JPH0240507A - Electronic odometer - Google Patents

Abstract

PURPOSE:To retrieve the stored place of the up-to-date data simply and accurately by storing the data having a bit alignment that is different from a bit alignment of data used for expressing running distance data at a data storing place. CONSTITUTION:Data comprising the same bit alignment are written in the bytes of a specified data storing place. The bit alignment of said data is made to be an alignment that is different from a bit alignment used for expressing running distance data. In reading, a data storing place having bytes wherein said specified bit alignment is stored is retrieved. When the specified number of the bytes agreeing the specified bit alignment are present in the bytes of the stored place, data corresponding to a specified running distance are added to the data which are stored before the stored data. Thus the newest total running distance data are obtained. The data in the data storing place having the specified bit alignment are updated with said up-to-date total running distance data. A data storing place which will be updated at the next time from said updated data storing place is made to be a specified data storing place.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electronic odometer mounted on a vehicle that electrically stores the total distance traveled.

[Conventional example]

Conventionally, this type of device has been used for devices such as EEROM, which stores the vehicle's total mileage data in a non-volatile manner, in order to reliably store the data even when the battery is replaced or the bank-up voltage drops. Many things have been proposed. However, these non-volatile memories have a limit on the number of times they can be written to, and an electronic odometer that can store data while reducing this number of times is desired.
For example, as described in Japanese Patent Application Laid-Open No. 196414/1984, a method has been published that attempts to reduce the number of rewrites that one data storage area has to bear by sequentially writing total mileage data to multiple data storage areas. It becomes.

[Problem to be solved by the invention]

In this way, in a nonvolatile memory that uses a method to sequentially rewrite data to multiple data storage locations, the data storage location in which the most recently rewritten data is stored is stored in each data storage location. For example, as in the above-mentioned publication, the data storage location where the maximum value is stored may be used as the desired data storage location, or
For example, a data storage location where there is a difference in the data stored in adjacent data storage locations is selected as the desired data storage location.

In order to accurately search for this desired data storage location, the data stored in each data storage location must be reliable, but noise that occurs during data writing and failure of the data storage location are important. In rare cases where data cannot be stored accurately, programs are added to the program to deal with this problem, but as the programs become more complex, the processing time tends to increase as well.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention has provided that each byte of the desired data storage location has a bit array of data used to represent mileage data so that the desired data storage location can be accurately retrieved. is characterized by storing data with different specific bit arrangements.

〔Example〕

FIG. 1, FIG. 2, and FIG. 3 are block diagrams of the present invention, and flow charts and state diagrams showing the operation of the block diagrams will be described.

1 is a pulse generator that outputs a pulse signal every time the vehicle travels a certain distance. Reference numeral 2 denotes an arithmetic circuit having a counting function for counting pulse signals output from the pulse generator 1. Reference numeral 3 denotes a non-volatile memory for storing vehicle mileage data in BCD code. This non-volatile memory 3 has a plurality of data storage locations 3a, and each data storage location is composed of a plurality of bytes 3b. It is something.

In this embodiment, there are 50 data storage locations from address O to address 49, each consisting of 4 bytes. 4 is a write circuit, which writes the data processed by the arithmetic circuit 2 into the nonvolatile memory 3 according to the command from the arithmetic circuit 2; This is for reading out from the nonvolatile memory 3. A display device 6 is capable of displaying and temporarily storing data corresponding to the total distance traveled by the vehicle processed by the arithmetic circuit 2.

Next, the operation will be explained with reference to FIGS. 2 and 3.

In each data storage location 3a of the nonvolatile memory 3 used in this embodiment, as shown in FIG. 3a, the smaller the address, the smaller the data is stored every 1 km. The reason why the data is arranged every 1km is that when the pulse generator 1 outputs a pulse signal corresponding to the vehicle traveling route Al 11 to the arithmetic circuit 2, the address of the data storage location 3a of the non-volatile memory 3 is changed. This is because it is being updated while

In FIG. 2a, when the arithmetic circuit 2 counts pulse signals corresponding to l km, the arithmetic circuit 2 asks the readout circuit 5 which data storage location 3a of the nonvolatile memory 3 has the most recently updated data. Perform the operation to search.

The search operation is performed in FIG.
Bit array “1111” representing “1” (hereinafter referred to as F)
This is an operation to search whether or not " is stored (FIG. 3b). In this example, the data storage locations 3a at addresses 34 and 37 are searched.

In FIG. 2C, as shown in FIG. 3C, byte 3 stores F in the data storage location 3a that has already been retrieved
This is for searching how many b there are. And data storage location 3 where there are two or more bytes 3b storing F.
Let a be the latest data storage location 3a'. In this example 3
The data storage location 3a at address 4 is a pie) 3b that stores three Fs, while the data storage location 3 at address 37
a? ! Since there is only one, the one at address 34, which satisfies the condition of two or more, is the latest data storage location 3a'.

(The data at address 37 was found to be incorrect, so it will be corrected using the prescribed operation.) In some cases, there may be multiple data storage locations 3a that store the same number of data from F. Since data is updated in ascending order of address, the data storage location 3, a with the largest address is assumed to be the latest one. There are various processing methods for each case, but their explanation will be omitted as it is off topic.

In FIG. 2d, as shown in FIG.
Data in data storage location 3a before the address! 033, l
Add the data corresponding to km, and this data 1034'
is updated in the data storage location 3a at address 34 by the write circuit 4, and F is updated in the data storage location 3a at address 35.
The data is updated using FFF (Fig. 3d).

Next, we will discuss the meaning of performing step c in the flowchart of Figure 2.

The data stored in this non-volatile memory is a BCD code representing the numbers 0 to 9, ranging from "oooo" to 100.
1" is used, and the array "1111" representing F is not used for data representing mileage.

Taking advantage of this fact, in flowchart d, data FFFF is stored in the data storage location 3a' where the data has been updated most recently. This is because noise occurs when writing this data FFFF, and one of the F that should be stored in the four bytes is data other than F, for example, 1 bit becomes an error and changes from "1111" of F to "0111" of 7. Even if it changes to data, the remaining bytes represent F, and therefore, the data storage location 3a that has many bytes storing F can be said to be the data storage location where the data has been updated most recently.

Therefore, in the flowchart, the data storage location 3a that stores F as data is first searched, and then the flowchart C
By checking whether the data storage location 3a searched for is incorrect, it is possible to obtain the most accurate and latest data storage location 3a.

According to the flow from a to d above, the arithmetic circuit 2 repeats the flowchart of Fig. 2 every time a pulse signal corresponding to lkm is input, but due to an unexpected accident in the electrical system, the displayed value W6
If the backup for storing the data expires, it will no longer be displayed or stored. Therefore, when the electrical system becomes normal, the arithmetic circuit 2 first searches for the data storage location 3a' whose data has been updated most recently as shown in FIG. The data obtained by adding 1 km to the data of the data storage location 3a one address before the latest data storage location 3a' determined from FIG. d is displayed and stored on the display device 6 as the vehicle's total mileage data. Therefore, the display device 6 can always display accurate vehicle total mileage data.

From the above, the effect of the present invention is that the data storage location 3a where the latest data is stored can be accurately searched by a simple operation, and the operation is simply performed by simply
It is sufficient to search for the data storage location 3a that has 3b. In addition, even if F cannot be updated to all pies (3b) due to noise or a failure of the non-volatile memory 3, it will not have much of a negative impact on the search operation, and even if some erroneous data is written, the search operation can be performed accurately. It can be carried out.

Although data F is used in this embodiment, the present invention is not limited to this, and the same effect can be achieved by using data consisting of a bit array that is not used for data representing travel distance.

〔Effect of the invention〕

The present invention stores data that has the same bit array in each byte of the data storage location where the data has been updated, but has a specific array that is different from the bisotho array used to represent mileage data. By doing so, the data storage location where the latest data is stored can be easily and accurately searched.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the present invention, FIG. 2 is a flowchart showing the operation sequence of FIG. 1, and FIG. 3 is a state diagram showing a specific example of the explanation of FIG. 2. 2-Arithmetic circuit 3--Nonvolatile memory 3a
-Data storage location 3b-Byte 4-Write circuit 5-Read circuit

Claims (1)

[Claims] (1) an arithmetic circuit that processes data corresponding to the mileage of the vehicle; at least one nonvolatile memory having a plurality of data storage locations each consisting of a plurality of bytes; In an electronic odometer equipped with a write circuit that writes output data to a predetermined data storage location and a read circuit that reads data from the data storage location designated by the processing circuit to the processing circuit, when writing data, the predetermined Data consisting of the same bit arrangement is written to each byte of the data storage location, and furthermore, the bit arrangement of this data is data with a specific arrangement different from the bit arrangement used to represent the mileage data. and, when reading, searches for a data storage location that has a byte storing this particular bit arrangement, and among each byte in this data storage location there is a predetermined number of bytes that match said particular bit arrangement. When,
The data corresponding to the predetermined mileage is added to the data stored before the data stored in this data storage location to obtain the latest total mileage data, and this data is used to store data having the specific bit arrangement. 1. An electronic odometer, characterized in that the data at the location is updated, and the data storage location where data is scheduled to be updated next after the updated data storage location is set as the predetermined data storage location.