JP3012737B2 - Method of writing data to E2ROM - Google Patents

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 an improvement in a method of writing backup data to backup data.

[0002]

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

[0003]

However, unlike a normal RAM that is backed up by a battery, the maximum number of write operations that can be guaranteed in the E ² ROM is determined in advance from the hardware characteristics. Therefore, there has been a problem that if data is written more than the determined maximum number of times, the written data cannot be guaranteed.

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
To provide a method of writing data to the memory.

[0005]

According to the present invention, an E ² ROM in which backup data of an apparatus provided with a control system including a CPU is written is stored in the E ² ROM at a predetermined maximum number of times of writing to the E ² ROM. previously guaranteed is to partition the maximum backup data write count the number of blocks of more than a value obtained by dividing the write times for each block
Count the number of blocks and write the
And performing write Te.

[0006]

[0007]

According to the present invention, the E ² ROM is divided into blocks equal to or larger than a value obtained by dividing the maximum number of times of backup data writing guaranteed in advance by the maximum number of times of writing predetermined in the E ² ROM. For example, if the predetermined maximum number of times of writing to the E ² ROM is 100,000 and the maximum number of times of backup data guaranteed to the device is 1,000,000, a value obtained by dividing 1,000,000 times by 100,000 times. The E ² ROM is divided into 10 blocks or more. Furthermore, in each block
The number of times of writing is counted. Write data to E ² ROM
The number of writes in each block,
Write to the block with the least number of writes
Done. As described above, when the E ² ROM is divided into blocks, a predetermined maximum number of times of writing for one entire E ² ROM can be guaranteed for each block. The number obtained by multiplying the number of times of writing by the number of blocks can be guaranteed as the maximum number of times of writing backup data of the device. Also, for the block with the least number of writes
Read point bit by writing
Focus on a single block when errors occur
Of data reliability due to data being written to
Can be prevented.

[0008]

FIG. 1 is a block diagram of a typical control unit 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 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 RAM 5
It is necessary to save the data stored on the E ² ROM 6 as backup data.
Transfer to The E ² ROM 6 receives the data stored in the RAM 5 from the CPU 1 and stores it in a short time from when the power is turned off to when a complete power failure occurs. E ² ROM
Since the battery 6 does not need to be backed up by a battery, when the power is turned on again, data is read from the CPU 1 by the initial routine and stored in the RAM 5 again. When such a control system is applied to, for example, a copying machine, various process data such as an accumulated number of copies, a charging voltage, a developing bias voltage, and a static elimination 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 determined by the maximum number of backup data
⁽²⁾ The size is equal to or larger than a value obtained by dividing by a predetermined maximum number of times of writing to the ROM 6.

For example, the maximum number of backup data write operations guaranteed in the device in advance is 400,000, and the E ² RO
Assuming that the maximum number of times of writing predetermined for 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 four blocks. Each of the blocks 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 has been performed on each block.

FIG. 3 shows a flowchart when writing backup data to the E ² ROM shown in FIG. This usually happens when the device is turned off,
Executed when there is a momentary power failure.

First, a counter x for counting a block number is set to 1, and a write counter WC of a block designated by the x is read. Let the value be Y.
Judge whether the value of Y exceeds 100,000 times,
If not, the backup data is written to the current block, the write counter WC of the block is counted up, and the process ends. On the other hand, if the count value Y of the write counter WC exceeds 100,000 times, x is increased by 1, that is, the number of the block to be accessed is increased by 1, and the same operation as described above is performed. When writing beyond block 4, error processing is performed.

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

FIG. 4 shows another embodiment of the present invention.

In this embodiment, the access block is sequentially switched every time backup data is written.
That is, first, the write counter W of each of the blocks 1 to 4
The data Y of C (Y1 to Y4) is read. Then, the values Y1 to Y4 are compared, and backup data is written to a block having a small count value. Then, the count value of the write counter of the block is incremented by one, and the process ends. When the write counter values of all blocks are the same, block 1 is accessed and the same operation is performed. By the above operation, every time data is written, the blocks of the E ² ROM are sequentially switched. Note that even in this case,
Up to 400,000 writes can be performed.

[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 You are no longer limited by ROM. Ma
Write to the block with the least number of writes
The read error of the point bit.
Etc., even when a single block is concentrated
No data is written and data reliability is reduced
Can be reliably prevented.

[Brief description of the drawings]

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

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

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

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

Claims (1)

(57) [Claims] 1. An E ² ROM in which backup data of an apparatus provided with a control system including a CPU is written.
It is divided into the maximum number of backups data write count by dividing the value or more blocks in advance is guaranteed to the device at the maximum number of writes predetermined for the E ² ROM, each blanking
Count the number of writes to the lock, and
A method for writing data to an E ² ROM, wherein writing is performed on the least number of blocks .