing.

[0006]

In order to achieve this object, a storage content protection system of the present invention comprises an arithmetic processing means for performing arithmetic and control, a power backup storage means, and a non-power backup arithmetic storage means. A first threshold level setting means for resetting the operation of the arithmetic processing means, the power supply backup storage means, and the non-power backup storage storage means, and a first threshold level setting voltage for setting the voltage of the first threshold level. Higher voltage second
And a second threshold level setting means for setting a voltage of the threshold level of, and a drop of the power supply voltage supplied below the first threshold level setting voltage occurs,
In addition, before the voltage drop of the second threshold level, the arithmetic processing means writes the stored contents of the non-power backup arithmetic storage means in the power backup storage means in any processing state.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of a storage content protection system of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of the embodiment.

In FIG. 1, reference numeral 1 denotes an arithmetic processing unit (CPU) that performs arithmetic processing at high speed, and controls the entire apparatus.
Reference numeral 2 denotes a ROM, which stores arithmetic and control programs for the arithmetic processing unit 1 to perform arithmetic and processing. Reference numeral 3 denotes a RAM for non-power backup, which is used when the arithmetic processing unit 1 performs arithmetic operations. It is a so-called working RAM,
Since it is a non-power backup, the stored contents are lost when the power supply is stopped. Reference numeral 4 denotes an S-RAM whose power is backed up, and retains the stored contents even when the power supply is stopped. 5 is S-
It is a battery that backs up the RAM 4.

Reference numeral 6 denotes a power-on / clear circuit for processing so-called power-on / clear at a threshold level V2. The threshold level V2 is a voltage higher than the operation guarantee voltage of the signal processing unit of this device and is an arithmetic processing unit. This is a voltage set to reset 1 and prevent writing of the S-RAM. Therefore, when the power supply voltage is lower than the threshold level V2, the contents stored in the RAM 3 are lost. Reference numeral 7 denotes a voltage detection circuit that detects a threshold level V1 that is higher than the set voltage of the threshold level V2.

Next, the operation of this configuration will be described.

The threshold level V1 is lower than the power supply voltage and higher than the threshold level V2.

Normally, when energization is stopped due to a power failure, a momentary power interruption, etc., first, the voltage drops to the set voltage of the threshold level V1 and further to the set voltage of the threshold level V2. In this case, the time required to fall from the threshold level V1 to the threshold level V2 is the capacity of the power supply,
Although it depends on the discharge capacity and the like, it is about several ms. This time of several mS is a sufficient operation time for the arithmetic processing unit 1 operating on the order of several nS.

FIG. 2 shows the state of the voltage drop from the threshold level V1 to the threshold level V2.

In FIG. 2, the threshold voltage V1 is reached from the normal operating voltage V due to the stoppage of energization, and the voltage further drops to the threshold level V2. Then, the voltage becomes 0 (zero) voltage V0.

In this case, the time from the threshold level V1 to the voltage drop to the threshold level V2 is a time t of several ms. Here, the set voltage of the threshold level V1 is set to the minimum fluctuation, that is, the operation guarantee voltage of the signal processing unit or more, in consideration of the fluctuation voltage V ± dv of the normal operation voltage V.

Here, if the arithmetic processing unit 1 detects the threshold level V1 during the processing of the S-RAM 4 including self-diagnosis and interrupt processing occurs, the storage contents of the non-power backup RAM 3 is backed up by the power supply during any operation. The writing process to the created S-RAM 4 is given the highest priority.

That is, the writing process to the S-RAM 4 is performed within a time t of several mS from the voltage drop from the threshold level V1 to the threshold level V2.

Therefore, even if the energization is stopped during the self-diagnosis, the contents stored in the RAM 3 for non-power backup can be held in the S-RAM 4.

There is a case where the S-RAM 4 cannot store data during the time required for the threshold level V1 to fall to the set voltage because the S-RAM 4 has a large memory content. In this case, the processing of the stored information for the RAM 3 may be divided so as to be performed during this descent time.

Further, when the processing of the stored information for the RAM 3 is not performed in the interrupt processing when the threshold level V1 is detected, the arithmetic processing unit 1 continues the processing as it is and resets at the set voltage of the threshold level V2. Then, the arithmetic processing is stopped.

[0022]

As is apparent from the above description, in the memory content protection system of the present invention, the applied voltage supplied below the set voltage of the first threshold level drops, and
Before the voltage drop of the second threshold level, the arithmetic processing means writes the stored contents of the non-power backup arithmetic storage means to the power backup storage means in any processing state, so that energization stop occurs during self-diagnosis. Also in this case, there is an effect that the storage contents of the non-power backup calculation storage means can be held in the power backup storage means to perform continuous and stable data processing.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration in an embodiment of a storage content protection system of the present invention.

FIG. 2 is a diagram for explaining the operation of the embodiment and showing a state of voltage drop from the threshold level V1 to the threshold level V2.

FIG. 3 is a sequence diagram for explaining the operation of a conventional example and showing a processing procedure for self-diagnosis.

[Explanation of symbols]

 1 arithmetic processing unit 2 ROM 3 RAM 4 S-RAM 5 battery 6 power-on / clear circuit 7 voltage detection circuit

Claims (1)

[Claims] 1. An operation of arithmetic processing means for performing arithmetic and control, power supply backup storage means, non-power supply backup arithmetic storage means, operation processing means, power supply backup storage means and non-power backup arithmetic storage means. Resets the first threshold level voltage setting first
Threshold level setting means and second threshold level setting means for setting a voltage of a second threshold level higher than the first threshold level setting voltage, and a first threshold level setting voltage. The power supply voltage stored in the non-power backup calculation storage means is stored in the non-power backup calculation storage means in any processing state before the second supply of the power supply voltage drops and the setting voltage drop of the second threshold level. A storage content protection method characterized by performing a process of writing to a means.