JP3867604B2 - Vehicle mileage accumulator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicular mileage accumulator equipped with a nonvolatile memory for storing a mileage accumulated value.
[0002]
[Background Art and Problems to be Solved by the Invention]
Conventionally, in this type of mileage accumulator, a mileage accumulated value as a total mileage is written and updated in a nonvolatile memory such as an EEPROM, and a liquid crystal panel or the like is based on the accumulated value thus stored. The integrated value is displayed on the display means.
[0003]
By the way, the mileage integrated value stored in the EEPROM is important for grasping how the vehicle has been used. For example, in the used car market, cars with a short total travel distance are popular, and such cars are often traded at high prices. For this reason, in order to increase the value when buying and selling as a used car, a situation has arisen in which the mileage integrated value stored in the EEPROM is rewritten to a small value and falsified.
[0004]
However, conventionally, since the mileage integrated value is simply stored in the EEPROM as it is, if any of the displayed mileage integrated value and the stored contents of each address of the EEPROM are compared, any of the EEPROM addresses is compared. It becomes easy to know whether the accumulated travel distance value is stored in the address, and as a result, the illegal tampering can be easily performed.
[0005]
In view of the above points, an object of the present invention is to make it difficult to tamper with the stored travel distance integrated value in a travel distance accumulator provided with a nonvolatile memory for storing the travel distance integrated value.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, there is provided a microcomputer (50), a rewritable nonvolatile memory (60) for storing a vehicle mileage integrated value, a drive circuit (70), and the drive circuit. A vehicle mileage accumulator comprising display means (40) driven to display at (70), wherein the microcomputer (50) encrypts the vehicle mileage accumulated value with a key code. wherein stored in the nonvolatile memory (60), when displaying the accumulated value on the display unit (40) through said drive circuit (70), the stored in the nonvolatile memory (60), and wherein encrypted integrated value decrypted by the key code, characterized in that to display on the basis of the decoded integrated value.
[0007]
Thereby, since the mileage integrated value stored in the non-volatile memory (60) is encrypted with the key code, the mileage integrated value displayed on the display means (40) and the non-volatile memory (60) Comparing the stored contents of each address, it is not easy for a tamper to determine which of the addresses of the non-volatile memory (60) stores the accumulated value unless it is decoded by a key code. it can. Therefore, it is difficult to illegally tamper with the mileage integrated value stored in the nonvolatile memory (60) by rewriting it to a small value.
[0008]
Further, in the present invention, when the travel distance integrated value is displayed on the display means (40), the encrypted integrated value is decrypted with the key code and displayed based on the decrypted integrated value. The present invention can be realized without impairing the original function of the travel distance accumulator such as displaying the travel distance integrated value.
[0009]
As for the key code, the key code may be stored in advance in the nonvolatile memory (60) as in the invention described in claim 2, or mounted on the vehicle as in the invention described in claim 3. The key code may be generated by the key code generating means (200).
[0010]
According to a fourth aspect of the present invention, the microcomputer (50), the rewritable nonvolatile memory (60) for storing the vehicle mileage integrated value, the drive circuit (70), and the drive circuit (70) Display means (40) for display drive is provided , and the microcomputer (50) reads the vehicle mileage integrated value stored in the nonvolatile memory (60) and displays the value via the drive circuit (70). Means (40) for displaying the travel distance integrated value, updating the travel distance integrated value as the vehicle travels, and displaying the updated travel distance integrated value on the display means (40) a travel distance totalizer, the microcomputer (50), the travel distance integrated value of vehicles, together with the key code obtained by converting the travel distance integrated value the Being adapted to be stored in the volatile memory (60), said memory to said non-volatile memory of the updated traveling distance integrated value (60), the traveling stored in the nonvolatile memory (60) Permitted only when the code obtained by converting the distance integrated value in the same manner as the conversion matches the key code stored in the nonvolatile memory (60) together with the travel distance integrated value. It is characterized by that.
[0011]
This makes it impossible for an unauthorized tamper who does not know the key code to rewrite the mileage accumulated value stored in the non-volatile memory (60), and therefore the mileage accumulated in the non-volatile memory (60). It is difficult to tamper with the value by rewriting it to a smaller value.
[0012]
Further, as in the invention described in claim 5, if the key code is set to a different code for each vehicle, even if the key code is known to a falsifier, in a plurality of vehicles. The risk of the tampering described above can be avoided.
[0013]
In addition, the code | symbol in the bracket | parenthesis of each said means is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0015]
(First embodiment)
This embodiment is an embodiment in which the mileage accumulator according to the present invention is applied to a passenger car meter. FIG. 1 is a front view of the instrument, and this instrument is disposed on the instrument panel of the passenger car as a combination meter.
[0016]
The instrument includes a speedometer S, a tachometer T, a shift indicator I, and an electronic mileage accumulator D. The speedometer S indicates the vehicle speed of the passenger car with the dial plate 10 and the pointer 20, and the dial plate 10 is provided on the opening 31 a of the bottom wall 31 of the annular facing plate 30 from the back side. .
[0017]
The mileage accumulator D is provided with a liquid crystal panel 40 as display means, and the liquid crystal panel 40 is provided on the opening 11 of the dial 10 from the back side. The liquid crystal panel 40 digitally displays an integrated value of the travel distance of the passenger car as a total travel distance.
[0018]
FIG. 2 is a block diagram of the travel distance accumulator D. The travel distance accumulator D includes a microcomputer 50, an EEPROM 60, and a drive circuit 70. The microcomputer 50 is composed of a CPU, a ROM, and the like, and starts executing based on a computer program stored in advance in the ROM under the operation of the ignition switch IG of the passenger car. Moreover, the microcomputer 50 is directly supplied with power from the battery Ba mounted on the passenger car and is maintained in an operating state.
[0019]
Further, the vehicle speed sensor Sv uses a vehicle speed sensor of the speedometer S, and the vehicle speed sensor Sv detects the vehicle speed of the passenger car.
[0020]
The EEPROM 60 is one of rewritable nonvolatile memories, and the EEPROM 60 writes and updates the integrated value of the travel distance of the passenger car under the control of the microcomputer 50. Incidentally, in the present embodiment, values from 0 km to 999,999 km are set to be writable.
[0021]
In the present embodiment configured as described above, the microcomputer 50 is in an operating state by receiving power directly from the battery Ba, and executes a computer program according to the flowcharts of FIGS. 3 and 4. Then, in a state where the ignition switch IG is not yet turned on, the determination of NO is repeated in step S10.
[0022]
When the ignition switch IG is turned on, processing in steps S20 to S50, which will be described in detail later, is performed, and the read travel distance integrated value A is displayed as display data and output to the drive circuit 70. Under the display drive by 70, the mileage integrated value A read out is displayed on the liquid crystal panel 40.
[0023]
Thereafter, when the passenger car is in a traveling state, the travel distance of the passenger car is integrated in accordance with the detection output of the vehicle speed sensor Sv in step S60, and the integrated value A is processed as display data in step S70. (Ie, display processing) and output. Therefore, the liquid crystal panel 40 displays the accumulated travel distance value at the current stage under display drive by the drive circuit 70.
[0024]
In addition, after the processing in step S70, in step S80, the writing update processing of the mileage integrated value A to the EEPROM 60 is executed according to the flowchart of FIG. Incidentally, in this embodiment, the upper limit value of the travel distance integrated value is set to 999,999 km.
[0025]
Next, in step S81 shown in FIG. 4, the key code K stored in advance in the ROM or the like of the microcomputer 50 is read out. The key code K is set to a different code for each vehicle. For example, the date of manufacture of the vehicle, the vehicle frame number, the key number used in the vehicle anti-theft device, and other individual vehicle information are provided. It is suitable for use.
[0026]
Next, in step S82, the integrated value A calculated in step S60 is encrypted with the key code K read in step S81. As a specific example, when the encrypted integrated value is A ′, the integrated value A is encrypted to A ′ so that A ′ = K × A.
[0027]
Next, in step S83, the encrypted integrated value A ′ is written in the EEPROM 60 and updated. Here, the integrated value A ′ is not simply written in the EEPROM 60 as it is, but is written under a specific conversion. For example, if the data holding area is 4 bytes, the first byte is added from 00H, the second byte is subtracted from ffH, the third byte is added from 00H, and the fourth byte is written as subtracted from ffH. ing.
[0028]
If the ignition switch IG remains on at the current stage when the write process in step S83 is completed and the process in step S80 is completed, each step S60 to S90 is performed after the determination of NO in step S100. The circulating process is repeated. Thereby, the display content of the liquid crystal panel 40 is repeatedly updated, and the value written to the EEPROM 60 is repeatedly updated.
[0029]
Thereafter, when the ignition switch IG is turned off, the computer program returns to step S10. As the ignition switch IG is turned off, the contents written to the EEPROM 60 are stored and maintained even after the ignition switch IG is turned off.
[0030]
When the ignition switch IG is turned on in step S10, the encrypted value A ′ is obtained by performing the reverse conversion to the conversion in step S83 on the data written in the EEPROM 60 in step S20. read out.
[0031]
Next, in step S30, the key code K is read from the ROM, and in step S40, it is determined whether or not the encrypted integrated value A ′ can be decrypted with the key code K. As a specific decoding method, in this embodiment, the result of dividing the integrated value A ′ by the key code K is decoded as the travel distance integrated value A.
[0032]
If there is a remainder in the division result, it is determined in step S40 that decoding is impossible, an error message is displayed on the liquid crystal panel 40 in step S45, and the process returns to step S10.
[0033]
On the other hand, if there is no remainder, the process proceeds to step S50, where the decoded integrated value A is displayed as display data and output to the drive circuit 70 as described above, and the travel distance integrated value is displayed on the liquid crystal panel 40. A is displayed.
[0034]
As described above, according to the present embodiment, since the mileage integrated value A is encrypted with the key code K and stored in the EEPROM 60, the mileage integrated value displayed on the liquid crystal panel 40 and the stored contents of each address of the EEPROM 60 are stored. Even if the comparison is made, it is not easy for the tamper to know which address of the EEPROM 60 address the accumulated value is stored in unless it is decoded by the key code K. Therefore, it is possible to make it difficult to illegally tamper with the mileage integrated value stored in the EEPROM 60 by rewriting it to a small value.
[0035]
In the present embodiment, when the integrated value A is displayed on the liquid crystal panel 40, the encrypted integrated value A ′ is decrypted with the key code K and displayed based on the decrypted integrated value A. Therefore, it is needless to say that the present embodiment can be realized without impairing the original function of the mileage accumulator D that displays the mileage accumulated value A.
[0036]
In the present embodiment, since the key code K is set to a different code for each vehicle, even if the key code K is known to a tamper, the falsification is performed in a plurality of vehicles. The risk of being done can be avoided.
[0037]
(Second Embodiment)
In the first embodiment, the key code K is stored in advance in the ROM of the microcomputer 50. However, in this embodiment, the vehicle is provided with an ECU as a key code generating means. A different key code K is generated for each vehicle. Then, the generated key code K is decrypted in step S40 in FIG. 3 and encrypted in step S82.
[0038]
FIG. 5 is a block diagram showing various on-vehicle electronic control devices (hereinafter referred to as ECUs) 100, 200, 300, 400 according to the present embodiment. The ECU 100 is a meter ECU including the microcomputer 50, the EEPROM 60, the drive circuit 70, and the like shown in FIG. 2, and the ECU 200 is the above-described key code generation ECU. ECU 300 is a navigation ECU that controls the operation of a navigation device mounted on the vehicle, and travel distance integrated value AECU 400 is an air conditioner ECU that controls the operation of the vehicle air conditioner.
[0039]
The ECUs 100 to 400 can communicate with each other via an in-vehicle LAN or the like, and the key code generation ECU 200 transmits a key code K to each ECU 100, 300, 400. As described above, meter ECU 100 performs decryption in step S40 and encryption in step S82 with the received key code K.
[0040]
Here, the navigation ECU 300 includes control means that is executed based on the travel distance integrated value A calculated by the meter ECU 100. Then, for navigation ECU300 is integrated value A which is encrypted by the meter ECU100 decoding the 'receives the integrated value A received by the key code transmitted from the key code generating ECU 200'. Then, the control means is executed based on the decoded integrated value A.
[0041]
As described above, according to the present embodiment, since the mileage integrated value A is encrypted with the key code K and stored in the EEPROM 60, the same effect as in the first embodiment can be exhibited.
[0042]
Further, according to the present embodiment, not only the meter ECU 100 but also the other ECUs 300 and 400 receive the encrypted integrated value A ′ and decrypt it with the key code K. It is possible to prevent the integrated value A that has not been converted from being known by an unauthorized tamper from other ECUs 300, 400, etc. Further, since the encrypted integrated value A ′ is communicated between the ECUs 100 to 400, the unencrypted integrated value A is known by the unauthorized tamper from other ECUs 300, 400, etc. Can be prevented.
[0043]
Note that the present invention can be implemented as long as the vehicle includes at least the meter ECU 100 and the key code generation ECU 200 among the ECUs 100 to 400.
[0044]
(Third embodiment)
This embodiment has the same hardware configuration as that of the first embodiment. In the first and second embodiments, the travel distance integrated value A is encrypted with the key code K and stored in the EEPROM 60. In the present embodiment, the travel distance integrated value A0 is The key code K0 associated with the integrated value A0 is stored in the EEPROM 60 as a non-volatile memory. Then, storage of the updated travel distance integrated value A1 in the EEPROM 60 is permitted only when the integrated value A0 used for association matches the key code K0.
[0045]
Specifically, the microcomputer 50 executes a computer program according to the flowcharts of FIGS. 6 and 7. Then, in a state where the ignition switch IG is not yet turned on, the determination of NO is repeated in step S10.
[0046]
When the ignition switch IG is turned on, the integrated value A stored in the EEPROM is read in step S21, the travel distance integrated value A read in step S50 is displayed as display data, and output to the drive circuit 70. Then, the driving distance integrated value A read out is displayed on the liquid crystal panel 40 under display driving by the driving circuit 70.
[0047]
Thereafter, when the passenger car is in a traveling state, the travel distance of the passenger car is integrated in accordance with the detection output of the vehicle speed sensor Sv in step S60, and the integrated value A is processed as display data in step S70. (Ie, display processing) and output. Therefore, the liquid crystal panel 40 displays the accumulated travel distance value at the current stage under display drive by the drive circuit 70.
[0048]
In addition, after the process in step S70, the write update process shown in the flowchart of FIG. 7 is performed in step S90. Here, in this embodiment, for example, the travel distance integrated value A is periodically updated and stored in the EEPROM 60 at a time interval of 10 msec.
[0049]
That is, in step S901, if the current timing is not the above 10 msec timing, the routine S90 is terminated without writing update, and if it is 10 msec timing, the process proceeds to step S902, and the EEPROM 60 is transferred to the EEPROM 60 in step S911 described later. The written key code K is read out and stored in the RAM of the microcomputer 50.
[0050]
Next, in step S903, the travel distance integrated value A written in the EEPROM 60 in step S910 described later is read and stored in the RAM.
[0051]
Next, in step S904, the integrated value A stored in the RAM is converted into a code B using an arbitrary conversion formula. As a specific example of the conversion formula, there is a SUM code or the like that handles 2 digits of the integrated value as a 1-byte hexadecimal number. According to this SUM code, for example, when the integrated value A is 123,456 km, an operation of 0x12 + 0x34 + 0x56 is performed, and this operation result 0x9C is set as a code B.
[0052]
Next, in step S905, code B is converted into code C based on the code conversion table created with an arbitrary value. This code conversion table is preferably created using, for example, a random number table, and FIG. 8 is a table showing an example of the code conversion table. According to this conversion table, for example, when the code B is 0x02, the code C is set to 0xAB.
[0053]
Next, in step S906, the key code K read in step S902 is compared with the code C converted in step S905. If the two codes K and C are different, then in step S903. Assuming that the read integrated value A is abnormal, an abnormality process is performed in step S907. For example, ERROR or the like is displayed on the liquid crystal panel 40.
[0054]
On the other hand, if the two codes K and C match in step S906, the process proceeds to step S908, and the conversion in step S904 is performed on the value A1 (for example, 123,457 km) to be updated and written from the integrated value A this time. The code B1 is calculated using the formula. In step S909, the code C1 is calculated for the code B1 using the conversion table in step S905.
[0055]
Next, in step S910, the integrated value A stored in the EEPROM 60 is updated and written to the integrated value A1. Thereafter, in step S911, the value of the key code K stored in the EEPROM 60 is updated and written to the value of the code C1, and the write update processing flow in step S90 is ended.
[0056]
If the ignition switch IG remains on at the current stage after step S90 is completed, the process of circulating through steps S60, S70, S90, and S100 is repeated after determining NO in step S100. Thereby, the display content of the liquid crystal panel 40 is repeatedly updated, and the value written to the EEPROM 60 is repeatedly updated.
[0057]
Thereafter, when the ignition switch IG is turned off, the computer program returns to step S10. As the ignition switch IG is turned off, the contents written to the EEPROM 60 are stored and maintained even after the ignition switch IG is turned off.
[0058]
As described above, according to the present embodiment, the travel distance integrated value A is stored in the EEPROM 60 together with the key code C associated with the integrated value A, and the updated travel distance integrated value A1 is stored in the EEPROM 60. It is permitted only when the integrated value A and the key code C used for the association match. Therefore, since the mileage integrated value stored in the EEPROM 60 cannot be rewritten by an unauthorized tamper who does not know the key code, the mileage integrated value stored in the EEPROM 60 is rewritten to a small value and illegally falsified. Can make it difficult.
[0059]
(Other embodiments)
In the second embodiment, the travel distance integrated value A is periodically stored and updated in the EEPROM 60 based on the determination in step S901. However, when the present invention is carried out, the stored distance is updated irregularly. Of course, it may be.
[0060]
In the first embodiment, the key code K is set to a different code for each vehicle. However, a key code K common to all vehicles may be used in implementing the present invention. In carrying out the present invention, the conversion formula in step S904 and the code conversion table in step S905 of the second embodiment may be different for each vehicle, or common to all vehicles. It may be.
[Brief description of the drawings]
FIG. 1 is a front view of a passenger car instrument showing a first embodiment in which a mileage accumulator of the present invention is applied to a passenger car instrument.
FIG. 2 is a block diagram of a mileage accumulator shown in FIG.
FIG. 3 is a flowchart showing the operation of the microcomputer shown in FIG. 2;
4 is a detailed flowchart of a write update processing step shown in FIG. 3;
FIG. 5 is a block diagram of a mileage accumulator according to a second embodiment of the present invention.
FIG. 6 is a flowchart showing the operation of the microcomputer according to the third embodiment of the present invention.
FIG. 7 is a detailed flowchart of a write update processing step shown in FIG. 6;
8 is a chart showing an example of a code conversion table used in the flowchart of FIG.
[Explanation of symbols]
40 ... Liquid crystal panel (display means), 60 ... EEPROM (nonvolatile memory).

Claims (5)

A microcomputer (50), a rewritable nonvolatile memory (60) for storing an accumulated mileage value of a vehicle, a drive circuit (70), and display means (40) driven by the drive circuit (70). A vehicle mileage accumulator,
The microcomputer (50), the travel distance integrated value of the vehicle, and encrypted by the key code is stored in the nonvolatile memory (60), said display means via said drive circuit (70) said integrated value In the case of displaying in (40), the encrypted integrated value stored in the nonvolatile memory (60) and decrypted by the key code is displayed based on the decrypted integrated value. A vehicle mileage accumulator characterized by the following. The vehicle mileage accumulator according to claim 1, wherein the key code is stored in advance in the nonvolatile memory (60). The vehicle mileage accumulator according to claim 1, wherein the key code is generated by a key code generating means (200) mounted on the vehicle. A microcomputer (50), a rewritable nonvolatile memory (60) for storing an accumulated mileage value of a vehicle, a drive circuit (70), and display means (40) driven by the drive circuit (70). The microcomputer (50) reads the vehicle travel distance integrated value stored in the non-volatile memory (60) and supplies the travel distance integrated value to the display means (40) via the drive circuit (70). A vehicle mileage accumulator for displaying the updated mileage integrated value as the vehicle travels and displaying the updated mileage integrated value on the display means (40) ,
The microcomputer (50), the travel distance integrated value of vehicles are adapted to be stored in the nonvolatile memory together with the key code obtained by converting the travel distance integrated value (60),
The updated travel distance integrated value stored in the nonvolatile memory (60) is obtained by converting the travel distance integrated value stored in the nonvolatile memory (60) in the same manner as the conversion. And a vehicle mileage accumulator that is permitted only when the key code stored in the nonvolatile memory (60) matches the mileage accumulated value . The vehicle mileage accumulator according to any one of claims 1 to 5, wherein the key code is set to a different code for each vehicle.

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