JP2000339232A - Method for writing count value into nonvolatile memory - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the method for exactly storing a count value even when power interruption is caused in the case of using a nonvolatile memory as a counter. SOLUTION: Count values are circulatively and successively written in plural areas (a), (b), (c) of a count part 4 of the nonvolatile memory and the maximum value among the values written in the areas (a), (b), (c) is defined as the count value. The abnormality of the counter is detected by detecting a fact that correlation between the count values in the areas (a), (b), (c) is disordered and when the abnormality of the counter is detected, a restoration processing is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for writing a count value into a nonvolatile memory.

[0002]

2. Description of the Related Art Conventionally, in order to manage the number of prints and the life of a print drum in an electrophotographic printer, an EEP-
A counter is provided on a non-volatile memory such as a ROM, and the count value is updated when a count-up condition occurs. The printer determines the number of prints and the life of the print drum based on the count value.

[0003]

However, EEP-
A non-volatile memory such as a ROM requires 1000 times or more to write data as compared with other storage elements such as a dynamic ram (DRAM) and a static ram (SRAM) due to the nature of the element. If the power supply is suddenly cut off in the device in which the memory is mounted, the operation of the element may become impossible during data writing. In such a case, data to be written may not be correctly stored in the nonvolatile memory.

[0004] In order to manage the number of prints and the life of the print drum in the printer device, the print device is allocated to a non-volatile memory.
Normally, only one reserved counter is assigned for each function. Therefore, if the data to be written cannot be correctly stored in the non-volatile memory, a counter error is not detected even after that. The abnormal count value is updated and associated with the firmware. When the firmware processing is performed on the abnormal count value, the user is notified of the abnormal number of prints and the life of the print drum at the abnormal time.

[0005]

In order to solve the above-mentioned problems, a count value writing method according to the present invention provides a method of writing a count value into a plurality of areas of a nonvolatile memory in which an area storing the smallest value is the oldest value. The count value is sequentially written so as to recognize the area to be stored and to write the next count value to the area, and the maximum value of the values written to the plurality of areas is used as the count value, The abnormality of the counter is detected by detecting that the correlation has been broken, and the recovery process is performed when the abnormality of the counter is detected.

According to the present invention having the above-described structure, when writing a count value, the area storing the smallest value is recognized as the area storing the oldest value, and the next count value is written to the area. In this manner, the operation is sequentially performed on a plurality of areas of the nonvolatile memory. Then, the maximum value of the values written in the plurality of areas is set as the count value. If a device that implements the nonvolatile memory suddenly loses power and data is not correctly stored in the nonvolatile memory, a counter value is detected by detecting the collapse of the correlation between the multiple areas where the count value is written. It is determined to be abnormal, and if it is determined to be abnormal, recovery processing is performed and the count value is returned to a normal value.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram illustrating a configuration of a nonvolatile memory according to an embodiment, and FIG. 2 is a control block diagram according to the embodiment. In the present embodiment, a counter that counts the number of printed sheets in a printer will be described as an example.

In FIG. 2, a control unit 1 controls a printer, and a paper discharge detection sensor 2 and a nonvolatile memory 3 are connected to the control unit 1. Paper discharge detection sensor 2
Is to detect when printed paper is ejected,
The printing paper can be counted by counting the number of detections by the sensor 2. The non-volatile memory 3 is, for example, EE
This is a memory composed of a P-ROM and has a counter unit 4. The counter unit 4 is controlled by the control unit 1.

FIG. 1 shows a counter section. In FIG.
The counter unit 4 includes three areas a, b, and c. The control unit 1 controls the three areas a, b, and c to realize a count function, an abnormality detection function, and a count value recovery function. When the nonvolatile memory 3 is initialized, the three areas a, b, and c are all 0, and the control unit 1 writes the count values into the three areas a, b, and c. The next count value is written to the area having the smallest count value already written in the area. If the count values are the same in a plurality of areas, the area a> area b> area c has the next priority. Write the count value. In the example shown in FIG. 1, the next count value is written in area c. The written count value is the previously written count value + 1. Then, the largest value among the count values held in each area is the count value up to the present.

Table 1 shows the order in which the count values are written as described above.

[0011]

[Table 1]

Next, the updating process of the counter will be described. FIG. 3 is a flowchart showing a counter updating process. First, the storage area of the minimum value of the counter is searched (step S1). It is determined whether or not there are a plurality of storage areas for the minimum value (step S2). If there is a plurality, the area having the higher priority is selected (step S3). The priorities are set in advance as area a> area b> area c. Next, the count value is written in the selected area (step S4).

Next, the operation of detecting an abnormality by checking the counter will be described. FIG. 4 is a flowchart showing the counter check process. The counter check process is performed, for example, as a power-on process. As shown in FIG. 4, the initialization is performed after performing various types of initialization. However, when an update process of the counter value or the like occurs, the initialization can be performed before that.

FIG. 5 is a flowchart showing the abnormality detection processing in the counter check processing. The abnormality in the present embodiment is a case where the count value is not continuously held as shown in Table 1. First, counter abnormalities are classified into the following three types. That is, (1) when area b = 0 and area c = 0, but area a is neither 0 nor 1, (2) area c = 0, but not area a = 1 and area b = 2 Then, (3) when none of the following three patterns applies, (i) area a + 1 = area b and area a + 2 = area c (ii) area b + 1 = area c and area b + 2 = area a (iii) Area c + 1 = Area and Area c + 2 = Area b Next, the abnormality detection operation will be described with reference to the flowchart of FIG. First, in step S11, the control unit 1 checks whether or not the state (1) is established. That is, although area b = 0 and area c = 0, even if area a is 0, 1
If not, it is determined that there is an abnormality, and the process proceeds to the pattern-specific recovery processing in step S16. The abnormality in this case is referred to as abnormal pattern A. When the area b = 0, the area c = 0, and the area a is 0 or 1, it is determined that the area is normal. If the area b is not 0 or the area c is not 0, it is determined to be out of the pattern, and the process proceeds to the next step.

In step S12, it is checked whether or not the condition (2) is satisfied. That is, if the area c = 0 but not the area a = 1 and the area b = 2, it is determined to be abnormal, and the process proceeds to the pattern-specific recovery processing in step S16. The abnormality in this case is referred to as an abnormal pattern B. If area c = 0, area a = 1 and area b = 2, it is determined that the area is normal. If the area c is not 0, it is determined that the pattern is out of the pattern, and the process proceeds to the next step.

In step S13, it is checked whether or not the state of (3) (i) is satisfied. That is, area a + 1 = area b and area a + 2 = area c,
Is determined to be normal. If the area a + 1 is not equal to the area b, it is determined that the pattern is out of the pattern, and the process proceeds to the next step.

In step S14, (i) in (3) above
Check whether the condition is i). That is, when area b + 1 = area c and area b + 2 = area a, it is determined to be normal. Area b + 1 = area c
If not, it is determined to be out of the pattern, and the process proceeds to the next step.

In step S15, (ii) of (3) above
Check if the status is i). That is, area c
If + 1 = area a and area c + 2 = area b, it is determined to be normal, and if area c + 1 is not area a, it is determined to be abnormal, and the process proceeds to the pattern-specific recovery processing in step S16. The abnormality in this case is referred to as an abnormal pattern C.

Next, the recovery process for each pattern will be described. The restoration processing of the present embodiment is performed in the above-described abnormal patterns A, B, and C.
Perform according to. First, in the case of the abnormal pattern A, the area b = 0 and the area c = 0.
Is not the case, so in this case,
Area a = 1.

Next, in the case of the abnormal pattern B, the area c =
0, but not area a = 1 and area b = 2. The recovery process in this case will be described with reference to FIG. FIG. 6 is a flowchart showing the restoration process for each pattern.

First, it is determined whether or not area b = area a + 1 (step S21). When area b = area a + 1, area c = area b + 1 (step S2).
2). Next, it is determined whether or not area c = area b + 1 (step S23). When area c = area b + 1, area a = area c + 1 is set (step S24). Next, it is determined whether or not area a = area c + 1 (step S2).
5) When area a = area c + 1, area b = area a + 1 is set (step S26). When the area a is not equal to the area c + 1 in step S25, the initialization is performed as the restoration is impossible (step S27).

Next, in the case of the abnormal pattern C, the above (i)
Area a + 1 = Area b and Area a + 2 = Area c, (ii) Area b + 1 = Area c and Area b + 2
= Area a, (iii) area c + 1 = area a, and area c + 2 = area b, but the recovery process in this case is the abnormal pattern B shown in FIG.
Is the same as the processing in the case of

In the above embodiment, the next count value is written in the area holding the smallest count value among the count values held in the three areas, and the count value held in the three areas is changed. By making the largest count value among the present count values the current count value, a pointer pointing to the count area is not required for reading / writing the count value.

In the above embodiment, three areas have been described as an example. However, the counter may be configured using more areas. It is possible to easily increase the number of areas by associating the logic for detecting the abnormality of the counter and the corresponding recovery logic with n areas.

[0025]

As described above in detail, according to the present invention, the writing of the count value is sequentially performed in a plurality of areas of the nonvolatile memory in a cyclic manner, so that the equipment mounting the nonvolatile memory is unexpectedly provided. Even if data is not correctly stored in the non-volatile memory due to a power failure, the counter value is judged to be abnormal by detecting the collapse of the correlation between the multiple areas where the count value is written, and the abnormality is determined. If so, recovery processing is performed and the count value is returned to a normal value. Since the destruction of the count value due to the power cutoff occurs logically at only one place, the correlation between the count values is checked by software when the power is turned on. Can be determined to be abnormal. By performing recovery processing when it is determined that the count is abnormal, the count value is returned to a normal value.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating a configuration of a nonvolatile memory according to an embodiment;

FIG. 2 is a control block diagram of the embodiment.

FIG. 3 is a flowchart illustrating an abnormality detection process.

FIG. 4 is a flowchart showing a pattern-based recovery process.

FIG. 5 is a flowchart illustrating an abnormality detection process in the counter check process.

FIG. 6 is a flowchart showing a restoration process for each pattern.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Control part 3 Non-volatile memory 4 Counter part

Claims (2)

[Claims] 1. A method according to claim 1, wherein an area storing the smallest value is an area storing the oldest value and a next count value is written in the area. The count value is sequentially written, the maximum value of the values written in the plurality of areas is set as the count value, and the abnormality of the counter is detected by detecting that the correlation between the plurality of areas is broken. A recovery process performed when an abnormality is detected in a count value in a nonvolatile memory. 2. The method according to claim 1, wherein the restoration process is performed for each abnormal pattern.