JPH08304103A - Electronic distance recorder - Google Patents

Abstract

PURPOSE: To prevent incorrect data from being written, and prevent indication of an incorrect running distance by comparing a holding data of a holding means with a plurality of storage data in a nonvolatile memory prior to writing the data in the nonvolatile memory. CONSTITUTION: A running distance obtained by a distance calculation means 2 is outputted in the updated cycles of every unit for minimal display and is held in a holding means 3 such as a RAM, etc. A control means 6 controls the update timing of the means 2 and allows a nonvolatile memory 7 to store the updated running distance data in the means 3. The storage timing of the distance data which is stored in the memory 7 at that time is successively stored in a plurality of memory addresses at the specified interval of time, so that the updated distance data is stored at all times. When an abnormality occurs in the means 3 and the holding updated distance data becomes defective, the means 6 detects the abnormality of the distance data prior to writing the distance data to the memory 7, and it writes a normal distance data of the memory 7 to the means 3 instead of writing it to the memory 7.

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 data destruction in a RAM (holding means) for writing and reading mileage data to and from a nonvolatile memory.

[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. In particular, even if the holding means for updating and holding the mileage, for example, the held data in the RAM is destroyed due to noise such as garbled bits, the stored data in the non-volatile memory can be read out and written in the RAM to restore the normal condition. It is being appreciated.

[0004]

In the prior art, however, the stored data in the holding means such as RAM may change bits due to some noise or the like and become defective data. Not only will the destroyed defect be stored in the non-volatile memory at the normal write timing, and the defective data will be used as an indication of the mileage, but also in the non-volatile memory in which the defective data was written. Since the data is transferred as it is to the holding means as correct data, there remains a problem that all the updates of the traveling distance thereafter become defective.

It is an object of the present invention to judge defective data destroyed by a cause such as noise in a holding means such as a RAM by normal data in a non-volatile memory and prevent the defective data from being used by mistake. To do.

[0006]

According to the present invention, there is provided a distance calculating means for counting the pulse signals from a distance detecting means for outputting a pulse signal for each predetermined traveling distance to calculate the traveling distance, and the distance calculating means. Holding means for updating and holding the running distance, a display for displaying the running distance that the holding means is struggling to hold, a non-volatile memory for sequentially storing the running distance updated and held at a predetermined timing, And a control unit for controlling the updating of the traveling distance in the holding unit and the writing process to the non-volatile memory, wherein the control unit holds the held data of the holding unit and a plurality of stored data of the non-volatile memory at a predetermined timing. When the number of coincidences between a plurality of stored data and the held data is less than or equal to a predetermined number, the holding means has a judgment function for judging the held data as defective. The features.

Further, the non-volatile memory is constituted by a distance data area consisting of a plurality of addresses, the lower two digits of the holding data in the holding means are made to correspond to an address number, and the upper digits are stored in the distance data area. It is characterized in that the stored data used for the held data defect determination in the control means is the stored data of a plurality of addresses before and after the address number corresponding to the lower two digits of the held data.

Furthermore, whether the plurality of stored data to be compared and the held data are coincident with each other is whether the stored data in the distance data area and the upper digit of the held data are completely coincident with each other or whether the stored data is smaller by the upper minimum unit. The feature is that it is executed depending on whether or not.

[0009]

The data held by the holding means such as the RAM is compared with a plurality of data stored in the non-volatile memory, and if the number of data matches does not reach the predetermined number, it is determined that the held data is defective. It is possible to prohibit the adoption display of the defective data due to garbled bits caused by.

[0010]

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 input pulse signal is input to the calculation means 2 and the input pulse signal is counted up to output unit traveling distance data for each 1 km unit, for example. In this count-up, the presence or absence of the input pulse signal is determined by the reference clock signal, and for example, 1 km is calculated with 4000 pulses based on the number of pulses. That is, the distance calculating means 2 can be achieved by a combination in the counter circuit, but the traveling distance can be easily calculated by a final unit calculation or the like even by a flag judgment by the microcomputer or the like.

The traveled distance calculated by the distance calculation means 2 is output in an update cycle for each minimum display unit and held in the holding means 3 such as a latch circuit or a RAM. Distance data (retention data) updated and retained by the retaining means 3
Is digitally displayed as a decimal 6-digit numerical value on the display 5 such as a liquid crystal display or a fluorescent display tube via the driver 4, and the driver can successively confirm the accumulated traveling distance. A signal for each minimum unit counted up by the distance calculation means 2 is input to the holding means 3 here, and added and updated as the latest accumulated traveling distance. The counting up by the distance calculating means 2 and the distance data accumulation by the holding means 3 are
In addition to signal transfer and updating for each minimum unit such as 1 km, cumulative counting up by presetting the cumulative traveling distance to the distance calculating means 2 and counting up signal output in a larger unit and calculation by addition and updating thereof Good.

The control means 6 controls the update timing of the distance calculation means 2 and the like, and stores the latest traveling distance data in the holding means 3 in the non-volatile memory 7. The storage timing of the distance data in the non-volatile memory 7 at this time is sequentially stored in a plurality of memory addresses at a predetermined time interval, and the distance data for the latest to past predetermined time is constantly updated and stored. Alternatively, the memory may be updated in the same manner each time the predetermined traveling distance changes.

Here, the nonvolatile memory 7 such as the EEPROM is provided with a distance data area composed of a plurality of addresses as shown in FIG. 2, and the address number of each area is set to two digits "00" to "99". Thus, for example, the lower two digits of the 6-digit distance data are displayed with the address number.

That is, the lower two digits are set as the lower two digits of the traveling distance, and each time the traveling distance changes by a minimum unit, the address is changed in accordance with the increment value, and the storage in the address is not started until the third digit is carried up. 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, the RAM serving as the holding unit 3
The latest storage data of the non-volatile memory 7 is written together with its address number when the ignition switch for running start is turned on, and the distance is added by subsequent running and the non-volatile memory 7 is sequentially added and stored by updating the address number. The accumulated latest distance in the holding means 3 is displayed at.

Here, in order to make the explanation easy to understand, 6
Digit mileage is 10 for each address number and stored data
Displayed in radix and 1 from "00" to "99"
The 00 area, that is, the 2-digit display up to 100 km is replaced with the address number. This corresponds to the address number in the minimum display unit.
If the memory may be roughly stored, for example, it may be configured to store 50 areas from "00" to "49" in units of 2 km. In this case, the distance of the lower two digits is This means that an even distance that is a multiple of the address number is stored. Therefore, 100 → 100 → 00 → 01 → 02 → ...
The traveling distance is stored in the cycle of 99 → 00 (data in the distance data area is updated by incrementing the minimum unit).

When the cumulative distance traveled is counted up by the distance calculation means 2, 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 counting up from the cumulative initial value is performed. The distance is displayed on the display device 5 via the holding means 3.
Will be displayed at.

The control means 6 stores the latest distance data in the holding means 3 in the running distance data area of the non-volatile memory 7 in the order of the addresses 00 to 99. 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 holding means 3 when the ignition switch is turned on, which is performed while the vehicle is in the traveling state from the vehicle non-use state of the ignition switch off. This data is used as an initial value to accumulate the traveling distance by new traveling.

At this time, if some abnormality occurs in the holding means 3 and the distance data being updated and held becomes defective, the judgment processing performed prior to the distance data writing processing to the non-volatile memory 7 is performed. The control means 6 executes a process of determining the abnormality of the distance data, presetting (writing) the normal distance data of the non-volatile memory 7 to the holding means 3 without writing to the non-volatile memory 7.

The determination process in the control means 6 at this time is performed by comparing with the stored data corresponding to the data held in the holding means 3 in the nonvolatile memory 7 shown in FIG. Whether to use the data is read by comparing a plurality of stored data of addresses before and after including the address number corresponding to the lower two digits of the held data.

That is, the latest stored data (previous write data) in the nonvolatile memory 7 is the address 55.
Then, the next update data should be "123456" in the holding means 3, and if this remains normal, "1234" is stored in the data area of the address 56 corresponding to the lower two digits "56". "(Up to that time, old" 1233 ") will be written, but prior to this writing process, for example, data for 5 addresses of the upper address including the address 55 and data for 5 lower addresses from the address 56. Is read out and the coincidence comparison with the upper digit "1234" of the data in the holding means 3 is sequentially performed.

At this time, the judgment is made by the stored data "1234" which completely matches the upper digit of the held data or 1 from the stored data.
When there are not two or more small storage data "1233" in the data of all 10 addresses, it is determined that the held data is abnormal and writing to the address 56 of the nonvolatile memory 7 is not performed. The stored data of the address 55, which is the latest data, is written in the holding means 3 as the 6-digit distance data including the address number.

In this case, the upper digit of the retained data is "123".
Since “4” is correct, the number of matches with the compared address data is two or more, and it is determined that the held data is correct, and “1234” is written to the address 56. The reason that the number of coincidences is two or more is that at least accurate comparison is made by comparison with the common data value of the non-volatile memory 7, and the number of target addresses to be compared can be any plural number. And set it.

Therefore, if the upper digit of the data held in the holding means 3 is garbled to, for example, "1334", the address 5
Since the data of a plurality of addresses before and after 6 do not match in "1234" and "1233" (matching when perfect matching and 1 less data), the control unit 6 determines the held data as defective, and the nonvolatile The correct distance data of the property memory 7 is written in the holding means 3, and the correct distance can be maintained by the display and writing by the subsequent update.

When the data held in the holding means 3 is abnormal in the lower two digits instead of the upper digit, the comparison target address in the non-volatile memory 7 deviates from the latest address.
Since it is sufficient to make an error only in the lower digit (the smallest unit of the lower 3 digits at most), a correct error can be displayed without causing a large error as the accumulated traveling distance.

In the above embodiment, the storage format of the non-volatile memory 7 corresponds to the lower two digits of the address number and is also used for selecting the comparison target address.
Even in the case of simply storing 6 digits sequentially in the data area, since the previous write address and the next write address are clear in the control process, the comparison with the held data of the holding means 3 is performed. The same defect determination can be performed by determining a plurality of addresses based on the address information and the number of coincidences.

[0026]

As described above, the present invention compares the data held in the holding means such as RAM with a plurality of data stored in the non-volatile memory prior to writing the data in the non-volatile memory, for example, and matches the held data. When the stored data is less than the specified number, it is judged that the stored data is defective and writing to the non-volatile memory is not performed. Therefore, the cumulative data of the traveled distance based on incorrect data is destroyed (writing of defective data) and its display. Therefore, it is possible to provide an electronic odometer which is highly reliable and which prevents the driver from displaying an incorrect mileage.

[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 data area address of a non-volatile memory for explaining data determination of the present invention and an explanatory diagram of determination.

[Explanation of symbols]

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

Claims (3)

[Claims] 1. A distance calculating means for calculating the traveling distance by counting the pulse signals from a distance detecting means for outputting a pulse signal for every predetermined traveling distance, and a holding for updating and retaining the traveling distance of the distance calculating means. Means, a display for displaying the traveled distance that the holding means is struggling to hold, a non-volatile memory for sequentially storing the updated and held traveled distance at a predetermined timing, and an update of the traveled distance in the holding means. Control means for controlling writing processing to the non-volatile memory, the control means compares the held data of the holding means with a plurality of stored data of the non-volatile memory at a predetermined timing to obtain a plurality of stored data. An electronic odometer having a determination function of determining that the data held by the holding means is defective when the number of matches between the holding data and the holding data is equal to or less than a predetermined number. 2. The non-volatile memory is composed of a distance data area consisting of a plurality of addresses, the lower two digits of the holding data in the holding means are made to correspond to an address number, and the upper digits are stored in the distance data area. 2. The electronic odometer according to claim 1, wherein the storage data used by the control means for determining whether or not the retention data is defective is storage data of a plurality of addresses before and after the address number corresponding to the lower two digits of the retention data. 3. Whether the plurality of stored data to be compared and the held data are coincident with each other is the stored data in the distance data area and the upper digit of the held data are completely coincident with each other, or whether the stored data is smaller by the upper minimum unit. The electronic odometer according to claim 2, wherein the electronic odometer is executed depending on whether or not.