JPH0619800A - Method for data writing e2rom - Google Patents

Abstract

PURPOSE:To easily increse the writing frequency of maximum backup data by sorting E<2> ROM to plural blocks and writing into another block when the frequency of writing times exceeds the maximum writing frequency. CONSTITUTION:E<2>ROM is sorted to the number blocks equal or larger than a value obtained by dividing the maximum backup data writing frequency which is previously guaranteed for a device by the maximum writing frequency which is previously determined for E<2>ROM. If the maximum backup data writing frequency is four hundred thousand times and the maximum writing frequency is one hundred times, for example, the number of blocks to divide >= four. In the case of dividing E<2>ROM of KB to four blocks, the respective blocks A to D respectively have the capacity of 2KB and a write counters WC counting the number of writing times are assigned to the respective blocks. When it exceeds the maximum writing times number for one block, the writing and after it are moved to another block.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention is a device system is provided that includes a CPU, and the device using the E ² ROM to write backup data occurring power-off or the like, to the E ² ROM The present invention relates to improvement of a writing method to backup data.

[0002]

2. Description of the Related Art In a conventional device of this type, when backup data is generated, the backup data is simply written to an E ² ROM as it is.

[0003]

However, unlike the normal RAM that is backed up by a battery, the maximum write count that can be guaranteed in the E ² ROM is determined in advance because of the hardware characteristics. Therefore, there is a problem that the written data cannot be guaranteed when writing is performed more than the determined maximum number of writings.

An object of the present invention, E by devising a ² ROM, device guaranteed E ² can easily increase by the number of times of writing up the backup data is ROM
It is to provide a method of writing data to.

[0005]

According to the present invention, there is provided an E ² ROM in which backup data of a device provided with a control system including a CPU is written, in the E ² ROM at a predetermined maximum number of writes. The number of blocks is equal to or greater than the maximum backup data write count guaranteed in advance, and when the number of writes to one block exceeds the maximum number of writes, writing to other blocks is performed. It is characterized by

Further, it is characterized in that the block to be accessed is sequentially switched every time the backup data is written.

[0007]

According to the present invention, the E ² ROM is divided into a number of blocks which is equal to or more than a value obtained by dividing the maximum number of times of writing backup data which is guaranteed in advance by the device by the maximum number of times of writing which is predetermined in the E ² ROM. For example, assuming that the maximum number of times of writing in the E ² ROM is 100,000 times and the maximum number of times of writing backup data that is guaranteed in the apparatus is 1 million times, the value obtained by dividing 1 million times by 100,000 times is 10 E ^{2 to the} number of blocks or more
Divide the ROM. When the number of times of writing to one block exceeds the maximum number of times of writing (100,000 times), the subsequent writing is moved to another block. In this case, the block that has already exceeded the maximum write count is never written again. In addition, E ² ROM
When the block is divided into blocks, the predetermined maximum number of writes for one entire E ² ROM can be guaranteed for each block. Therefore, the number of blocks is set to the predetermined maximum number of writes. The number of times of multiplication can be guaranteed as the maximum number of times of writing backup data of the device.

[0008]

DETAILED DESCRIPTION FIG. 1 shows a block diagram of a typical controller including a CPU. The CPU 1 receives input data from the sensor 2, processes the input data according to a program stored in the ROM 3, and outputs the drive data to the drive unit 4. The RAM 5 is used for temporary storage and processing of data. When the power is turned off, the RAM5
It is necessary to save the data stored above, but the saved data is used as backup data in the E ² ROM6.
Transfer to. The E ² ROM 6 receives the data stored in the RAM 5 from the CPU 1 and stores the data in a short time until the power is turned off and a complete power failure occurs. E ² ROM
Since the battery 6 does not need battery backup, when the power is turned on again, data is read from the CPU 1 by the initial routine and stored again in the RAM 5. When such a control system is applied to, for example, a copying machine, various process data such as cumulative number of copies, charging voltage, developing bias voltage, discharging voltage can be considered as backup data.

In the present invention, the E ² ROM is divided into a plurality of blocks. The number of blocks to be divided is the maximum backup data write count guaranteed in advance by the device,
² The size is equal to or greater than the value divided by the maximum number of times of writing in the ROM 6 in advance.

For example, the maximum backup data write count guaranteed in advance to the device is 400,000, and E ² RO
If the maximum number of times of writing in M6 is 100,000, the number of blocks to be divided is four or more. FIG. 2 shows a case where an 8 KB E ² ROM is divided into 4 blocks. Each block A to D has a capacity of 2 KB, and a write counter WC is assigned to each block. The write counter WC counts the number of times writing is performed on each block.

FIG. 3 is a flow chart when writing backup data to the E ² ROM shown in FIG. This operation is usually done when the device is powered off,
It is executed during an instantaneous power failure.

First, 1 is set to the counter x for counting the block number, and the write counter WC of the block designated by the x is read. Let that value be Y.
Judge whether the value of Y exceeds 100,000 times,
If it does not exceed, the backup data is written to the current block, and the write counter WC of the same block is counted up to finish. On the other hand, if the count value Y of the write counter WC exceeds 100,000 times, x is incremented by 1, that is, the number of the block to be accessed is incremented by 1, and the same operation as above is performed. When attempting to write over block 4, error processing is performed.

By such an operation, writing can be performed up to 400,000 times.

FIG. 4 shows another embodiment of the present invention.

In this embodiment, the access block is sequentially switched every time the backup data is written.
That is, first, the write counter W of each block 1 to 4 is
The data Y of C (Y1 to Y4) is read. Then, the respective values Y1 to Y4 are compared, and the backup data is written to the block having the smaller count value. Then, the write counter of the block is incremented by 1 and the process is terminated. When the write counter values of all blocks are the same, block 1 is accessed and the same operation is performed. With the above operation, the blocks of the E ² ROM are sequentially switched every time data is written. Even in this case,
You can write up to 400,000 times.

[0016]

In the present invention, the writable number of times the E ² ROM, in order to be easy on the number of times previously the E greatly exceeds the maximum number of writes that are determined to ² ROM, the maximum backup data write count of the device Can be significantly increased. Therefore, the service life of the device is E
^{2 No} longer limited by ROM.

[Brief description of drawings]

FIG. 1 shows a block diagram of a CPU control system in which a data writing method according to the present invention is implemented.

FIG. 2 is a diagram showing a state when an E ² ROM is divided into 4 blocks.

FIG. 3 is a diagram showing a flowchart when writing backup data to an E ² ROM.

FIG. 4 is a flowchart showing another operation example when writing backup data to an E ² ROM.

Claims (2)

[Claims] 1. An E ² ROM in which backup data of a device provided with a control system including a CPU is written,
The E ² ROM is divided into a number of blocks equal to or larger than a value obtained by dividing the maximum number of times of writing backup data guaranteed in advance by the maximum number of times of writing to the E ² ROM, and the number of times of writing to one block is the maximum. A method of writing data to an E ² ROM, characterized in that writing is performed to another block when the number of times of writing is exceeded. ^2. An E ² ROM in which backup data of a device provided with a control system including a CPU is written,
The E ² ROM is divided into a number of blocks equal to or more than a value obtained by dividing the maximum backup data write count guaranteed in advance by the device by a predetermined maximum write count, and the blocks to be accessed are sequentially accessed for each backup data write. A method of writing data to an E ² ROM, which is characterized by switching.