JP5933294B2 - Cumulative value information management apparatus for vehicle and cumulative value information management method - Google Patents

Description

  The present invention relates to a vehicle cumulative value information management apparatus and a cumulative value information management method that can be used for applications such as an odometer mounted on a vehicle instrument panel or the like.

  Many vehicles such as automobiles are equipped with an odometer that displays the accumulated mileage from the time of manufacture of the vehicle to the present. For such an odometer, various ideas are required so that the correct mileage can always be displayed.

  In particular, in the case of a digital odometer that displays the mileage by electrical processing, it is necessary to consider that the distance data does not disappear even when the power supply from the vehicle is cut off. In addition, it is necessary to improve the reliability of data to be managed so that a large error does not occur in the displayed travel distance due to the occurrence of an error.

  Japanese Patent Application Laid-Open No. 2004-133867 discloses a conventional technique related to this type of digital odometer. As disclosed in Patent Document 1, this type of digital odometer uses a non-volatile memory to store mileage data. In addition, the data on the travel distance is held using memory areas of a plurality of addresses on the nonvolatile memory. Such special control can improve the reliability of the travel distance data.

Japanese Patent No. 2870679

  Conventional odometers for vehicles have conventionally been required to have a maximum displayable cumulative mileage of up to 1 million km. However, in recent years, there has been a market demand for increasing the maximum value of the cumulative mileage that can be displayed to 10 million km.

For example, assuming that a nonvolatile memory having a configuration of 16 bits (one word) per address is used, “65536” types of numerical values can be stored in the memory of one address. Accordingly, for example, assuming that a memory is used with 16 addresses and the sum of the memory values of each address is added to calculate the sum, the storable numerical value type D1 is expressed by the following equation.
D1 = 65,536 × 16 = 1,048,576

  In this case, assuming that the minimum unit of the numerical value of each memory area is “1 km”, the travel distance in the range of 0 km to 1048576 km can be stored. That is, it is possible to respond to a request to set the maximum value of the accumulated mileage that can be displayed to 1 million km.

If it is assumed that the maximum value of the accumulated mileage that can be displayed under the same conditions as described above is increased to 10 million km, it is necessary to use a memory with 160 addresses which is ten times the above. In this case, the numerical value type D2 that can be stored is expressed by the following equation.
D2 = 65,536 × 160 = 10,485,760

  That is, if the maximum value of the cumulative mileage that can be displayed is increased from 1 million km to 10 million km, the required capacity of the non-volatile memory increases 10 times. Therefore, a significant increase in the manufacturing cost of the odometer is inevitable.

  On the other hand, the nonvolatile memory is deteriorated by data rewriting. Therefore, it is necessary to limit the number of rewrites of each address of the nonvolatile memory in order to suppress the occurrence of a data error at the time of data writing to or reading from the nonvolatile memory. The upper limit of the number of rewrites is, for example, about 1 million times.

  However, for example, if it is intended to support the display of the travel distance up to 10 million km, when the distance data is updated every 1 km, the data update count becomes 10 million times at the maximum. Therefore, there is a possibility that the nonvolatile memory may be deteriorated, and it is not possible to withstand the display of the travel distance up to 10 million km.

  The present invention has been made in view of the above-described circumstances, and the object thereof is to achieve reliable operation without significantly increasing the required memory capacity even when a very large cumulative value is to be managed. It is an object of the present invention to provide a vehicle cumulative value information management apparatus and a cumulative value information management method capable of obtaining a highly cumulative value.

In order to achieve the above-described object, the vehicle cumulative value information management apparatus according to the present invention is characterized by the following (1) to ( 3 ).
(1) A vehicle cumulative value information management device that holds a cumulative value of measurement results detected on a vehicle and manages the cumulative value so as to be sequentially updated to the latest information,
A non-volatile storage for holding data;
A data management unit that accesses the nonvolatile storage unit and updates data held by the nonvolatile storage unit;
With
The nonvolatile storage unit is
A plurality of individual information memories each holding a numerical value representing a part of the cumulative value, a data area regularly arranged over a plurality of addresses,
A pointer area in which the same number of individual pointer information memories as the number of the individual information memories existing in the data area are regularly arranged over a plurality of addresses outside the data area;
Have
The data management unit manages a plurality of individual information memories in the data area and a plurality of individual pointer information memories in the pointer area in association with each other,
Each time the data management unit updates the data in the data area, the position of the memory to be updated of the stored contents is sequentially switched among the plurality of individual pointer information memories.
When updating the data in the data area, the data management unit updates and updates the stored contents of the individual pointer information memory in the next order with respect to the previously updated individual pointer information memory and stores the current data Updating the content stored in the individual information memory corresponding to the individual pointer information memory whose content has been updated;
The data management unit grasps the accumulated value based on storage contents of the plurality of individual information memories existing in the data area.
( 2 ) The vehicle cumulative value information management device configured as described in (1) above,
The data management unit considers an abnormal state and executes a predetermined special process when the storage content of the individual information memory of the data area exceeds a predetermined threshold.
( 3 ) A vehicle cumulative value information management device configured as described in (1) above,
The data management unit updates the stored contents of the data area each time a change in a predetermined value is detected in the measurement result.

According to the vehicle cumulative value information management apparatus having the configuration (1), since the numerical value representing the cumulative value is held in a state of being distributed to the plurality of individual information memories, the number of data updates to each individual information memory is reduced. And memory deterioration of the nonvolatile storage unit can be suppressed .
In addition, since a plurality of individual pointer information memories are provided, the number of times of data update of each individual pointer information memory can be reduced, and memory deterioration of the nonvolatile storage unit can be suppressed.
In addition, since the individual information memory to be updated and the individual pointer information memory are sequentially switched, the number of updates for these can be made uniform. For example, when n individual information memories and n individual pointer information memories are provided, the number of times each memory is updated can be reduced to the total (1 / n). Accordingly, it is possible to suppress memory deterioration of the nonvolatile storage unit.
According to the vehicle cumulative value information management apparatus having the above configuration ( 2 ), it is possible to detect an abnormal state before the number of updates of each individual information memory exceeds a threshold value and the memory deteriorates.
According to the vehicle cumulative value information management apparatus having the configuration ( 3 ), it is possible to reduce the number of times the stored contents of the data area are updated.

In order to achieve the above-mentioned object, the cumulative value information management method according to the present invention is characterized by the following ( 4 ).
( 4 ) A cumulative value information management method for maintaining a cumulative value of measurement results that are sequentially detected and managing the cumulative value so as to be sequentially updated to the latest information,
A plurality of individual information memories each holding a numerical value representing a part of the cumulative value, a data area regularly arranged over a plurality of addresses,
A pointer area in which the same number of individual pointer information memories as the number of the individual information memories existing in the data area are regularly arranged over a plurality of addresses outside the data area;
Are allocated on a predetermined nonvolatile storage unit,
Managing a plurality of individual information memories in the data area and a plurality of individual pointer information memories in the pointer area in association with each other;
Each time the data in the data area is updated, the position of the memory to be updated is sequentially switched among the plurality of individual pointer information memories,
When updating data in the data area, the storage contents of the individual pointer information memory in the next order are incremented with respect to the previously updated individual pointer information memory and updated this time, and the individual storage contents updated this time are updated. Increment and update the stored contents of the individual information memory corresponding to the pointer information memory,
Grasping the accumulated value based on the storage contents of the plurality of individual information memories existing in the data area.

According to the cumulative value information management method having the configuration of ( 4 ) above, since the numerical value representing the cumulative value is held in a state of being distributed to a plurality of individual information memories, the number of data updates to each individual information memory can be reduced. And memory degradation of the nonvolatile storage unit can be suppressed.
In addition, since a plurality of individual pointer information memories are provided, the number of times of data update of each individual pointer information memory can be reduced, and memory deterioration of the nonvolatile storage unit can be suppressed.
In addition, since the individual information memory to be updated and the individual pointer information memory are sequentially switched, the number of updates for these can be made uniform. For example, when n individual information memories and n individual pointer information memories are provided, the number of times each memory is updated can be reduced to the total (1 / n). Accordingly, it is possible to suppress memory deterioration of the nonvolatile storage unit.

  According to the vehicle cumulative value information management apparatus and the cumulative value information management method of the present invention, even if a very large cumulative value is a management target, the reliability is increased without significantly increasing the required memory capacity. A highly accumulative value can be obtained. For example, it is possible to manage a travel distance having an upper limit of about 10 million km.

  The present invention has been briefly described above. Further, the details of the present invention will be further clarified by reading through a mode for carrying out the invention described below (hereinafter referred to as “embodiment”) with reference to the accompanying drawings. .

FIG. 1 is a block diagram illustrating a configuration example of an electric circuit of the vehicle cumulative value information management device according to the embodiment. FIG. 2 is a schematic diagram illustrating a specific configuration example of each storage area allocated on the nonvolatile memory. FIG. 3 is a flowchart showing a main flow relating to the operation of the vehicular cumulative value information management apparatus shown in FIG. FIG. 4 is a flowchart showing details of the travel distance storing process shown in FIG. FIG. 5 is a flowchart showing details of the travel distance display process shown in FIG.

  Specific embodiments relating to the vehicle cumulative value information management apparatus and cumulative value information management method of the present invention will be described below with reference to the drawings.

<Device hardware configuration example>
A configuration example of an electric circuit of the vehicle cumulative value information management apparatus according to the present embodiment is shown in FIG. Specifically, the vehicle cumulative value information management apparatus shown in FIG. 1 constitutes an odometer 10 mounted on the instrument panel of the vehicle.

  The odometer 10 can manage and display the cumulative value (integrated value) of the mileage of the vehicle from the time the vehicle is manufactured to the present as a numerical value in km. In the present embodiment, the maximum travel distance of 10 million km can be managed. The odometer 10 can also be used as a trip meter that displays the mileage from an arbitrary time point designated by the user.

  As shown in FIG. 1, the odometer 10 includes a microcomputer (CPU) 11, a nonvolatile memory 12, a volatile memory (RAM) 13, a mileage calculation unit 14, a nonvolatile memory access unit 15, and distance data addition. Unit 16, mode switching unit 17, display unit 18, input / output unit (I / O) 19, and interfaces (I / F) 20 and 21.

  The microcomputer 11 executes various processes required for overall control of the odometer 10 by reading and executing a program incorporated therein in advance. Specific processing contents will be described later.

  The non-volatile memory 12 is a rewritable semiconductor memory that can hold data even when no power is supplied from the outside, and is configured by a flash memory, for example. The nonvolatile memory 12 has an upper limit on the number of times it can be rewritten. That is, when data rewrite is repeated, deterioration occurs, and there is a possibility that an error occurs during data writing or reading, or that data cannot be rewritten. The upper limit of the number of rewrites is assumed to be about 1 million times, for example.

  The volatile memory 13 is a semiconductor memory that can read and write data by accessing the microcomputer 11 or the like. The volatile memory 13 is used to store temporary data because data disappears when power supply is cut off.

  The travel distance calculation unit 14 performs a process for calculating the travel distance. The nonvolatile memory access unit 15 performs a special process for accessing the nonvolatile memory 12. The distance data adding unit 16 performs a process for adding the numerical value of the data used for calculating the distance every time the vehicle travels a predetermined distance.

  The functions of the travel distance calculation unit 14, the nonvolatile memory access unit 15, and the distance data addition unit 16 can be incorporated into the microcomputer 11, but the contents of the nonvolatile memory 12 (the travel distance It is necessary to take sufficient safety measures to prevent unauthorized rewriting of (value).

  The mode switching unit 17 switches various modes according to a user input operation. For example, as the contents to be displayed, the cumulative value of the travel distance and the measurement distance of the trip meter can be switched, or the measurement distance of the trip meter can be reset.

  The display unit 18 is a display capable of displaying a numerical value in units of “1 km” of a travel distance up to 10 million km, and is configured by a liquid crystal display, for example. The display unit 18 is connected to the microcomputer 11 via the input / output unit 19. The numerical value of the travel distance can be displayed on the display unit 18 by the control of the microcomputer 11.

  An electric signal of a distance pulse (also referred to as a vehicle speed pulse) is input to the interface 20 from the vehicle side. In this distance pulse, one pulse signal appears every time the transmission output shaft of the vehicle rotates by a predetermined amount. Therefore, the travel distance of the vehicle is proportional to the number of generated distance pulses. The microcomputer 11 counts the number of distance pulses input via the interface 20. From this count value, the travel distance of the vehicle can be grasped.

  A signal from a power source connected to an ignition (IGN) switch is applied to the input of the interface 21. The microcomputer 11 grasps the ignition on / off state via the interface 21.

<Configuration example of storage area>
FIG. 2 shows a specific configuration example of each storage area allocated on the nonvolatile memory 12 in order to hold the accumulated data of the travel distance.

  As shown in FIG. 2, a travel distance data area 12 a and a pointer area 12 b are provided on the nonvolatile memory 12. The travel distance data area 12a is composed of 20 individual information memories DM (1) to DM (20) that are continuously arranged. The pointer area 12b is composed of 20 individual pointer information memories PM (1) to PM (20) arranged continuously.

  Each of the individual information memories DM (1) to DM (20) is configured as a memory area of two addresses adjacent to each other on the nonvolatile memory 12. For example, the first individual information memory DM (1) is configured as a combination of a memory having an address “1” and a memory having an address “2”. The second individual information memory DM (2) is configured as a combination of a memory whose address is “3” and a memory whose address is “4”.

  In the present embodiment, the memory at each address of the nonvolatile memory 12 is configured by a memory that holds binary data (0/1) of 16 bits (in units of “word”). Accordingly, each of the individual information memories DM (1) to DM (20) configured by memories of two addresses can hold binary data having a 32-bit configuration.

  Binary data in a 32-bit configuration (“long” unit = 2 “word”) can represent a numerical value in a range from “0” to “4,294,967,295” in decimal notation. it can. In hexadecimal notation, the numerical value is in the range from “00000000” to “FFFFFFFF”.

  In FIG. 2, the contents of the memory at each address on the nonvolatile memory 12 are shown as 16-bit data in hexadecimal notation, that is, data in a range from “0000” to “FFFF”.

  Accordingly, each of the individual information memories DM (1) to DM (20) can store any numerical value in the range from “0” to “4,294,967,295” in decimal notation. In hexadecimal notation, the numerical value is in the range from “00000000” to “FFFFFFFF”.

  On the other hand, each of the individual pointer information memories PM (1) to PM (20) is configured as a memory area of one address on the nonvolatile memory 12. Accordingly, each of the individual pointer information memories PM (1) to PM (20) can store an arbitrary numerical value in a range from “0” to “65,535” in decimal notation. In hexadecimal notation, the numerical value is in the range from “0000” to “FFFF”.

  In the present embodiment, the number of individual information memories DM (1) to DM (20) (20) and the number of individual pointer information memories PM (1) to PM (20) are the same. Further, the 20 individual pointer information memories PM (1) to PM (20) are associated with the individual information memories DM (1) to DM (20), respectively.

  The contents of the individual pointer information memories PM (1) to PM (20) in the pointer area 12b should be processed in the 20 individual information memories DM (1) to DM (20) in the travel distance data area 12a. Used to indicate a specific location.

<Description of how to use the storage area>
An outline of a method of using the travel distance data area 12a and the pointer area 12b on the nonvolatile memory 12 shown in FIG. 2 will be described below.

<Initial value of memory>
For the individual information memories DM (1) to DM (20) in the travel distance data area 12a, the initial value is “FFFFFFFF” in hexadecimal notation (“−1” in decimal). The initial value of each of the individual pointer information memories PM (1) to PM (20) in the pointer area 12b is “FFFF” in hexadecimal notation (“−1” in decimal).

<Updating accumulated values to be stored>
Each time the latest cumulative value to be stored increases by one unit, specifically, every time the travel distance increases by “1 km”, the contents of any one of the individual information memories DM (1) to DM (20) are incremented (“ The content of the stored data is updated so as to increase by “+1”.

  Each time the contents of the mileage data area 12a are updated, the memory location to be updated is switched in order in the individual information memories DM (1) to DM (20). The pointer area 12b is used so that the memory position can be easily grasped. Specifically, the process is as follows.

  Each time the data in the nonvolatile memory 12 is updated, the content of the stored data is updated so that the content of any one of the individual pointer information memories PM (1) to PM (20) is incremented (increased by “+1”). . Further, the individual pointer information memories PM (1) to PM (20) for updating data are switched in order.

  That is, every time the travel distance increases by “1 km”, PM (1) update, PM (2) update, PM (3) update,... After the last PM (20) is updated, the update is repeated in the same manner by returning to the position of the first PM (1).

  In this case, as in the pointer area 12b shown in FIG. 2, the position of the boundary where the data contents are different in the individual pointer information memories PM (1) to PM (20) can be easily grasped. That is, in the example shown in FIG. 2, the second individual pointer information memory PM (2) is the memory location last updated. Here, since the individual pointer information memory PM (2) is associated with the second individual information memory (memory having addresses 3 and 4) DM (2), the update target in the travel distance data area 12a is designated as the individual information memory. It can be specified as DM (2). In this case, the data in the individual information memory DM (2) is incremented.

  By performing the processing as described above, the 20 individual information memories DM (1) to DM (20) in the travel distance data area 12a can be updated with equal frequency. That is, the number of data rewrites can be suppressed to (1/20) of the total number of updates. Also, for the pointer area 12b, the individual pointer information memories PM (1) to PM (20) can be updated with equal frequency, and the number of data rewrites can be suppressed to (1/20) of the total number of updates. Thereby, deterioration of the non-volatile memory 12 can be suppressed.

<Description of stored cumulative value>
When the processing as described above is performed, the original accumulated value is divided into a plurality of values, and a part of the accumulated value is stored in each of the 20 individual information memories DM (1) to DM (20).

  Therefore, the sum of the contents of the individual information memory DM (1), the contents of DM (2), the contents of DM (3),..., DM (20) becomes the original accumulated value. That is, by adding all the data of the 20 individual information memories DM (1) to DM (20), a numerical value of the stored travel distance can be obtained.

  However, in the example shown in FIG. 2, since the initial values of the individual information memories DM (1) to DM (20) are “−1” (“FFFFFFFF” in hexadecimal notation), DM (1) to DM (20) Need to be corrected so that “+1” is added to the numerical value of the data stored in each.

  In the example illustrated in FIG. 2, the contents of the individual information memories DM (1) and DM (2) are “00000000”, and the contents of DM (3) to DM (20) are “FFFFFFFF”. That is, the contents of DM (1) and DM (2) each correspond to the decimal number “1 km”, and the contents of DM (3) to DM (20) each correspond to the decimal number “0 km”. The total sum of these contents, that is, the travel distance is “2 km”.

<Address calculation>
In the example shown in FIG. 2, the first memory address of the travel distance data area 12a is “1”, and each of the individual information memories DM (1) to DM (20) occupies two adjacent addresses. Are arranged in order, ie regularly. The leading memory address of the pointer area 12b is “41”, and the individual pointer information memories PM (1) to PM (20) each occupy one address in order, that is, regularly. Yes.

Therefore, the memory addresses of the individual information memories DM (1) to DM (20) having a correspondence relationship with each of the individual pointer information memories PM (1) to PM (20) can be easily calculated as follows. .
Apt = Ax × 2-81 (1)
Apt: the address indicated by the pointer Ax: the address of the n-th individual pointer information memory PM (n) itself of interest

  For example, in the example shown in FIG. 2, in the individual pointer information memories PM (1) to PM (20) sequentially arranged in the pointer area 12b, the data is finally changed from the initial value “FFFF” to “0000”. It can be seen that the last updated memory is the second PM (2). That is, PM (2) can be specified by finding the boundary between “0000” and “FFFF” in which adjacent data are different.

In this case, since the address (Ax) of the last updated individual pointer information memory PM (2) is “42”, the address Apt indicated by the pointer is calculated as follows.
Apt = 42 × 2-81 = 3

  That is, at the timing of the situation as shown in FIG. 2, the second individual information memory DM (2) composed of the 16-bit memory with the address “3” and the 16-bit memory with the next address “4” is stored. What is necessary is just to select as a process target.

<Contents of processing of odometer 10>
<Main flow>
The main flow regarding the operation of the odometer 10 shown in FIG. 1 is shown in FIG. This operation is realized by the control of the microcomputer 11, the travel distance calculation unit 14, the nonvolatile memory access unit 15, and the distance data addition unit 16 illustrated in FIG. 1. When electric power is supplied to the odometer 10 from the power source on the vehicle side, the odometer 10 starts the operation of FIG. 3 and proceeds to the process of step S11.

  In step S11, the microcomputer 11 inputs a signal indicating ON / OFF of the ignition switch from the interface 21, and identifies ON / OFF. When turned on, the process proceeds to step S12.

  In step S <b> 12, the microcomputer 11 inputs a distance pulse signal from the interface 20, and performs a calculation process related to an increase in travel distance based on this signal. That is, the number of input distance pulses is counted. Since the count value is proportional to the travel distance, the count value can be converted into the travel distance using a predetermined constant. The microcomputer 11 detects an increase in travel distance based on the count value of the distance pulse detected in step S12, and processes this increase in the next step S13.

  In step S13, the data stored in the nonvolatile memory 12 is controlled by the microcomputer 11 so that the travel distance data held in the nonvolatile memory 12 reflects the latest increase in travel distance detected in step S12. Update. However, when data is actually updated in the nonvolatile memory 12, the nonvolatile memory access unit 15 and the distance data addition unit 16 perform control in order to prevent unauthorized data tampering. Details of step S13 will be described later.

  In step S14, the microcomputer 11 reads the travel distance data held in the non-volatile memory 12, grasps the cumulative value of the current travel distance based on this data, and displays the travel distance. Implement control. Details of step S14 will be described later.

<Details of mileage storage processing>
FIG. 4 shows details of the “travel distance storing process” shown in FIG. The process of FIG. 4 will be described below.

  In step S <b> 21, the microcomputer 11 takes in the count pulse data of the distance pulse detected in step S <b> 12 described above, that is, the increase in the travel distance as processing target data.

  In step S22, the microcomputer 11 identifies whether or not the increase in the travel distance captured in step S21 has reached “1 km” which is a measurement unit. When it reaches “1 km”, the process proceeds to the next step S23, and when it has not reached, this process is terminated. If the increase in travel distance reaches “1 km”, the count value of the counter used for counting the distance pulses is reset to 0 in step S12, or the count value obtained by subtracting “1 km” is subtracted. Update.

  In step S23, the microcomputer 11 increments (+1) and updates the y-th individual pointer information memory PM (y) in the pointer area 12b shown in FIG. The individual pointer information memory PM (y) to be processed is a memory existing at the next address of the last updated memory among the 20 individual pointer information memories PM (1) to PM (20) in the pointer area 12b. And However, in the initial state where there is no updated memory, the first memory is the processing target.

  For example, when traveling at a distance of “1 km” is first detected, the data of all the individual pointer information memories PM (1) to PM (20) is the initial value “FFFF”, so that the first individual The pointer information memory PM (1) is selected as PM (y).

  In addition, when traveling for a distance of “1 km” is detected for the second time, the data in the first individual pointer information memory PM (1) is “0000”, and the second individual pointer information memory PM (2) Is “FFFF”. Accordingly, the second individual pointer information memory PM (2) is selected as PM (y).

  Similarly, when traveling for a distance of “1 km” is detected for the third time, the data in the first and second individual pointer information memories PM (1) and PM (2) are “0000”, and the third The data of the individual pointer information memory PM (3) is “FFFF”. Therefore, the third individual pointer information memory PM (3) is selected as PM (y).

In step S23, the above-described specific individual pointer information memory PM (y) is updated so that the data is incremented once (+1).
For example, when traveling for a distance of “1 km” is first detected, the data of PM (1) to be processed is the initial value “FFFF” (decimal number “−1”). "(Decimal number" 0 "). Further, when traveling for a distance of “1 km” is detected for the second time, the data of the PM (2) to be processed is the initial value “FFFF”, so this data is updated to “0000”. For example, when the data of PM (y) is “0000”, the data of PM (y) is updated to “0001”. Similarly, when the data of PM (y) is “0001”, the data of PM (y) is updated to “0002”.

In step S24, the microcomputer 11 specifies the update target position of the current travel distance data area 12a using the contents of the pointer area 12b.
For example, it is assumed that the second individual pointer information memory PM (2) is updated from “FFFF” to “0000” in the step S23 executed immediately before, and the state is as shown in FIG. In this case, the position of the second individual information memory DM (2) having a correspondence relationship from PM (2), that is, the address “3” is specified. Actually, the address is specified by the following equation.
Apt = Ay × 2-81 (2)
Apt: address indicated by the corresponding PM (y) Ay: address of the y-th individual pointer information memory PM (y) of interest

  In step S25, the microcomputer 11 combines the 16-bit data of the address (Apt) specified in step S24 and the 16-bit data of the next address (Apt + 1) to generate 32 bits of one individual information memory DM. Treat as data.

  For example, in the state shown in FIG. 2, the address (Apt) of the pointer (PT) indicated by the pointer area 12b is “3”, so the data on the nonvolatile memory 12 is “3” and the data is “4”. And combine. That is, the storage area indicated by the pointer (PT) is handled as a 32-bit individual information memory DM (2).

  In step S26, the microcomputer 11 compares the numerical value of the data in the 32-bit individual information memory DM at the position indicated by the pointer (PT) with a predetermined threshold value. This threshold is a value for regulating the upper limit of the number of data updates. In the present embodiment, the threshold is set to “500,000”. This threshold value can be changed as needed. When the numerical value of the data in the individual information memory DM is equal to or smaller than the threshold value, the process proceeds to the next step S27, and when it exceeds the threshold value, the process proceeds to step S28.

In step S27, update processing is performed so that the contents of 32-bit data stored in one individual information memory DM to be processed this time are incremented once (+1) and increased.
For example, when the first individual information memory DM (1) is processed for the first time in step S27, the initial value “FFFFFFFF” (decimal number “−1”) is incremented to “00000000” (decimal number). ("0").

  Further, when the first individual information memory DM (1) is processed for the second time, the first update result “00000000” is updated to “00000001”. Similarly, when the first individual information memory DM (1) is processed for the third time, the second update result “00000001” is updated to “00000002”.

  Actually, every time the travel of “1 km” is detected, the position indicated by the pointer (PT) is switched (S23). Therefore, after updating the first individual information memory DM (1), DM (2), DM (3) Data of DM (4) is updated in order. Then, after the updating of the 20 individual information memories DM (1) to DM (20) is completed, the first individual information memory DM (1) is updated again by returning to the first position.

  Accordingly, each of the 20 individual information memories DM (1) to DM (20) is updated at an equal frequency.

In step S28, the microcomputer 11 identifies whether the address of the processing target memory is the final address. If it is not the final address, the process proceeds to step S19, and if it is the final address, the process proceeds to step S30. The “final address” corresponds to the address (39) of the 20th individual information memory DM (20) or the address (60) of the 20th individual pointer information memory PM (20).
That is, if the number of updates exceeds a threshold value (for example, 500,000 times) for all the individual information memories DM in the travel distance data area 12a, the process proceeds to step S30.

  In step S29, similarly to step S23, the microcomputer 11 switches the y-th individual pointer information memory PM (y) of interest in the pointer area 12b shown in FIG. The data in the individual pointer information memory PM (y) is incremented and updated.

  In step S30, the microcomputer 11 performs a predetermined “recording capacity over process”. That is, since the travel distance is recorded until the number of data updates in the nonvolatile memory 12 exceeds the upper limit value, it is processed as “recording capacity over”. Specifically, since the “recording capacity is exceeded”, the processing shown in FIG. 3 is stopped thereafter, or a special control such as blinking of the display on the display unit 18 is performed to issue a warning.

  For example, if the threshold value referred to in step S26 is set to “500,000”, “500,000” times for each of the 20 individual information memories DM (1) to DM (20) in the travel distance data area 12a. After the update, the “recording capacity over process” is executed in step S30. The number of updates exceeding this threshold corresponds to a travel distance of 10 million km.

<Details of mileage display processing>
FIG. 5 shows details of the “travel distance display process” shown in FIG. The process of FIG. 5 will be described below.

  In step S41, the microcomputer 11 specifies the range of the travel distance data area 12a existing on the nonvolatile memory 12 and the address of each individual information memory DM. In the example shown in FIG. 2, the number and position of 20 individual information memories DM (1) to DM (20) in the range of addresses “1” to “40” are specified. Further, it recognizes that the memory after the address “41” is not the individual information memory DM.

  Actually, the starting address “1” of the mileage data area 12a, the number of memory addresses “2” occupied by each individual information memory DM, the number “20” of the individual information memory DM, etc. are set as constants in the program in advance. As a result, all the individual information memories DM (1) to DM (20) can be specified.

In step S42, the microcomputer 11 reads the data stored from the nonvolatile memory 12 and calculates the current travel distance. For example, as shown in FIG. 2, when the mileage data area 12a is composed of 20 individual information memories DM (1) to DM (20), 20 individual information memories DM (1) to DM The stored data of each 32-bit configuration of (20) is read, and the travel distance is calculated based on these. The travel distance is calculated by the following equation.
Travel distance = total [km] of “numeric value represented by DM (1) data + 1” to “numeric value represented by DM (20) data + 1”

  In the example of FIG. 2, since the initial value of the data in each individual information memory DM is “−1” (FFFFFFFF), it is necessary to correct the numerical value by adding “+1” as in the above formula.

  In step S43, the microcomputer 11 outputs the numerical value of the travel distance acquired in step S42 to the display unit 18, and displays the travel distance so that it can be seen by the driver or the like.

<Advantages of odometer 10>
The odometer 10 described above can manage a mileage of up to 10 million km. Moreover, the number of addresses of the non-volatile memory 12 required is 60 in the example of FIG. 2, and the non-volatile memory 12 having a large memory capacity is not required. In addition, since the number of data rewrites in each individual information memory DM can be suppressed, malfunction due to deterioration of the nonvolatile memory 12 can be prevented. Furthermore, even if any individual information memory DM has a problem, it is possible to travel with a relatively low error and high reliability based on the regularity of data held in the plurality of individual information memories DM. The distance can be output.

<Possibility of deformation>
The configuration of the storage area shown in FIG. 2 is a representative example, and various modifications can be considered. For example, the number (20) of individual information memories DM constituting the travel distance data area 12a and the number (20) of individual pointer information memories PM constituting the pointer area 12b can be changed as necessary. In the example of FIG. 2, the individual information memory DM having the 32-bit configuration is configured by combining the memories of two adjacent addresses. However, the number (2) of the memories configuring the individual information memory DM is set as necessary. Can be changed.

  In the above-described embodiment, in order to be able to cope with a traveling distance of 10 million km, the threshold value indicating the upper limit value of the number of rewrites of each individual information memory DM is set to 500,000 times. The value can be changed as needed. For example, it is conceivable to increase the number (20) of individual information memories DM and lower the upper limit (500,000 times) of the number of rewrites.

  In the above-described embodiment, it is assumed that the present invention is applied to the odometer 10 for a vehicle. However, the present invention can be applied to various uses for handling large cumulative values in the same manner. For example, it can be used to manage a cumulative value of charging power, a cumulative value of discharging power, or a cumulative value of power consumption in the home in an electric vehicle.

<Supplementary explanation>
(1) The vehicle cumulative value information management device (10) includes a nonvolatile storage unit (12) and a data management unit (11, 15, 16). Further, as shown in FIG. 2, a plurality of individual information memories (DM (1) to DM (20)) each holding a numerical value representing a part of the accumulated value are stored on the non-volatile storage unit at a plurality of addresses. A data area (12a) regularly arranged over the pointer, and a pointer for holding specific address information related to the position of the last updated individual information memory among the plurality of individual information memories on the data area Area (12b). Further, the data management unit updates the storage contents of the individual information memory at the specific position and the specific address information held in the pointer area based on the specific address information held in the pointer area (S23, S27). Further, the data management unit grasps the accumulated value based on the storage contents of the plurality of individual information memories existing in the data area (S41, S42).

  (2) Further, as shown in FIG. 2, the pointer area (12b) includes a plurality of regularly arranged individual pointer information memories (PM (1) equal to the number of the individual information memories existing in the data area. ) To PM (20)). The data management unit manages the plurality of individual information memories in the data area and the plurality of individual pointer information memories in the pointer area in association with each other.

  (3) Also, as shown in FIG. 2, the data management unit allocates a storage area of a plurality of addresses on the nonvolatile storage unit to each individual information memory (DM) of the data area, and each individual information The memory position is grasped based on the contents of the corresponding individual pointer information memory (12b).

  (4) Further, the data management unit, when updating the data in the data area (12a), the memory to be updated among the plurality of individual information memories (DM (1) to DM (20)) Are sequentially switched (S23).

  (5) When the data management unit updates the data in the data area, the data management unit updates the location of the memory to be updated in the plurality of individual information memories, and the plurality of individual pointer information memories. The memory locations to be updated are sequentially switched (S23).

  (6) In addition, the data management unit determines that the stored contents of the individual information memory in the data area exceed a predetermined threshold value (for example, 500,000 times) (S26) and regards it as an abnormal state. A special process is executed (S30).

  (7) The data management unit updates the stored contents of the data area each time a change in a predetermined value (for example, a 1 km travel distance) is detected in a measurement result such as a travel distance (S22) (S27). ).

  (8) In the cumulative value information management method described above, a plurality of individual information memories each holding a numerical value representing a part of the cumulative value are arranged in a data area regularly arranged over a plurality of addresses, Among the plurality of individual information memories on the data area, a pointer area holding specific address information related to the position of the last updated individual information memory is allocated on a predetermined nonvolatile storage unit. Further, based on the specific address information held in the pointer area, the stored contents of the individual information memory at the specific position and the specific address information held in the pointer area are updated. Further, the cumulative value is grasped based on the storage contents of the plurality of individual information memories existing in the data area.

DESCRIPTION OF SYMBOLS 10 Odometer 11 Microcomputer 12 Non-volatile memory 12a Travel distance data area 12b Pointer area 13 Volatile memory 14 Travel distance calculation part 15 Non-volatile memory access part 16 Distance data addition part 17 Mode switching part 18 Display part 19 Input / output part 20, 21 Interface DM Individual information memory PM Individual pointer information memory

Claims (2)

A vehicle cumulative value information management device that holds a cumulative value of measurement results detected on a vehicle and manages the cumulative value so as to be sequentially updated to the latest information,
A non-volatile storage for holding data;
A data management unit that accesses the nonvolatile storage unit and updates data held by the nonvolatile storage unit;
With
The nonvolatile storage unit is
A plurality of individual information memories each holding a numerical value representing a part of the cumulative value, a data area regularly arranged over a plurality of addresses,
A pointer area in which the same number of individual pointer information memories as the number of the individual information memories existing in the data area are regularly arranged over a plurality of addresses outside the data area;
Have
The data management unit manages a plurality of individual information memories in the data area and a plurality of individual pointer information memories in the pointer area in association with each other,
Each time the data management unit updates the data in the data area, the position of the memory to be updated of the stored contents is sequentially switched among the plurality of individual pointer information memories.
When updating the data in the data area, the data management unit updates and updates the stored contents of the individual pointer information memory in the next order with respect to the previously updated individual pointer information memory and stores the current data Updating the content stored in the individual information memory corresponding to the individual pointer information memory whose content has been updated,
The said data management part grasps | ascertains the said cumulative value based on the memory content of these individual information memory which exists in the said data area. The cumulative value information management apparatus for vehicles characterized by the above-mentioned. A cumulative value information management method for maintaining a cumulative value of measurement results that are sequentially detected and managing the cumulative value so as to be sequentially updated to the latest information,
A plurality of individual information memories each holding a numerical value representing a part of the cumulative value, a data area regularly arranged over a plurality of addresses,
A pointer area in which the same number of individual pointer information memories as the number of the individual information memories existing in the data area are regularly arranged over a plurality of addresses outside the data area;
Are allocated on a predetermined nonvolatile storage unit,
Managing a plurality of individual information memories in the data area and a plurality of individual pointer information memories in the pointer area in association with each other;
Each time the data in the data area is updated, the position of the memory to be updated is sequentially switched among the plurality of individual pointer information memories,
When updating data in the data area, the storage contents of the individual pointer information memory in the next order are incremented with respect to the previously updated individual pointer information memory and updated this time, and the individual storage contents updated this time are updated. Increment and update the stored contents of the individual information memory corresponding to the pointer information memory,
The accumulated value information management method characterized by grasping the accumulated value based on the storage contents of the plurality of individual information memories existing in the data area.

Images