JP2731251B2 - Computer system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a microcomputer system, and in particular, to determine whether data held in a memory with a battery backup is normal. To a computer system that is capable of doing so.

(Related Art) In recent years, with the remarkable development of semiconductor technology, a system using a microcomputer as a control center has been widely used. In a system using a microcomputer, accurate and complicated control has become possible by performing control by software. By the way, in a system using a microcomputer, the execution program is stored in a memory and executed. In general, a ROM or a RAM is used as a memory for storing an execution program and data. Of these, when using a ROM, the ROM is non-volatile, so there is no loss of stored information, but it is not easy to change the program,
There is also a problem that the execution speed is slower than that of RAM.
On the other hand, when using RAM, the execution speed is fast, and
Because of random access, rewriting of stored contents is easy and programs and data can be easily changed. However, since it is volatile, stored information is lost when the power is turned off. Therefore, low power consumption C-MO
Using S SRAM (static RAM) etc., providing a battery as a backup power supply, and when the system power is turned off,
A memory backup system in which power is supplied from a backup power supply to an SRAM to retain stored information is also widely used.

In such a RAM of the memory backup method, information stored in the memory can be held by a backup power supply, but there is a problem of battery consumption because a battery is used as the backup power supply. That is, when the battery voltage decreases, the stored information cannot be retained at last, and the stored information in the memory is lost. If you start the microcomputer system without knowing this, it will cause runaway, and if it is used for controlling equipment, it will damage the control target or harm the surroundings It will also be.

Therefore, when the system is started, it is necessary to check whether or not the storage information to be stored in the memory when the system power is restored is normally held, or to check the storage state. A mechanical switch that forms a battery power supply path to the battery is provided, and this is used as a battery backup setting switch. If this switch is turned on, a battery backup is made. When the system starts up, the switch is turned on. The processor (CPU) reads and checks whether the system data is turned off or off to determine whether the system data in the memory has been saved. In this case, since the switch status is simply checked, if the switch is turned on, it is determined that the data is backed up. Can not do it.

(Problems to be Solved by the Invention) In a computer system such as a microcomputer or an application device thereof, in which data and programs are stored in a memory such as a RAM and used, even when a power supply is turned off or a power failure occurs. When storage of system data or the like is necessary, a battery for memory backup is provided to back up the memory in which data to be stored is stored. The power supply from the battery to the memory is provided with a mechanical switch that can be turned on to supply battery power to the memory.When the system is restarted, the CPU checks this switch to back up the memory. It was to detect whether or not it was done.

On the other hand, the RAM constituting the memory circuit retains the stored information as long as the voltage is supplied to the power supply terminal within a certain specified voltage range. However, when the voltage decreases, the stored information cannot be retained.

However, since the voltage of the battery for the battery backup cannot be checked as described above, the loss of the data in the backup memory due to the decrease in the voltage of the battery for the battery backup cannot be detected. Despite having done so, there was a concern that the system would start when it was determined that it was backed up when it was restarted. Also, if the switch is tampered with during a power failure or the like, data will be lost. And, when the computer system is started in a state where the storage information in the memory has disappeared or changed, a runaway may be caused, and when controlling a device, the control target may be damaged, There is a drawback in that it causes harm to the surroundings and lacks safety and reliability.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a computer system with a battery backup memory device capable of checking the loss of data in a backup memory due to a voltage drop of a battery for a battery backup or the like.

[Configuration of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention is configured as follows. That is, a battery backup memory device is provided, important information to be stored is held in the battery backup memory device, and the important information held in the battery backup memory device is read and used after the system power is restored. In the computer system, a battery backup setting switch for turning on / off the supply of backup power to the battery backup memory device, and a predetermined address of the battery backup memory device and a non-volatile memory stored in a non-volatile memory during the supply period of the system power. Means for storing second specific collation information identical to the stored first specific collation information; and, when the system power supply returns from a cut-off state, whether the battery backup setting switch is on or off. In a state First determining means for determining whether the battery backup memory device
And second comparing means for reading out the specific collation information and comparing it with the first specific collation information to determine whether or not the two specific collation information coincide with each other. With this configuration, the first determination unit determines that the battery backup setting switch is in the ON state, and the second determination unit matches the second specific verification information with the first specific verification information. When it is determined that the information stored in the battery backup memory device is normally held, the system is restarted, while the other determination results are obtained by the first and second determination means. In this case, it is determined that the information stored in the battery backup memory device has been lost, and a warning is issued and error processing is performed. One in which the.

(Operation) In such a configuration, the battery backup memory device stores specific information for collation at a predetermined address, and the processor of the computer system sends the collation specific information from the battery backup memory device when the power is restored. A function of reading out and collating the specific information, and determining that the storage information of the battery backup memory device is normally held when the specific information is normal and the battery backup setting switch is turned on. It has. When the power is restored, the processor reads the verification specific information from the battery backup memory device and verifies the specific information. If the specific information is normal and the battery backup setting switch is turned on, the processor determines that the specific information is normal. It is determined that the stored information is normally held, and the processing shifts to system control. As a result of the comparison, if the specific information is not normal or the battery backup setting switch is not turned on, it is determined that the information held in the battery backup memory device is lost, and a predetermined error process or the like is performed. Or enter a system control by issuing a warning.

By doing so, the backup memory holding the important data of the system becomes equal to or lower than the data storage voltage due to a drop in battery voltage, etc., and although the data to be stored is lost, it is erroneously determined to be normal. The system can be prevented from restarting, and a highly reliable computer system can be provided.

(Embodiment) FIG. 1 shows a configuration diagram of a microcomputer system using a battery backup memory according to the present invention. In the figure, 1 is a microprocessor (CPU) and 2 is a ROM (Read Only Memory). Also,
Reference numerals 3 and 4 denote first and second memory circuits constituted by a RAM, of which the second memory circuit 4 is a battery backup memory using a static RAM. 5 is a battery backup setting switch, 6 is a backup battery, 7 I / O circuit, 8 is a power supply circuit, and 9a and 9b are backflow prevention diodes.
The power supply circuit 8 supplies a drive power supply used in the system. Usually, the power supply circuit 8 transforms a commercial AC power supply into a DC to generate a necessary DC voltage. Supply DC voltage. The RO
A program to be executed by the CPU 1 is stored in M2, and the first memory circuit 3 is used as a data storage area, a working area, and the like necessary for executing the program. The second memory circuit 4 is a memory for storing system data that needs to be stored, and is backed up by a backup battery 6. Diodes 9a and 9b for backflow prevention are second
The anode side is connected to the power supply terminal of the memory circuit 4 of each of the above.
Is supplied to the second memory circuit 4, and the diode 9 b is configured to supply the supply output from the backup battery 6 to the second memory circuit 4. The battery backup setting switch 5 is connected to the backup battery 6.
Is turned on / off to supply the output of the second memory circuit 4 to the second memory circuit 4. When this output is turned on, the battery power is supplied to the backup state, and when the output is turned off, the backup is released. The I / O circuit 7 is an input / output port for reading the setting state of the battery backup setting switch 5 into the CPU 1. The CPU 1 reads the setting state information of the battery backup setting switch 5 through the I / O circuit 7. , And obtains information on whether or not the second memory circuit 4 is backed up by a battery.

In this system, important data of the system is always saved in the second memory circuit 4, so that the CPU 1 can refer to it whenever necessary. Further, the system program of the ROM 2 is configured such that initialization is performed when the power is restored, and thereafter, important data of the system saved in the second memory circuit 4 is read and initialized. It is configured to check whether or not data previously saved in the second memory circuit 4 has been lost. This check is performed based on the setting state information of the battery backup setting switch 5, but the point that this system is significantly different from the prior art is that the specific check information CD of the second memory circuit 4 is checked together with this check. The difference is that the loss of the data held in the second memory circuit 4 due to the drop in the backup battery voltage is checked.

That is, as shown in FIGS. 2 (a) and 2 (b), specific data identical to each other are stored in predetermined address areas of a read-only memory ROM2 and a second memory circuit 4 which is a read / write memory with battery backup. The configured specific backup information CD for the battery backup check is stored, and both data are read and collated at the time of restart upon power recovery. It is a point provided.

 Next, the operation of the present apparatus having such a configuration will be described.

In FIG. 1, at the time of restart, the CPU 1 reads a program from the ROM 2, accesses the memory circuits 3 and 4 as necessary, and executes a predetermined process. By setting the battery backup setting switch 5, the memory 4 is supplied with power from the backup battery 6 even when the system is not used or when a power failure occurs, thereby preventing stored data from being lost. Then, important data that should not be lost is sequentially stored in this memory, and the specific verification information CD for battery backup check is stored in the second memory circuit 4 at the time of data update or system initialization. At the predetermined address.

In this system, when the power is turned off, the power is restored, and the power is restarted, the CPU 1 first reads the setting state of the battery backup setting switch 5 by the I / O circuit 7, and determines whether the switch is in the “on” state. It is checked, and if "ON", the specific collation information CD stored in the predetermined address of the second memory circuit 4 is read and collated with the specific collation information CD stored in the ROM 2. Then, if they match, it is only at this point in time that the data held in the second memory circuit 4 is determined to be stored normally and a predetermined operation is executed. If the battery backup setting switch 5 is “OFF” or the collation result of the specific collation information CD does not match, it is determined that the data held in the second memory circuit 4 has been lost and a warning is issued. , Error processing, etc.

In the conventional system, when the power is turned off, the power is restored, and the power is restarted, the CPU 1 first reads the setting state of the battery backup setting switch 5 by the I / O circuit 7, and if the switch is in the "on" state, it should be saved. It determines that the system data is stored in the battery backup memory and executes a predetermined operation. In this case, the voltage falls below the data holding voltage of the battery backup memory due to a drop in the voltage of the backup battery or the like, and the data is held in the memory. Is not guaranteed, the backup state of the memory is determined only based on the setting state of the battery backup setting switch 5. Therefore, there is a risk of erroneous determination. Write the data to the ROM and memory for battery backup, and By checking both data by air to know whether the stored data is normal or not, if the stored data is lost, it can be surely checked if it is lost, so the system is restarted without knowing that the stored data is lost This can prevent the danger of causing a computer system to be highly reliable.

In addition, since a part of the area in the memory with battery backup is used as a method for confirming the backup of the data held in the memory with battery backup, this method hardly increases the number of components and can be implemented at low cost. Furthermore, if the battery backup setting switch is turned on and off several times when the system is turned off, including during a power failure, and the setting switch is in the "set" state at the time of restarting, save the battery. Although the storage of the data to be performed is not guaranteed, the present invention can prevent erroneous activation in such a case.

It should be noted that the present invention is not limited to the embodiment described above and shown in the drawings, and it is a matter of course that the present invention can be appropriately modified and implemented within the scope not changing the gist. Although the collation data is stored in both of the battery backup memories, the collation data may be stored in a plurality of different addresses of the battery backup memory and checked. Also, the setting state of the battery backup setting switch does not necessarily need to be checked. Further, a parity bit or the like for detecting a code error may be added to the battery backup identification data, whereby the ability to detect data loss can be further enhanced.

[Effects of the Invention] As described in detail above, the present invention transfers the collation data for battery backup check to a memory with battery backup during system operation and writes the collation data. And the ON / OFF state of the battery backup setting switch is determined, and whether or not the backup data is normally backed up by the correctness of the verification data and the ON / OFF state of the battery backup setting switch is checked. It is possible to know with high accuracy whether or not the data held in the battery-backed memory holding important data is normally held. Therefore, if data is lost due to a drop in the backup battery voltage, etc. So you can prevent malfunctions before they happen. It is possible to provide a computer system capable of performing a highly reliable restart operation.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 is a memory map showing a storage area of verification data for battery backup check in a memory used in the present apparatus. 1 microprocessor (CPU), 2 ROM (read only memory), 3, 4 memory circuit, 5 battery backup setting switch, 6 backup battery, 7 I / O circuit , 8... Power supply circuit, 9a, 9b...

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Morifumi Okukawa 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Inventor Kimitoshi Nakamura 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Japan (56) References JP-A-63-276111 (JP, A) JP-A-57-3121 (JP, A) JP-A-63-34654 (JP, A) JP-A-62-169218 (JP JP, A)

Claims (1)

(57) [Claims] A battery backup memory device;
A computer system in which important information to be stored is held in the battery backup memory device, and the important information held in the battery backup memory device is read and used after system power is restored. A battery backup setting switch for turning on / off the supply of backup power; and first specific collation information stored in a non-volatile memory at a predetermined address of a battery backup memory device during a supply period of the system power. The same as the second
Means for storing the specific collation information, and first determining means for determining whether the battery backup setting switch is in an on state or an off state when the system power supply returns from a cut-off state, A second determination unit that reads the second specific collation information from the battery backup memory device, collates the second specific collation information with the first specific collation information, and determines whether both the specific collation information match; When the first determination means determines that the battery backup setting switch is turned on, and when the second determination means determines that the second specific collation information matches the first specific collation information. Then, it is determined that the information stored in the battery backup memory device is normally held, and the system is restarted. Means for performing a warning and performing an error process by determining that the storage information of the battery backup memory device is lost when another determination result is obtained by the determination means. Computer system.