JPH08271281A - Electronic odometer - Google Patents

Abstract

PURPOSE: To prevent the false display of a running distance owing to defective storage data of a nonvolatile memory or defective readout caused by the failure of the interface of a circuit, in an electronic odometer equipped with the nonvolatile memory holding distance data even when a power source is opened. CONSTITUTION: This odometer comprises a distance computing means 2 which counts and computes pulse signals sent from a distance detecting means 1, a holding means 3 which holds a determined running distance in an updating manner, a display unit 5 displaying the running distance and a control means 6 which makes a nonvolatile memory 7 store the running distance determined at a prescribed timing and outputs the stored data to the distance computing means 2. The nonvolatile memory 7 has a running distance storage area and a check area and construction is so made that prescribed numerical data are stored beforehand in the check area and that these numerical data are read out prior to distance data and subjected to determination as to whether they are in accord with a predetermined value or not.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic odometer and, more particularly, to detection of malfunction of stored mileage data in a non-volatile memory when reading data.

[0002]

2. Description of the Related Art When a conventional electronic odometer is used as, for example, an odometer of a vehicle, it is necessary to keep the past mileage even if a battery abnormality (voltage drop, disconnection, etc.) occurs. , Non-volatile memory is used.
(JP-A-57-198810 and 59-1964).
14).

As a method of storing the traveling distance in this kind of electronic odometer, it is obtained by counting the pulse signals from the distance detecting means for each predetermined unit traveling distance in a plurality of addresses of the nonvolatile memory. There are some types that store the latest updated retention data sequentially, and some that store this retained data when the ignition switch is off.There is a configuration in which the latest stored data in the non-volatile memory is read out when the ignition switch is on, and the data is updated and displayed based on this. It is common. Further, even when the holding means for updating and holding the traveling distance, for example, the held data in the RAM is destroyed for some reason, the stored data in the non-volatile memory is read out and written in the RAM to restore the normal condition.

[0004]

In the prior art, however, the stored data in the non-volatile memory may change bits due to some noise or the like and become garbled data. Therefore, such a bit error is invalidated for correct running. Proposed a method to obtain only stored data of distance (Japanese Patent Publication No. 1-4
However, if there is an abnormality (such as an interface failure) in the read / write processing itself to the holding means, the stored data in the non-volatile memory may not be read correctly, and erroneous reading may occur. There remains a problem that the defective data due to the processing is transferred to the holding means as correct data and the subsequent update of the traveling distance becomes defective.

According to the present invention, the defective data due to the storage abnormality of the non-volatile memory itself is also inspected, and the defective data due to the read processing abnormality such as the interface failure is also similarly inspected so that the defective data is not used by mistake. The purpose is to do so.

[0006]

DISCLOSURE OF THE INVENTION The present invention provides a distance calculating means for counting a pulse signal from a distance detecting means to calculate a running distance, a holding means for updating and holding the running distance of the distance calculating means, and The nonvolatile memory includes a display for displaying the updated and held traveling distance, and a control means for storing the traveling distance in a non-volatile memory at a predetermined timing or outputting the stored data to the distance calculating means for updating. Is provided with a mileage storage area for storing the calculated mileage and a check area for storing predetermined numerical data, and the control means precedes the check when reading the mileage of the storage area. It is characterized in that the numerical data of the area is read and whether or not it matches a predetermined numerical value stored in advance is inspected.

The check area is composed of a plurality of addresses each having a predetermined number of bits, and the same numerical data is stored in each address. The control means takes a majority decision for each common bit of each address. It is characterized in that it is determined whether or not the obtained numerical value is numerical data stored in advance.

[0008]

[Function] By reading the predetermined numerical data stored in advance from the check area of the non-volatile memory and judging the numerical value, the change to the defective data in the non-volatile memory or the change to the defective data due to the reading processing error can be performed. Since it can be detected, it is possible to prohibit the adoption display of defective data due to the same garbled bit of the traveling distance data stored in the traveling distance storage area.

[0009]

1 shows a typical block diagram of an electronic odometer according to the present invention, in which a pulse signal generated from a distance detecting means 1 for each predetermined traveling distance according to the traveling of a vehicle is a distance. The traveling distance of the vehicle is accumulated by counting up the input pulse signals input to the arithmetic means 2 and performing arithmetic operations. The distance calculation means 2 can be achieved by a combination in a counter circuit, but the traveling distance can be easily calculated by a final unit calculation or the like even by a flag judgment by a microcomputer or the like.

The traveled distance calculated by the distance calculating means 2 is output in an updating cycle for each minimum display unit and held in the holding means 3 such as a latch circuit or a RAM. The distance data updated and held by the holding means 3 is digitally displayed on a display device such as a liquid crystal display or a fluorescent display tube via the driver 4 so that the driver can sequentially confirm the accumulated traveling distance.

The control means 6 controls the update timing of the distance calculation means 2 and the like, and also stores the latest traveling distance data in the distance calculation means 2 or the holding means 3 in the non-volatile memory 7. Nonvolatile memory 7 at this time
The distance data is stored at a plurality of memory addresses sequentially at predetermined time intervals, and the distance data for the latest predetermined time from the latest is constantly stored or updated, or the predetermined distance is stored. It can be configured to similarly store and update each time it changes, or can be configured to store the latest distance data at that time only when the ignition switch is turned off.

As shown in FIG. 2, the non-volatile memory 7 is provided with a mileage storage area 7A and a check area 7B in its memory area. The mileage storage area 7A consists of a plurality of addresses 7An and has an address number of 2 By changing the digits "00" to "99", for example, the lower 2 digits of the 6-digit distance data can be displayed by the address number.

That is, the lower two digits are used as the lower two digits of the travel distance, and each time the travel distance changes by a minimum unit, the address is changed in accordance with the increment value, and the address is stored for the first time by carrying up to the third digit. The configuration is such that a carry numerical value is updated to the data. As a result, the transition of the distance at the minimum unit level can be stored without increasing the storage capacity. In this case, since the display adopts a numerical value including the address number as the distance, a RAM as a holding means is provided in the control means 6, and the distance calculation means 2 calculates only the section distance after the ignition switch is turned on to start traveling. Then, the RAM is updated for each increment, and the nonvolatile memory 7 is sequentially added and stored, and the display data to the display 5 is output from the control means 6 as the cumulative latest distance of the nonvolatile memory 7. To do.

Here, in order to make the description easy to understand, 4
Address 7A0-7 in the example of storing the traveling distance to the digit
7 addresses of A9 → 7A1 → 7A2 →
The traveling distance is stored in the cycle of 7A9 → 7A0.

Further, the check area 7B stores four digits in each of the three addresses, in this case, 4-bit "0" and "1" data, for example, "1010" common to each bit as predetermined predetermined numerical data. Is memorized. Therefore, the latest data in the non-volatile memory 7 is preset in the distance calculation means 2 together with the ignition switch being turned on, and the distance from the cumulative initial value is counted up and the distance is displayed on the display 5 via the holding means 3. Become.

The control means 6 stores the latest distance data in the holding means 3 in the running distance storage area 7A of the nonvolatile memory 7.
The addresses 7A0 to 7A9 are stored in this order.
At the same time, the latest data in the nonvolatile memory 7, that is, the data having the maximum value, is read out and transferred to the distance calculation means 2 when the ignition switch is turned on while the vehicle is in the running state from the vehicle non-use state in which the ignition switch is turned off. Is for accumulating the traveling distance by new traveling using this data as an initial value.

At this time, if some abnormality occurs in the non-volatile memory 7 and the distance data in the traveling distance storage area 7A is defective, the check area 7B in the same non-volatile memory 7 is stochastically stochastized. Since a defect has also occurred, the numerical data of the check area 7B is read prior to the process of reading the distance data of the non-volatile memory 7, and if there is an abnormality in this numerical data, the distance data of the running distance storage area 7A is read. Also, it is determined that an abnormality has occurred, and the display unit 5 displays an abnormality. Other special display members may be used for the abnormality display in this case, but a special display may be performed in the distance display segment or a blank display may be used to notify the abnormality.

This abnormality detection functions in the same manner not only when the stored data in the non-volatile memory 7 itself is defective, but also when the data is garbled due to an interface failure such as a connection line short circuit or a read failure due to noise.

The above-mentioned method of judging an abnormality is performed by the numerical data "1010" of the check area 7B read out in advance.
Can be determined by whether or not it matches the data stored in advance. In the simplest case, a numerical value “1010” is stored separately (for example, a DIP switch), and the numerical data read out is compared with this value to obtain “0101”.
If there is a change, it can be determined that the data is defective depending on whether the stored data of the non-volatile memory 7 itself is defective or a read error due to an interface failure.

Here, three addresses 7B1 and 7B
Numerical data “0101” common to 4 bits of 2,7B3
Is stored and a majority decision is taken for each bit at the time of reading, and it is determined whether or not the numerical value consisting of the value of each bit obtained by this majority decision is a predetermined numerical value.

In comparison with the above-mentioned separate storage data, this majority decision is such that even if an error occurs in only one bit, it is a level that can be adopted as normal data instead of a large error. , It can be used in cases where it is allowed instead of displaying abnormally in all cases, but it is possible to judge by this majority decision and by the pattern of the numerical data to be stored, even if the numerical data is not stored separately. It is the one.

That is, when the numerical data pattern of "1010" is adopted, the arrangement pattern of "1" and "0" is alternating. Therefore, if the alternating pattern is not changed by the majority vote, it is normal, and it is assumed that it is changed. If it is abnormal, it is judged.

It is needless to say that the control means 6 can be constituted by a microcomputer together with other constitution means, and each function can be performed by a program.
Judgment based on the predetermined numerical data is not limited to once
When it is determined that the abnormality has occurred twice, when the same numerical data is once written in each address of the check area 7B and the read determination is performed again by the same method, when it is abnormal, it is determined that the read error is due to the interface failure. .

[0024]

As described above, according to the present invention, by storing the predetermined numerical data in the non-volatile memory as described above, and reading the numerical data prior to the reading of the actual mileage data and judging the matching thereof, It is possible to detect defective data stored in the non-volatile memory itself or defective data due to a read error due to an interface failure, prevent erroneous mileage and its display based on these erroneous data, and prevent the driver from driving erroneously. It is possible to provide an extremely reliable electronic odometer that does not display the distance.

[Brief description of drawings]

FIG. 1 is a block diagram showing a typical circuit configuration of an electronic odometer according to the present invention.

FIG. 2 is a memory area of a non-volatile memory for explaining data judgment of the present invention and a judgment explanatory view.

[Explanation of symbols]

 1 distance detection means 2 distance calculation means 3 holding means 4 driver 5 indicator 6 control means 7 non-volatile memory

Claims (2)

[Claims] 1. A distance calculating means for calculating a running distance by counting the pulse signals from a distance detecting means for outputting a pulse signal for each predetermined running distance, and a hold for updating and holding the running distance of the distance calculating means. Means, a display for displaying the calculated traveling distance, and a control means for storing the traveling distance in a non-volatile memory at a predetermined timing and outputting the stored data to the distance calculating means or the holding means. In the non-volatile memory, a travel distance storage area for storing the calculated travel distance and a check area for storing predetermined numerical data are provided in the nonvolatile memory, and the control means travels in the storage area. When the distance is output to the distance calculating means or the holding means, the numerical data of the check area is read out and stored in advance. An electronic odometer, which is characterized by determining whether or not it matches a predetermined numerical value. 2. The check area comprises a plurality of addresses each having a predetermined number of bits, and the same numerical value data is stored in each address, and the control means takes a majority decision for each common bit of each address. The electronic odometer according to claim 1, wherein it is determined whether or not the numerical value obtained by the above is numerical data stored in advance.