JPS59188896A - Back-up system of memory information - Google Patents

Abstract

PURPOSE:To exclude a detecting circuit for power supply break etc. and to miniaturize a device by holding information assuredly just by providing plural back-up memories. CONSTITUTION:When a back-up memory flag FB is set, the flag FB is reset (process 21) to be prepared for a case where a next interruption signal is produced. Then the output time point data of a timepiece circuit 10 is read (process 22), and a flag F1 is reset (process 23). The time point data is stored (process 24) to a prescribed area of a back-up memory BM1, and the flag F1 is set (process 25). While the similar processes 26-30 are carried out with a back-up memory BM2 if the flag FB is reset. Therefore the flag F1 or F2 is reset while this timer processing PT is performed. Thus a CPU7 is stopped while the F1 of the BM1 or the F2 of the BM2 is kept reset if power failure etc. are generated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a backup method for protecting main memory information from power outages and the like in a control device using a microcomputer.

[Prior Art] Generally, in facsimile machines whose operations are controlled using a microcomputer, main data such as frequently used telephone numbers of destinations is stored in a so-called backup memory backed up by a battery. The system protects key data in the event of a power outage or momentary power outage (hereinafter referred to as power outage, etc.).

However, if a power outage occurs while data is being read or written to the backup memory described above, noise will occur on the write/read signal line due to the power outage, and as a result, the backup memory This causes the inconvenience that the memory contents change.

Conventionally, in order to solve this problem, a power failure detection circuit was provided on the AC power input side of the DC power supply circuit, and a power failure detection circuit was installed on the DC power output side to maintain the power supply voltage for a predetermined period of time immediately after a power outage, etc. occurred. When a large-capacity capacitor is connected and the power failure detection circuit detects a power outage, etc., it saves predetermined data to the backup memory, and
After that, this backup memory was prevented from being accessed to protect the contents of the backup memory.

However, such a conventional method requires a power-off detection circuit and a large-capacity capacitor, and the problem is that the fruiting device is large and expensive.

[Objective] It is an object of the present invention to provide a memory information backup method that solves the above-mentioned problems and can realize a compact and inexpensive backup device.

[Configuration] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a facsimile machine F according to an embodiment of the present invention.
It shows AX. This facsimile machine FAX holds main data such as telephone numbers using two backup memories BMI and 8M2 supplied with power from battery BT.

In the figure, 1 is a scanner that plane-scans a transmitted document and photoelectrically converts it to form a transmitted image signal, 2 is a printer that prints a dot pattern corresponding to a recorded image, and 3 is an 8-bit scanner that converts the output signal of scanner 1 into an 8-bit image signal. This is a buffer that converts the output of the code compression/decompression circuit (OCR) 4 into a serial signal and outputs it to the printer 2 while converting it into a parallel signal.The code compression/decompression circuit 4 encodes the data added from the buffer 3 and compresses the data. At the same time, the received data added from the modem 5 is decoded, data is expanded, and the data is output to the buffer 3.

6 is a network control device (NCLI) that has an automatic dialing function and an automatic reception function and controls a transmission line network such as a telephone line network to establish and disconnect a transmission line; 7 is the above-described scanner 1.
Printer 2. Buffer 3. Code compression/decompression circuit 4. A CPU (central processing unit) that controls the modem 5 and network control device 6 respectively, 8 a ROM (read-only memory) that stores programs executed by the CPU 7, and 9 a CPU
RAM that forms the work area of L17 (Random access memo January, 10 is the clock circuit, and SB is each of the above elements 1 to 10. Backup memory BMI, 8M
This is a system bus that connects 2.

With the above configuration, the CPU 7 performs the timer processing P shown in FIG.
The power restoration process PR shown in T and FIG. 3 is performed to back up information. Note that the backup memory flag FB is used to determine which of the backup memory BMI and 8M2 to select, and the flag F
1 and F2 are used to determine whether the backup memory BMI or 8M2 was accessed when a power outage or the like occurred.

The CPU 7 controls each element of the facsimile machine FAX, and executes timer processing PT when an interrupt signal output every second from a timer (not shown) is added.

In this timer processing PT, the state of the backup memory flag FB is first checked in judgment 20, and if this flag FB is set, processing is performed to reset the backup memory flag FB in preparation for the next occurrence of an interrupt signal. 21) After reading the output time data of the clock circuit 10 (process 22) and resetting the flag F1 (process 23), the time data is stored in a predetermined area of the backup memory BMI. Process 24) sets the flag F1. (Process 25).

Furthermore, if the backup memory flag FB is reset, the processes 26 to 26 related to the backup memory BM2
Execute 30. Note that these processes 26 to 30 are a series of processes 21 to 25 related to the backup memory BM1 described above.
Since it is the same as , the explanation will be omitted.

Therefore, when this timer processing PT is executed, the flag F1 or flag F2 is reset, so if a power outage etc. occurs at this time, the flag F1 of the backup memory BMI or the flag F2 of the backup memory BM is reset.
The CPU 7 will stop with the flag F2 of No. 2 in the reset state.

Therefore, in the power restoration process PR performed by the CPU 7 immediately after the power is restored, the flag F is determined by the judgment 312.
Check which of the flags F1 and F2 is in the reset state, and if the flag F1 is in the reset state, the backup memory BM
Since a power outage, etc. has occurred when I was accessed, the data in the backup memory 8M2 other than the time data is copied to the backup memory BMI and the stored contents of the backup memory BMI are corrected. 33), flag F1
(process 34), causes the printer 2 to output a display corresponding to the time data stored in the backup memory BMI (process 35), and notifies the operator of the time of occurrence of a power outage, etc.

Furthermore, if the flag F2 has been reset, processes 36 to 38 related to the backup memory BM2 are executed in the same way as the processes 33 to 35 described above, and furthermore, the flag Fl,
If both F2 are set, processing 38 is executed to notify the operator of the time when a power outage or the like occurred.

The reason why the above-mentioned interrupt signal cycle is set to 1 second is that 1. In the case of a normal power outage, the power supply voltage will stabilize in a completely decreased state in 1 second, so it can be used as a backup when the power supply voltage is unstable. This is to prevent memory BMI and memory 8M2 from being accessed together.

By the way, the CPU 7 mentioned above is a backup memory BM.
When storing data such as telephone numbers in the I, 8M2, errors and fluctuations in the data are prevented by adding error detection codes such as CRC codes (cyclic redundancy check codes), checksums, and parity bits to these data. This ensures reliable detection.

In the above description, an embodiment in which the present invention is applied to a facsimile machine FAX has been described, but the present invention is not limited to this and can be applied to other devices.

Further, although the above-mentioned embodiment is a case in which two backup memories are provided, the number is not limited to this, and the present invention can be implemented in the same manner even in the case of three or more.

[Effects] As explained above, according to the present invention, information can be reliably retained simply by providing a plurality of bank-up memories.Therefore, since there is no special need for a power-off detection circuit, etc., the device can be made smaller. It has the advantage of being highly flexible and inexpensive.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a facsimile apparatus according to an embodiment of the present invention, FIG. 2 is a flowchart showing two timer processes, and FIG. 3 is a flowchart showing power restoration processing PR. 7... CPU (central processing unit), 8... ROM (
Read-only memory), 9 RAM (random access memo January, B old, 8M2 ・Back amplifier memory, BT... battery.

Claims (1)

[Claims] (1) Storing the same information in multiple backup memories,
A method for backing up memory information characterized by sequentially changing the backup memory to be accessed from among a plurality of backup memories at predetermined time intervals when reading and writing information stored in the backup memory. (2. In claim 1, the memory information is characterized in that the predetermined time is set to be longer than at least the transient time from when a power outage occurs until the power supply voltage falls below a predetermined value. Backup method.