JPS60114711A - Electronic odometer - Google Patents

Abstract

PURPOSE:To elongate the writing life of a non-volatile memory maintaining accuracy, by making the writing running distance, which is updated in correspondence with an integrated running distance, variable, as a method for writing the integrated running distance data in the non-volatile memory. CONSTITUTION:A pulse signal is generated from a pulse generating part 1 with the running of a vehicle and counted by a counter 3. A program in an ROM 5 is executed in an MPU4. In correspondence with the counted number, the running distance and the integrated running distance of the vehicle are computed. The integrated running distance data is displayed on a digital display part 8. Upon the command from the MPU4, writing of the new integrated running distance data is performed in N pieces of integrated running distance data memory parts, which are provided as required for a non-volatile memory 7 for every variable specified running distance in correspondence with the integrated running distance up to now. When a power source is turned ON again or automatic resetting is performed, the data is read out. The data is written in an RAM6 and used as the integrated running distance data in the RAM6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an electronic odometer used in vehicles such as automobiles.

[Background of the invention]

Electronic odometers using non-volatile memory have been proposed as meters for measuring and displaying the cumulative mileage of vehicles such as automobiles (for example, Japanese Patent Laid-Open No. 55-95813) as an alternative to mechanical cumulative odometers. . This electronic odometer uses the car's battery as its power source and digitally displays the mileage data accumulated by the counter, but the accumulated mileage data is lost when the voltage drops or there is no voltage due to battery replacement or disconnection. In order to prevent this from occurring, cumulative mileage data is written in only one location in the non-volatile memo υ over and over again, for example, every 100 meters, and the data is read out and displayed. However, at present, there is a limit to the number of times that data can be written to non-volatile memory. It had the disadvantage that it could only be used up to a certain point. Also, as a way to alleviate this drawback,
Using non-volatile memory with several data storage locations,
A method has been proposed to reduce the number of writes to the same location. However, even in this case, there is a drawback that there is no margin for the writing life.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electronic odometer which eliminates the above-mentioned drawbacks of the prior art, extends the lifespan of a non-volatile memory, and has performance equivalent to or better than that of a mechanical meter.

[Summary of the invention]

The present invention provides a method for inputting vehicle mileage information and writing accumulated mileage data into a non-volatile memory by making variable the convolution mileage that is updated in accordance with the accumulated mileage. This is an electronic odometer that extends the write life of non-volatile memory while maintaining accuracy with respect to actual mileage.

[Embodiment of the Invention] An embodiment of the present invention will be explained below with reference to FIGS. 1 to 4.

@+": Figure 1 is a basic configuration block diagram showing an embodiment of an electronic odometer according to the present invention. In Figure 1,
1 is a pulse generator that generates pulse signals in accordance with the rotation of the wheels of the vehicle; 2 is a microcomputer that inputs and processes the pulse signals from the pulse generator 1; 3 is a human-powered pulse signal installed in the microcomputer 2; 4 is an MPU that performs arithmetic processing, 5 is a ROM that stores programs, 6 is a RAM that temporarily stores necessary data, 7 is a nonvolatile memory that stores cumulative mileage data, and 8 is a This is a digital display section.

Note that the non-volatile memory 7 is N1 to NN as necessary.
It is preferable to have a plurality of N cumulative mileage data storage locations.

With this configuration, the number of pulses of the pulse signal generated from the pulse generator 1 as the vehicle runs? microcomputer 3
Counter 3 counts, and the program in the LOMs is executed by the MPU 4.
The travel distance and cumulative travel distance of the vehicle are calculated according to the count ridges on the counter 3, and the resulting cumulative travel distance data is displayed on the digital display section 8, and
Fi is preferably stored in a plurality of N cumulative mileage data storage locations from N1 to NN provided as needed in the nonvolatile memory 7 for each predetermined mileage that is variable according to the cumulative mileage up to that point according to a command from the MPU 4. , sequentially update the address and write new cumulative mileage data,
Also, when the power is turned on again or when an auto-reset is performed, the data is read and written to RAM6.
It is used as cumulative mileage data for the M6.

FIG. 2 is a flowchart illustrating a main processing program in the microcomputer 2 of FIG. 1, FIG. 3 is a flowchart illustrating a conventional interrupt processing program for comparison, and FIG. 3 is a flowchart showing an example of a processing program. As shown in FIG. 2, the reading process of the cumulative mileage data in the non-volatile memory 7 is performed only at the initial time, and as shown in FIG. The running distance is calculated, and the predetermined running distance is calculated and displayed (latch) for each fixed running distance, for example, 100 meters.

While a write command is issued without setting a write flag, the write flag is reset after the write process is performed in the main process shown in Figure 2, whereas the write flag is reset as shown in Figure 4. In the embodiment of the invention, the running distance is calculated by counting the number of pulses of the pulse signal from the pulse generator 1 in the interrupt processing, and when the cumulative running distance is, for example, 1.
Up to 100km, the cumulative mileage is calculated every 100m.

Display (latch), write flag set, etc. are performed to issue a write command, but if the cumulative mileage is from 1100k to 11000k, a write command will be issued every m, and if the cumulative mileage is 11000k or more, a write command will be issued every 10km. Issue a write command to the second
In the main process shown in the figure, writing to the non-volatile memory 7 is preferably performed by sequentially updating addresses in a plurality of N cumulative mileage data storage locations from N+ to NN as necessary.

According to the above-described embodiment P of the present invention, the difference between the cumulative mileage data and the median mileage is small, and while sufficient accuracy is ensured, the number of writes to the nonvolatile memory can be reduced, extending its life. become.

〔Effect of the invention〕

As explained above, according to the electronic odometer of the present invention, the life of the non-destructive memory can be extended, and performance equivalent to or better than that of a t-stock meter can be ensured.

[Brief explanation of drawings]

FIG. 1 is a basic configuration block diagram showing one embodiment of the electronic odometer according to the present invention, FIG. 2 is a flowchart of the main processing program shown in FIG. 1, and FIG. 3 is a flowchart of the conventional interrupt processing program shown in FIG. , 8134 is a flowchart showing an embodiment of the interrupt processing program of the present invention shown in FIG.

Claims (1)

[Scope of Claims] 1. Means for calculating cumulative mileage by inputting regular distance information, non-volatile memory for storing the cumulative mileage data, and 1-inclusive mileage updated according to the cumulative mileage data. an electronic odometer comprising means for writing updated cumulative mileage data into the nonvolatile memory by making the distance variable. 2. The non-volatile memory is at least one non-volatile memory having a plurality of cumulative mileage data storage locations, and the reading means refreshes the cumulative mileage data storage locations and updates the above. 2. An electronic odometer according to claim 1, comprising means for writing cumulative mileage ^I data into said nonvolatile memory.