JPH01107400A - Setting method for switch system by eeprom - Google Patents

Abstract

PURPOSE:To substantially decrease the number of time of write of a cell and to raise its reliability by constructing a switch system for installing a data in an information apparatus by using a cell array. CONSTITUTION:The number of cells of an array is made larger than the number of data storage cells, the number of addresses is shifted at every rewriting, and a data overflowed from the array executes such cyclic write as writing from a head address of the array. Accordingly, comparing with the case when write is executed by making the number of cells of the array the same as the number of data storage cells, the number of times of write decreases substantially, as for each cell. Also, as for the cell in which an error is generated, it is disposed of so that its address can be known by a managing means, by which thereafter, the cell concerned can be removed at the time of rewriting. Also, in which cell a data is stored can be known easily by detecting an address of a tag. In such a way, a switch having reliability which is settled a problem of reliability by limiting the number of rewriting of an EEPROM can be constructed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a switch system that uses data stored in an EEPROM as a series of switch data. In particular, the present invention relates to a system in which switch data can be rewritten and reset using the characteristics of EEPROM (electrically erasable programmable ROM).

[Conventional technology]

In information equipment, in order to set certain data,
A mechanical dip switch is often used. However, recently, EEPROMs, which are electrically erasable and can be written many times, are often used in place of conventional dip switches. Dates inch is 1”.

Although it can only store two values, ``0'', in EEPROM it is easy to set multiple bits to one address, and more complex data can be stored, so the range of application as a system is widened.

[Problem that the invention seeks to solve]

Conventionally, switch systems using this type of EEPROM have used fixed EEPROM addresses. For example, as shown in FIG. 4, even if an EEPROM has eight cells with addresses O to 7, (
When rewriting cells in which data A, B, and C have been written as shown in a), data A' and B' are written to cells at the same location as shown in (b).
, C' and rewrite the data. Therefore, EEPROM
When a certain byte or bit reaches the limit of the number of times it can be rewritten,
There was a drawback that the entire system was invalidated. Further, the write check merely compares write data and read data to check for errors, and no particular measures have been taken to avoid errors.

SUMMARY OF THE INVENTION An object of the present invention is to provide a setting method for constructing a reliable switch system that solves the reliability problem caused by the limit on the number of times EEPROM can be rewritten.

[Means for solving problems]

The method for rewriting a switch system using an EEPROM of the present invention is to predetermine the number of cells in the array to be larger than the number of cells in which data is to be stored, store a specific tag at the beginning in the cell array, and write the tag to the address of the tag. means for storing a series of data in cells at subsequent addresses, excluding cells at addresses determined to be defective by a management means described later;

Each time data is rewritten, the address of a series of data is shifted for each tag, and data that overflows from the array is written from the first address at the beginning of the array.A cyclic rewrite means is used, and cells that are found to be defective in the post-rewrite check are Skip the cell and write to the next cell, and
This includes means for managing the data so that it is not used for subsequent rewriting.

[Effect]

The number of cells in the array is made larger than the number of data storage cells, the number of addresses is shifted every time data is rewritten, and data overflowing from the array is written in a cyclic manner such that it is written from the first address at the beginning of the array. Therefore, compared to the case where the number of cells in the array and the number of data storage cells are the same and rewriting is performed, the number of times each cell is written is substantially reduced.

Furthermore, if the address of a cell in which an error has occurred is made known by the management means, the cell can be removed at the time of subsequent rewriting. You can easily find out from which cell the data is stored by detecting the address of the tag.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an example of the rewriting method of the present invention. (a) shows the storage status of an EEPROM at a certain time, with a tag at address O and subsequent addresses 1 and 2.
．． Data A, B, and C are stored at each address of 3.

Note that address 7 is a cell that has been previously determined to be defective by error checking, and for management purposes, a tag indicating that it is a defective address is fixedly attached (registered) to the cell.

Rewriting is done by shifting the address as shown in Figure 1(b).
Write rewrite data ', B', and C'.

At this time, if there is data at address 6, there is a defective address tag at address 7, so new data is cyclically written to address 0 during rewriting. In this way, the cell storing data moves, but since there is a tag at the beginning of the cell, the address where the data is located can be easily known, and the defective address tag allows writing to be performed by skipping that cell.

Next, the error checking operation will be explained with reference to the flowchart shown in FIG. This flowchart relates to writing one piece of data. First, data is written (Pl) to a predetermined address. Then read it out (P2
) and compare it with the written data (P3). If the data is lost once, the writing ends, but if the written data and the read data are different, rewriting is performed. Set a limit on the number of rewrites so that the number of rewrites is within the limit (P
4), further rewriting and error checking are performed (Pi to P3). If the number of rewrites exceeds the limit, the cell at that address registers that address as a defective cell (P5), returns to Pi, and writes data to the next address after this address. However, this jump can only be performed when the number of data is less than the writable area (P6), which is the total number of address cells minus the number of defective address cells. Otherwise, data can no longer be written. It is judged as an error (
P7).

Defective addresses can be managed by attaching a defective address tag to a specific address in the cell array as described above, but as an alternative method, for example, the management file 2 shown in FIG. 3 can be stored in another area of the EEPROM. It is also possible to refer to this file by registering a good cell as "1" and a defective cell as "0" in accordance with the address of the cell array 1 of the EEPROM of the switch system.

〔Effect of the invention〕

As explained above, the present invention relates to a method of constructing a switch system for installing data in information equipment using a cell array in an EEPROM.
By making the number of cells in the array larger than the number of data and cyclically writing by shifting the address for each rewrite, it is possible to substantially reduce the number of times cells are written and improve their reliability.゛If there is a defective cell, this cell is skipped and the data is written to the next address, so even if a defective cell occurs, the switch system can still function as long as there is a margin equal to the number of cells in the array minus the number of data. This has the advantage of extending the service life of the system.

[Brief explanation of the drawing]

Figures 1 to 3 relate to an embodiment of the present invention, with Figure 1 being a diagram showing the concept of this method, Figure 2 being a flowchart for checking for defective data settings in this system, and Figure 3 being a diagram showing defective cells. FIG. 4 is an explanatory diagram showing an example of a management method, and FIG. 4 is a diagram showing the concept of a conventional example. 1-Cell array, 2-Management file.

Claims (1)

[Claims] In a switch system constituted by a cell array in which a plurality of series of data are stored in an EEPROM, the number of cells in the array is determined in advance to be larger than the number of cells in which data is to be stored, and the number of cells in the cell array is means for storing a specific tag at the beginning, and storing a series of data in cells at addresses following the address of the tag, excluding cells at addresses that are determined to be defective by the management means described later;
Each time data is rewritten, the address of a series of data is shifted for each tag, and data that overflows from the array is written from the first address at the beginning of the array.A cyclic rewrite means is used, and cells that are found to be defective in the post-rewrite check are Skip the cell and write to the next cell, and
1. A method for setting a switch system using an EEPROM, comprising means for managing the EEPROM so that it is not used for subsequent rewriting.