JPH11141391A - Controller for automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To write data in a nonvolatile memory only when there are difference in both data and prohibit the writing of unnecessary data in the volatile memory by comparing the data in a volatile memory with the data in the nonvolatile memory, when a key switch is turned off. SOLUTION: An electronic control unit (ECU) 5 is provided with an input interface part 11, a nonvolatile memory (EEPROM) 17 which is nonvolatile and can electrically read and write, a volatile and read-write memory (RAM) 18, a nonvolatile and read-only memory (ROM) 19, etc. When data is transmitted to RAM 18, a microcomputer calculates the sum value of all the transmitted data, this value and a sum value stored in a prescribed address of the EEPROM 17 are compared with each other and, if the both values do not coincide with each other, it is regarded that the data stored in the EEPROM 17 is broken and the value is not used for the control.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control apparatus for a vehicle having a function of storing a control amount for controlling a vehicle and a function of storing a self-diagnosis result.

[0002]

2. Description of the Related Art Conventionally, a volatile memory and a non-volatile memory have been used for an automobile control device, and after starting an engine, learning information and the like have been transferred from the non-volatile memory to the volatile memory, and this value has been self-corrected. After that, there is a method of reducing the number of times of writing to the nonvolatile memory by returning to the nonvolatile memory. For example, Japanese Patent Application Laid-Open No. Sho 61-171864 proposes this. In addition, JP-A-5
Japanese Patent Application No. 289949 proposes that writing to a nonvolatile memory when data is updated is limited to a time when a key switch is turned on.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the 1864 publication, the transfer of data between the volatile memory and the nonvolatile memory is described, but the nonvolatile memory generally has an upper limit on the number of times of writing, and when the writing operation is performed more than a predetermined number of times. Has a problem that data reliability cannot be obtained. For example, if the ignition key is repeatedly turned on and off in a very short period of time, the contents of the volatile memory and the contents of the non-volatile memory are completely the same, even though the contents of the non-volatile memory are completely the same. Writing is performed, and an unnecessary writing operation is performed.

On the other hand, in the above-mentioned Japanese Patent Application Laid-Open No. 5-289949, data in a nonvolatile memory and data in a volatile memory are sequentially compared while a key switch is turned on. Has been proposed, but if the target data is several hundred bytes or more, it is checked within a predetermined period (for example, within a 10 ms period) whether or not the data has been rewritten. It is difficult.

An object of the present invention is to provide an automobile control device which inhibits unnecessary data writing to a nonvolatile memory in view of the above-mentioned problems. Also, instead of checking for data updates one by one,
Immediately after the switch is turned off, by using the sum values obtained by multiple arithmetic methods collectively, it is possible to reliably verify whether data has been updated and to store the latest data in the nonvolatile memory. The purpose is to provide a device that can be left behind.

[0006]

The above object is achieved by comparing both the data in the volatile memory and the previously stored data in the nonvolatile memory when the key switch is turned off. Is done.

As a means for quickly and surely verifying whether or not data has been updated, calculation of a sum value using at least two or more different arithmetic expressions for both data in a nonvolatile memory and data in a volatile memory. And verify equivalence.

[0008] The elapsed time from when the ignition key switch is turned on is measured to detect frequent key switch on / off.

That is, when the key switch is turned off, the data in the volatile memory to be written from now on is compared with the contents of the data in the nonvolatile memory stored previously. As a result, data is written only when there is a difference between the data, and is not written when there is no difference between the data.

As a means for reliably verifying whether or not the data has been updated as described above, when a key switch is turned on, a simple addition value of all target data stored in a nonvolatile memory and The exclusive OR is stored at a predetermined address in the volatile memory. Key·
When the switch is turned off, a simple logical sum and an exclusive logical sum are calculated for all target data in the volatile memory to be written. As a result, the value stored at the time of key-on is compared with the value calculated from the volatile memory data calculated this time. Does not write to the non-volatile memory, but if either one does not match, writes the data on the volatile memory to the non-volatile memory. As a method for evaluating data equivalence, an arithmetic method other than the above, such as a logical product, which is useful for verifying update of data may be used.

When the key switch is turned off when the elapsed time since the ignition key switch is turned on is equal to or less than a predetermined value, writing of data to the nonvolatile memory is prohibited by frequently prohibiting writing. Unnecessary writing due to the on / off operation of the key switch can be prevented.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 shows an overall configuration of an apparatus according to an embodiment of the present invention. Reference numeral 1 denotes a rotation sensor for detecting the number of rotations of the engine. Reference numeral 2 denotes a water temperature sensor for detecting the temperature of cooling water for cooling the engine. Reference numeral 3 denotes a throttle sensor for detecting the amount of depression of the accelerator pedal. Reference numeral 4 denotes a serial communication line for exchanging information with another external control device. 5 is an electronic control unit (hereinafter referred to as E
CU), and detects the operating state of the engine on the basis of the above information 1-4, and controls the actuator 6.

The ECU 5 has a self-diagnosis function for detecting the input sensor signal and abnormality of the actuator. When an abnormality is detected, the ECU 5 stores the failure information therein and turns on the diagnosis warning light 7. Reference numeral 8 denotes a battery serving as a power supply for the ECU 6, and the power supply to the ECU 5 is continued for a predetermined time even when the ignition key switch is turned off.

The energization may be interrupted by the function of a self-destruct circuit incorporated in the ECU itself, or the supply may be interrupted outside the ECU. FIG. 1 shows an example of a system that is shut off by a self-destructing circuit of an ECU.
It should be noted that the ignition key information may be transmitted directly from the outside by a switch signal, but FIG. 1 shows an example of a system transmitted from another control device through a serial communication line. FIG. 2 shows an internal configuration of the ECU 5. The ECU 5 includes an input interface unit 11 that processes various sensors and switch information.
, A serial communication interface 12, an A / D converter 13 for converting an analog signal output from the input interface 11 into a digital signal, a microcomputer 14 for calculating various input signals, and an ignition transmitted through the communication interface 12 described above. A self-destruction circuit 15 for shutting off the power supplied to the microcomputer 14 based on the key information; an output interface 16 for outputting signals for controlling various actuators connected to the outside; , A writable nonvolatile memory 17 (hereinafter referred to as EEPROM), a volatile readable / writable memory 18 (hereinafter referred to as RAM), and a nonvolatile read-only memory 19 (hereinafter referred to as ROM).

The microcomputer 14, the RAM 18, and the ROM 19 are connected via an address bus 20 and a data bus 21, and various kinds of information are exchanged on this bus line. Note that the EEPROM 17 and the microcomputer 14 exchange information via the serial communication line 22 instead of the bus line. Note that a flash memory instead of an EEPROM may be used as the nonvolatile memory.

FIG. 3 shows the timing of data exchange between the RAM 18 and the EEPROM 17 when the ignition key switch is turned on and off. When the ignition key switch is turned on, data (for example, learning values and failure diagnosis information) stored in the EEPROM 17 is transferred to the RAM 18.
On the other hand, when the key switch is turned off, the RAM 1
The data stored in EEPROM 8 and used for control is stored in EEPROM 17
Is stored in At this time, it is assumed that a sum value obtained by summing all the stored data is stored at a predetermined address of the same EEPROM 17.

This sum value is used when data is transferred from the EEPROM 17 to the RAM 18 at the next key switch-on.
Used to verify that the transferred data is correct. That is, when the data is transferred to the RAM 18, the microcomputer calculates the total value of all the transferred data, and compares the calculated value with the sum value stored at a predetermined address of the EEPROM 17, If the values do not match, it is assumed that the data stored in the EEPROM 18 has been destroyed, and that value is not used for control.

In this case, a default value provided in advance is used for control. By the way, the transferred data is generally a learning value indicating the state of the engine and the result of self-diagnosis (such as an error code).
It is stored at a predetermined address on the OM18.

Next, the technique described in claim 1 will be described with reference to FIG. The flowchart shown in FIG. 4 is a routine executed every 10 ms. This process is executed after the key switch is turned off and normal engine control and transmission control are completed. Therefore, the processing is performed in a state where the load on the microcomputer itself is reduced.

First, in steps 100 to 102, it is determined whether or not the ignition key switch is turned off and a mode for performing self-destruction processing is entered. The trigger to enter the self-destruction process is the key switch off determination shown in process 101, whereby the self-shut-off flag shown in process 102 is set. When the self-shutoff flag is set, the process 103 is executed. That is, the data on the EEPROM 17 and the corresponding RA
The equivalence with the data on M18 is checked.

In process 104, the data is determined to be equal, and if it is determined that the two data are different, it is determined that the data has been updated, and the data in the RAM 18 is overwritten in the EEPROM 17. Is performed 105.

In the process 106, the number of data to be written is checked, and the processes 103 to 10 are performed a predetermined number of times.
Step 6 is repeated. If it is determined in step 104 that the data matches, the process of writing to the EEPROM 17 is not performed, and the process ends. By the above processing, the writing processing to the EEPROM 17 is executed only for the updated data after the key switch is turned off.

Next, the matter described in claim 2 will be described. FIG. 5 is an image of the data configuration. The map 200 shows the structure of data on the RAM 18. The map 201 shows the structure of data on the EEPROM 17. When the ignition key switch is turned on, the data 1 to n stored in the EEPROM 17 are
All are transferred to the RAM 18. At that time, SUM X
The value of SUM Y is also transferred to the RAM 18.

SUM X is a sum value calculated when the contents of the RAM 18 were stored in the EEPROM 17 the last time the key switch was turned off, and the lower 1 byte of the result obtained by simply summing the values of data 1 to n Is the value of SUM Y
Is the sum value calculated at the same timing, but this is the lower 1 byte of the result obtained by calculating exclusive OR of data 1 to n. These sum values are used to verify whether the data on the RAM 18 has been updated the next time the key switch is turned off.

The reason for providing two kinds of sum values in this way is that it is not reliable to verify the equivalence of data with only a commonly used simple sum value (here, SUM X). For example, if there is a +1 bit change in data 1 and a -1 bit change in data 2, the value of the simple sum does not change even though the data has been updated. This is because the judgment is made as if there was no update. Therefore, if the sum value SUMY by exclusive OR is used in combination with this, it is possible to surely determine whether or not data has been updated.

FIG. 6 is a timing chart showing a data transfer process when the ignition key switch is turned on and off. FIG. 7 is a flowchart showing details of the processing when the key switch is turned off. In the process 300, SUM X1 and SUM Y1 are calculated based on the data 1 to n on the RAM 18. The values of SUM X1 and SUM Y1 are calculated by a method similar to the equation shown in FIG.

In steps 301 and 302, the values of SUM X1 and SUM Y1 are compared with the values of SUM X and SUM Y. As a result, SUM X = SUM X1 and S
If it is determined that UMY = SUM Y1, it is determined that the data in the RAM 18 has not been updated since the last time the key switch was turned on, and no data is written to the EEPROM 17.

On the other hand, if it is determined in steps 302 and 303 that the data has been updated,
18 is written to the EEPROM 17 and the calculated SUM X1 and SUM Y1 are replaced with the new sum value S.
Store them in the EEPROM 17 as UM X, SUM Y. This makes it possible to determine at a high speed whether or not data has been updated, and to permit writing to the EEPROM 17 only when data has been updated.

Next, the matter described in claim 3 will be described. FIG. 8 is a flowchart showing the processing. This flow is processed after the ignition key switch is turned off. First, process 400
Then, it is checked whether or not a predetermined period has elapsed since the ignition key switch was turned on, in this case, one second in the example.

If one second or more has elapsed, it is considered that the operation is started by normal key operation. However, if the key switch is turned off without elapse of one second, frequent key operations are performed.
It is determined that the operation is an on / off operation, and the process of transferring data from the RAM 18 to the EEPROM 17 is prohibited (process 401).

[0031]

According to the present invention, data writing to the nonvolatile memory is permitted only when a normal key operation is performed and when data is updated. The number of times of writing can be reduced, and the reliability of write data can be ensured.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of a vehicle control device according to an embodiment of the present invention.

FIG. 2 is a diagram showing an internal configuration of an ECU shown in FIG.

FIG. 3 is a timing chart showing the timing of data transfer when an ignition key switch is turned on and off.

FIG. 4 is a flowchart illustrating processing steps.

5 is a diagram showing an image diagram of data on a RAM and an EEPROM of FIG. 1 and a method of calculating a sum value.

FIG. 6 is a timing chart illustrating the processing of claim 2;

FIG. 7 is a flowchart illustrating a process according to claim 2;

FIG. 8 is a flowchart for explaining the third embodiment.

[Explanation of symbols]

5: ECU (control device), 14: microcomputer, 15: power supply self-destructing circuit, 17: EEPROM, 18: RAM, 19: ROM.

Claims (3)

[Claims] 1. A microcomputer for controlling an automobile, a rewritable volatile memory, a rewritable nonvolatile memory, and a circuit for maintaining power supply to the microcomputer for a predetermined period even when an ignition key is turned off. When the ignition key switch is turned on, the operating state (learning value) of the vehicle and self-diagnosis information are stored in the volatile memory,
Immediately after the key switch is turned off, when the key switch is turned off in a device having a mechanism for storing the value stored in the volatile memory in the nonvolatile memory, An automotive control device comprising comparing the contents of a memory with the contents of the non-volatile memory, and writing data to the non-volatile memory only when there is a difference between the two data. 2. The method according to claim 1, wherein the verification of the equivalence of the data includes at least two or more operations such as calculating a sum value by an exclusive OR operation in addition to calculating a sum value by a simple summation of the target data. A control device for a vehicle, characterized by verifying data equivalence between a volatile memory and a nonvolatile memory by using a result. 3. When the ignition key switch has been turned on and not turned on for a predetermined period of time,
A control device for a vehicle, wherein when a key is turned off, storage of data in a nonvolatile memory is prohibited.