JPH0579379A - Control method - Google Patents

Abstract

(57) [Summary] [Object] An object of the present invention is to store a learning parameter at a time as short as possible in an EEPROM in a system having no self-shut-off function, protect the data from a phenomenon such as battery removal, and specify the learning parameter. The write operation more than the specified number of write compensation times is prohibited, and EE
It is to provide a method of using a PROM within the number of write compensation times. [Structure] The data is protected by writing a learning parameter and the number of times of writing from a backup RAM to an EEPROM at regular intervals. According to the present invention, the learning parameter can be protected from the phenomenon such as the attachment / detachment of the battery, and the trouble due to the excess of the number of writing compensation of the EEPROM can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to engine control,
It relates to a method of retaining the learned data.

[0002]

2. Description of the Related Art In a conventional device, as described in JP-A-55-138104, when a factor causing the loss of data in a RAM occurs, it is saved in an EEPROM.

[0003]

The above-mentioned prior art does not have a self-shut-off function (a function of supplying power until a certain series of operations is completed when a factor such as power supply to the system is cut off). In the system, no consideration is given to writing the maximum amount of data to another external memory by a communication method with a low transfer rate such as serial communication. Therefore, when the KEY SW is turned off, the CPU stops operating. The latest parameter learned immediately before turning off the KEY SW is set to the EEP of the serial communication system.
There is a problem that the data cannot be held in the ROM, and when the backup power supply is cut off, the data in the backup RAM becomes indefinite and the learning parameter is lost.
In addition, the EEPROM guarantees the number of writing times by the manufacturer, and there is a risk that the writing operation may be performed even if the number of times is exceeded.

An object of the present invention is to retain learning parameters even when the backup power supply is cut off, and to prohibit writing to the EEPROM more than the guaranteed number of times of writing, and further, there is no self-shut-off function. It is an object of the present invention to provide a system that performs learning control again by using a learning parameter that has been previously learned and prevents a problem due to an excess of the number of times of writing, in spite of shutting off the backup power supply.

[0005]

In order to achieve the above object, the learned parameters are written from the backup RAM to the EEPROM at regular time intervals, and the number of times of writing is counted each time to obtain the guaranteed number of times of writing. Then, the above problem is solved by controlling so that the writing operation to the EEPROM is not performed.

[0006]

[Operation] When the system is first started, the write count is decremented after a certain time (T) has passed from that point, and the learned parameter and the incremented write count are transferred from the backup RAM to the EEPROM by serial communication. A writing task (a series of program units required to complete one process) is provided. After the completion of the task, when a certain time (T) has passed again, CP
If U does not reach the guaranteed write count by monitoring the write count, the series of operations of the task is executed again. If the guaranteed write count is reached, E
The writing operation to the EPROM is prohibited.

[0007]

EXAMPLE An example of the present invention will be described below.

FIG. 1 is a block diagram of the present invention. Reference numeral 1 is an engine control device. The engine control device takes in analog or digital input signals from the respective sensors and SW into the internal two microcomputers, calculates them by the three CPUs, and controls fuel injection, ignition and the like. Meanwhile, the CPU 3 performs learning and stores the learning parameters obtained thereby in the backup RAM 4 connected by the parallel communication system as needed. The backup RAM 4 and the EEPROM 5 are connected by a serial communication method, and the learning parameters are transferred from the backup RAM to the EEPROM at regular time intervals (T).

FIG. 2 shows a microcomputer and EEPRO.
The learning parameter and the number of times of writing between M, the data and control flow of the write operation and the read operation are shown. First, the write operation will be described. As mentioned above, the microcomputer performs learning control while controlling the engine. The learned learning parameters are sent from the CPU to the backup RAM using the route 6. The CPU counts a fixed time (T) after starting and writes the count value (A) into the backup RAM using the path 8 as needed. When the counted value reaches a certain time (T), the CPU compares the number of writes in the backup RAM with the guaranteed number of writes that has been input in the ROM beforehand, and if the former is large, the EEP
Prohibit writing to ROM. If the former is a small value or the same value, the write count is incremented, writing to the backup RAM using the path 7 and writing to the EEPROM is permitted, and the path from the backup RAM to the path 9,
The learning parameter and the number of times of writing are transmitted to the EEPROM by 10 (serial communication). The CPU repeats the task of performing such a series of operations, and causes the EEPROM to store new learning parameters and the number of times of writing up to that time. Next, the reading operation will be described. KEY
When the SW is turned ON from the OFF state, the CPU first uses the path 12 in the RESET routine to perform the backup RA.
Check M data. If the check result is OK, the learning parameter of the backup RAM, the number of times of writing, and the count value (A) of the constant time (T) are used for the calculation. If the battery is removed, RA
If the value of M becomes indefinite and the check result is NG, the CPU performs EEPRO by serial communication of paths 9 and 10.
The learning parameter and the write count are read from M and used in the calculation. At this time, the count value (A) for a certain period of time (T) is cleared, and the count value restarts from 0.

[0010]

According to the present invention, the learning parameter is set to EEPR in the system without the self-shutoff function.
The problem can be caused by exceeding the number of write operations by storing in the OM and enabling learning control with new learning parameters even when the backup power supply is cut off, and by prohibiting writing to the EEPROM more than the guaranteed number of write operations. Can be prevented.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of the present invention.

FIG. 2 is a diagram showing data and a flow of control at the time of writing to and reading from an EEPROM.

FIG. 3 is a flowchart showing the operation of the present invention.

[Explanation of symbols]

1 ... Engine control device, 2 ... Microcomputer, 3
… CPU, 4… backup RAM, 5… EEPRO
M, 6 ... Movement of learning parameter in microcomputer, 7 ... Movement of write number in microcomputer, 8 ... Movement of count value for a fixed time (T), 9 ... Movement of learning parameter between microcomputer and EEPROM, 10 ... Movement of the number of times of writing between the microcomputer and the EEPROM, 11 ... Command of serial transmission / reception from CPU, 12 ... Backup RAM check operation at restart.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masami Shida Inventor Masami Shida 2520 Takaba, Takata, Ibaraki Prefecture, Hitachi Ltd. Automotive Equipment Division (72) Inventor Takashi Hasunuma 2477 Kashima Yatsu, Katsuta, Ibaraki, Japan 3 Hitachi Automotive Engineering Co., Ltd. (72) Inventor Masahiro Zaitsu 2477 Kashima Yatsu Kashima, Katsuta City, Ibaraki Prefecture 3 Hitachi Automotive Engineering Co., Ltd.

Claims (3)

[Claims] 1. A microcomputer and a backup RA
In a system for controlling fuel injection, ignition timing, etc., which is composed of M and EEPROM (ROM that allows a user to electrically erase a program), the control method is characterized in that the learned parameters are written into the EEPROM in advance. .. 2. The control method according to claim 1, wherein the backup RAM (even if the power supply to the system is cut off,
The number of times data is written to the EEPROM from the RAM that can secure data by the backup power supply is counted, and when the guaranteed number of times of writing is reached, the EEPR
A control method characterized by inhibiting writing to an OM. 3. The control method according to claim 1, wherein an EEPROM of a serial communication system (communication system in which a single signal line is used to transfer bit by bit) is used.