JPH01180688A - Portable electronic device - Google Patents

Abstract

PURPOSE:To prevent a writing error out of the rewritable number of times by providing a counter means to count writing actions and a storage means to store information about the rewritable number of times. CONSTITUTION:In the specific area of a non-volatile memory 12, a storage means 124 to store the information about the rewritable number of times held by a non-volatile memory is provided, a counter means 125 to count the number of times each time the writing action is executed to the non-volatile memory 12 is provided, when the writing action is requested of the non-volatile 12, the value of the counter means 125 is compared with a value in the storage means 124 and by this comparison result, the writing action to the non-volatile memory 12 is controlled. Thus, the writing actions to the non-volatile memory 12 are restrained within the rewritable number of times and the writing error can be prevented.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention provides an IC (integrated circuit) chip having a built-in IC (integrated circuit) chip having a control element such as a rewritable and erasable non-volatile memory and a CPU, for example. The present invention relates to a portable electronic device called an IC card.

(Prior Art) Recently, an IC card containing a built-in IC chip having a nonvolatile memory and a control element such as a CPU has been developed as a new portable data storage medium. This kind of I
The C card accesses a built-in nonvolatile memory using a built-in control element, and inputs and outputs necessary data in response to requests from external devices.

Now, most of the nonvolatile memories used in such IC cards are EEFROMs, which are also rewritable. EEPROM is rewritable and erasable, but when accessing stored data, the reliability of stored data is high by adding/checking redundant data for checking data validity, and before accessing stored data, Only legitimate access is allowed by checking the legitimacy of the requester and the presence or absence of access rights.

As described above, the IC card has high reliability in terms of the authenticity of the access requester and the storage state of stored data, but problems are concentrated during data rewriting or erasing operations, for example.

That is, when executing a write-related operation (including not only a write operation but also an erase operation), in order to improve memory efficiency, even if a - degree of write error occurs, rewriting is executed to the same area. Furthermore, the rewrite operation is performed as many times as requested without considering the number of times that the same area of the memory can be rewritten. However, EEFROM usually has a rewritable number of times guaranteed by the manufacturer (limited number of times of writing to the same area), and by repeating the above operation, EEPROM
The number of rewrites that can be exceeded may be exceeded. Then, when the stored data is read out, processed, and stored in the same area again, a write error occurs, and there is a risk that both the original data and the newly written data will be destroyed.

(Problems to be Solved by the Invention) As described above, the present invention is to address the problem that the write operation to a non-volatile memory may exceed the number of times that the non-volatile memory can be rewritten, and as a result, a write error occurs and the data is This was developed to solve the problem of the risk of destroying data, and it prevents write errors outside the number of times that nonvolatile memory can be rewritten, making it portable without the risk of destroying data. The purpose is to provide electronic devices.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a rewritable and erasable nonvolatile memory;
The nonvolatile memory has a control unit for reading and writing data to and from the nonvolatile memory, selectively inputting and outputting data from the outside, and the nonvolatile memory has a data area for storing data, and a data area for storing data. and an area definition information area for storing area definition information defining the data area, the portable electronic device comprising: an area definition information area for storing area definition information defining the data area; a counter means for counting the number of times, and a counter means provided in the area definition information area,
storage means for storing information on the number of times the nonvolatile memory can be rewritten; and comparison means for comparing the value of the counter means and the value in the storage means when a write operation request is made to the data area. and a control means for controlling a write operation to the data area based on the comparison result of the comparison means.

(Function) In a specific area of the nonvolatile memory, a storage means is provided that stores information on the number of times the nonvolatile memory can be rewritten, and each time a write operation is performed on the nonvolatile memory, the number of times the write operation is performed is recorded. A counter means for counting is provided, and when a write operation request is made to the nonvolatile memory, the value of the counter means is compared with the value in the storage means, and the write operation to the nonvolatile memory is performed based on the comparison result. It is something to control. Thereby, the write operation to the nonvolatile memory can be suppressed to within the number of rewrites that the nonvolatile memory has, and it is possible to prevent write errors outside the number of rewrites that the nonvolatile memory can have.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 3 schematically shows the configuration of an IC card as a portable electronic device according to the present invention, which includes a control element (for example, a CPU) 11 as a control section, a data memory 12, a program memory 13, and a It is composed of a contact section 14 for electrically communicating with a terminal device, etc., of which the part within the broken line (the control element 11,
data memory 12, program memory 13) is one I
It is composed of a C chip (or multiple IC chips).
It is buried within the C card body. Program memory 1
Reference numeral 3 is composed of, for example, a mask ROM, and stores a control program for the control element 11 and the like. The data memory 12 is used to store various data, and is composed of a rewritable and erasable nonvolatile memory such as an EEFROM.

The data memory 12 is largely divided into an area definition information area 121 and a data area 122, as shown in FIG. 1, for example. The area definition information area 121 stores a plurality of area definition information 123 that defines the data area 122 as being divided into a plurality of areas. The area definition information 123 that defines the division of one area includes an area number that defines a unique number for the area, a start address that defines the position of the area in the data area 122, an area size that defines the size of the area, and the state of the area. information(
(information indicating the number of stored data, whether the area can be used, etc.).

With such a configuration, when there is an external data write request, the control element 11 writes the area definition information area 12.
By referring to area definition information having information that defines a designated area within 1, the state of the designated area is recognized and a data write operation is performed. When data is written in a designated area, information for checking data validity is added to the data, and the record including the data is called a record (the shaded area in FIG. 1) and is treated as a unit of stored data. Please note that only one record exists in one area,
When there is a data write request, existing data may be overwritten. Additionally, adding data to an area means adding a new record, or rewriting data in an existing record if a record is specified.

Further, the area definition information area 121 is provided with a rewriteable number information storage area 124 and a data rewrite number counter area 125 corresponding to each area definition information 123, respectively.

The rewritable number information storage area 124 stores in advance the rewritable number information for the same location guaranteed in the data memory 12. The data rewrite count counter area 125 has the corresponding area definition information 123
There is a write operation request for the area defined by , and if the write operation is actually performed, the count increases. Counting operation control for this data rewriting number counter area 125 is performed by the control element 11.

When a data write operation request is made to an IC card that has area definition information that includes these two types of information (number of rewrites and number of data rewrites), the write operation is performed according to the flowchart shown in Figure 2. .

That is, if a write operation request to a certain area is confirmed, the control element 11 writes the rewritable number information storage area 124 corresponding to the area definition information 123 of the specified area.
The information on the possible number of rewrites in the data is compared with the count value of the corresponding data rewrite number counter area 125 to check whether the two are equal. As a result of this check, if the two are equal, it means that future writing to the area will exceed the limit of the number of rewrites guaranteed by the manufacturer of the data memory (EEPROM) 12, and therefore the control element 11 stops writing data to that area. This makes it possible to prevent write errors that have a high probability of occurring.

As a result of the above check, if the two are not equal, that is, if the count value in the data rewrite number counter area 125 is smaller than the rewrite number information in the rewrite number information storage area 124, the limit of the number of rewrites has not yet been exceeded. Therefore, the control element 11 writes data to that area. When the data write is completed, the control element 11 counts up the value in the data rewrite counter area 125, and thereafter completes the write operation through the process shown in the flowchart of FIG. 2.

In this way, within the area definition information area 121 of the data memory 12, there is a rewritable number information storage area 124 that stores the rewritable number information of the data memory 12 corresponding to each area definition information 123, and A data rewriting frequency counter area 125 is provided that counts up the number of times a write operation is performed on the area defined by the area definition information 123, and when a write operation request is made to the data memory 12, The value in 124 is compared with the value in the counter area 125, and if as a result of this comparison, both are equal, the write operation to the area defined by the area definition information 123 having that counter area 125 is not performed. It is something to control. As a result, the write operation to the data memory 12 can be suppressed within the number of rewrites that the data memory 12 has, and a write error outside the number of rewrites that the data memory 12 can have can be prevented. There is no risk of destroying it. Furthermore, since this is automatically done within the IC card, the terminal device that handles the IC card is not aware of it.

In the above embodiment, the case where the processing is performed in units of areas has been described, but the processing may be performed in units of records. In that case, a data rewrite count counter area should be provided for each record, and when that record is specified for a write operation, the data should be compared with the rewrite limit information in the area definition information area and the counter area should be counted up. Accordingly, the same effects as in the above embodiment can be obtained.

[Effects of the Invention] As detailed above, the present invention provides a portable electronic device that prevents write errors outside the number of times that a nonvolatile memory can be rewritten and that does not pose the risk of destroying data. can.

[Brief explanation of the drawing]

The figures are for explaining one embodiment of the present invention, and FIG. 1 is a configuration diagram of a data memory, FIG. 2 is a flowchart explaining a data writing operation, and FIG. 3 is a schematic diagram of the configuration of an IC card. FIG. 11... Control element (control unit, comparison means, control means),
12...Data memory (non-volatile memory), 13...
・Program memory, 121... Area definition information area, 122... Data area, 123... Area definition information, 124... Rewritable number of times information storage area (
storage means), 125... data rewriting number counter area (counter means). Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2 (a) Figure 3

Claims (1)

[Claims] A rewritable and erasable nonvolatile memory, a control unit for reading and writing data to the nonvolatile memory, selectively inputting and outputting data from the outside, and The non-volatile memory is a portable electronic device that is divided into a data area for storing data and an area definition information area for storing area definition information defining this data area; a counter means provided in the area definition information area for counting the number of times a write operation is performed on the data area; and a counter means provided in the area definition information area for storing information on the number of times the nonvolatile memory can be rewritten. storage means; comparison means for comparing the value of the counter means and the value in the storage means when a write operation request is made to the data area; a write operation to the data area is performed based on the comparison result of the comparison means; A portable electronic device characterized by comprising: a control means for controlling the