JP2002334023A - Electronic controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately rewrite data into a nonvolatile memory without any hindrance to normal control. SOLUTION: A battery 21 is connected to an ECU 10 through an IG switch 22 and when the IG switch 22 is turned on, the ECU 10 is supplied with electric power. The ECU 10 is equipped with a power circuit 11, a CPU 12, a RAM 13, a flash ROM 14, an EEPROM 15, and an input/output port 16. The flash ROM 14 stores various control programs and data. The CPU 12 judges whether data need to be rewritten to the flash ROM 14 when the IG switch 22 is turned on and writes the same data as the data written in the flash ROM 14 to the flash ROM 14 again when the data need to be rewritten. After the rewriting, normal engine control is started.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic control device having an electrically rewritable nonvolatile memory,
The present invention relates to an improved technique for writing the same data as the data written in the non-volatile memory to the non-volatile memory again, that is, for rewriting data in the non-volatile memory.

[0002]

2. Description of the Related Art In recent years, as an electronic control unit for a vehicle, an engine ECU having an electrically rewritable nonvolatile memory such as a flash ROM has been used.
In U, in order to deal with garbled data in flash ROM,
It is being studied to rewrite the data in the flash ROM. In other words, the data guarantee of the flash ROM is about 20 years, but rewriting is considered to be an effective means to hold data accurately.

[0003] As a conventional example, Japanese Patent Application Laid-Open No. H8-15339 has been proposed.
There is a data rewrite control device disclosed in Japanese Patent Application Laid-Open No. 7-107. In the device disclosed in the publication, when the vehicle-mounted battery is replaced, when the vehicle speed is equal to or higher than a predetermined value and the engine speed is equal to or higher than the predetermined value after the battery replacement, the write data in the EEPROM is read, and the read data is read. EEPRO
M was rewritten. In other words, during normal engine control where there is no possibility of battery shutdown, data rewriting is reliably performed.

[0004]

The data rewriting control device disclosed in the above-mentioned publication discloses an EEPR for storing a vehicle number, a destination data and other data which are sequentially updated.
It can be used for OM, but not for flash ROM used as program memory. because,
When rewriting the flash ROM, the flash R
OM data is collectively erased over a wide area. For this reason, if data is rewritten while maintaining normal engine control, the engine control and the like will be affected.

[0005] In addition to the above-mentioned prior art, a method of calculating the checksum of the data in the flash ROM during engine control to confirm the validity of the data, and performing a fail-safe process when an abnormality occurs can be considered. However, in that case, the memory data cannot be restored even if the fail-safe processing can be performed. Therefore, EC
As U, high reliability cannot be secured.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide an electronic control system capable of properly rewriting data in a non-volatile memory without affecting normal control. It is to provide a device.

[0007]

The electronic control unit of the present invention is provided with an electrically rewritable non-volatile memory, and the non-volatile memory holds various control programs. In addition, power is supplied to the electronic control device via a power switch. According to the first aspect of the present invention, when the power switch is turned on, it is determined whether or not the data in the nonvolatile memory needs to be rewritten. If the data needs to be rewritten, the data written in the nonvolatile memory is determined. The same data as described above is written into the non-volatile memory again. After the rewriting, the normal control is started. According to the present invention, the data rewriting of the nonvolatile memory is limited to the ON operation of the power switch, and the normal control is started after the writing is completed. It can be implemented properly.

According to the second aspect of the present invention, it is determined whether or not data rewriting of the nonvolatile memory is necessary at the time of the power supply delay processing, and if rewriting is necessary, the same as the data written in the nonvolatile memory is determined. Writing data to the non-volatile memory again is performed. After the rewriting, the power supply to the electronic control unit is cut off. According to the present invention, by limiting the data rewriting of the nonvolatile memory at the time of the power supply delay processing, the data rewriting of the nonvolatile memory can be appropriately performed without hindering the normal control as in the first aspect. it can.

More specifically, as described in claim 3, when it is determined that rewriting is necessary, the data of the nonvolatile memory to be written is temporarily stored in the RAM, and thereafter, the temporarily stored data is stored. May be written in the nonvolatile memory.

According to the third aspect of the present invention, as described in the fourth aspect, the nonvolatile memory is composed of a plurality of storage areas, and when it is determined that rewriting is necessary, rewriting is performed for each individual storage area. It is good to carry out. In this case, there is an advantage that a RAM area required as a temporary storage area can be small.

As a criterion for rewriting data, it is preferable to count the number of times the power switch is turned on or off and determine whether data rewriting is necessary based on the count value. . in this case,
If a predetermined count value is set as the data rewriting timing, the data can be rewritten at a desired timing.

In the invention described in claim 6, following the rewriting of the data in the nonvolatile memory, the data is inspected, and the control is shifted to the normal control on condition that the inspection result is normal. In this case, erroneous writing of data is checked, and the reliability of memory data after rewriting is improved.

According to the present invention, of the various data held in the non-volatile memory, only the data of high importance is to be rewritten. In this case, since the data rewriting is selectively performed according to the importance, the time required for the data rewriting can be reduced.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in an electronic control unit for a vehicle-mounted diesel engine will be described below with reference to the drawings.

FIG. 1 shows the configuration of an electronic control unit (hereinafter referred to as an ECU) 10 and its peripheral devices. The ECU 10 shown in FIG. 1 is configured as an engine ECU for controlling the operation state of the diesel engine, and controls the fuel injection amount and the fuel injection timing optimally. FIG.
In the ECU 10, the battery 2 is connected to an ECU 10 via an ignition switch (hereinafter referred to as an IG switch) 22.
1 is connected, and power is supplied to the ECU 10 when the IG switch 22 is turned on in response to a driver's starting operation of the vehicle.

The ECU 10 is configured as a well-known logical operation circuit, and includes a power supply circuit 11, a CPU 12, a RAM 13, a flash ROM 14, an EEPROM 15, and an input / output port 16. When the IG switch 22 is turned on, the power supply circuit 11 outputs a predetermined constant voltage V from the input voltage from the battery 21.
DD (for example, 5 volts), and the constant voltage VDD
Are supplied to the CPU 12, the RAM 13, the flash ROM 14, and the EEPROM 15, respectively. Flash RO
Each of the M14 and the EEPROM 15 is a nonvolatile memory capable of electrically writing and erasing data.

The flash ROM 14 is a relatively large-capacity (for example, 512 kilobytes) program memory for storing various control programs and data.
The flash ROM 14 is divided into a plurality of blocks (storage areas), and data is erased for each block. Each block size is, for example, 16 kilobytes. On the other hand, the EEPROM 15 is a data memory having a relatively small capacity (for example, 256 bytes), and includes data to be rewritten during operation, data unique to each vehicle (vehicle number), and data relating to the destination of the vehicle (destination). Location data).

The vehicle-mounted device 23 is electrically connected to the ECU 10. The on-vehicle device 23 includes various sensors,
It comprises a fuel injection amount control actuator, a fuel injection timing control actuator, and the like. The various sensors include a sensor for detecting an engine operation state including an engine speed sensor and a vehicle speed sensor.

Next, the operation of rewriting data in the flash ROM 14 in the ECU 10 will be described. FIG.
Is a flowchart showing a data rewriting procedure performed by the CPU 12, and this routine is started when the IG switch 22 is turned on.

When FIG. 2 is started, first, in step 1
In 01, the number of times the IG switch 22 is turned on is counted. In the following step 102, the count value (the number of times the IG is turned on) in step 101 is stored in the EEPROM 15.

Thereafter, in step 103, the current flash ROM 14 is set based on the count value of the number of times the IG is turned on.
It is determined whether or not it is the rewrite timing. That is, the number of times the IG is turned on is a predetermined value (100 in the present embodiment).
0), it is determined that it is not the rewrite timing if the predetermined value is not reached, and it is determined that the rewrite timing is reached if the predetermined value is reached. If it is not the rewrite timing, step 11
The routine proceeds to 1 and shifts to normal engine control. As a result, the engine is ready for starting. If it is a rewrite timing, the process proceeds to the subsequent step 104 to rewrite the flash ROM 14.

More specifically, in step 104, a storage area in the flash ROM 14 is designated as a data rewrite target. In this case, the data rewriting of the flash ROM 14 is performed in units of blocks of the flash ROM 14.
Then, each storage area (each block) of the flash ROM 14
Are specified one by one. In the following step 105, all programs and data in the specified storage area are temporarily stored in the RAM 13. Since the amount of data temporarily stored in the RAM 13 is one block of the flash ROM 14, even if the storage area of the RAM 13 is small, flash ROM data can be temporarily stored.

Thereafter, in step 106, the storage area of the flash ROM 14 designated in step 104 is erased collectively. Then, in step 107, the RAM1
Then, rewriting to the flash ROM 14 is performed using the data stored in the flash ROM 14.

In step 108, a checksum is calculated for the rewritten data, and in step 109, the calculated checksum is compared with a normal sum value. If they match, it is considered that rewriting has been performed normally, and the process proceeds to step 110. Step 11
At 0, it is determined whether or not data rewriting has been completed for all storage areas of the flash ROM 14. If NO, the process returns to step 104 and rewrites data for the next storage area. When the data rewriting has been completed for all the storage areas of the flash ROM 14, the process proceeds to step 111, and shifts to normal engine control.

On the other hand, if the checksum does not match the normal sum value in step 109 and the step is NO,
Proceeding to step 112 assuming that a writing error has occurred,
Perform predetermined fail-safe processing. Specifically, a warning lamp is turned on, and starting of the engine is prohibited. If the checksum of the rewrite data does not match the normal sum value, the rewrite is repeated, for example, about three times. If the rewrite still cannot be performed normally, it is determined that the step 109 is NO (abnormal write). good.

Incidentally, a program indicating the data rewriting procedure of FIG. 2 is also stored and held in the flash ROM 14, and rewriting is performed as necessary. When rewriting the rewriting program, the program itself is moved to the RAM 13 and
It is better to operate in the area and execute rewriting.

According to the embodiment described above, the following effects can be obtained. Rewriting of data in the flash ROM 14 is limited to the time when the IG switch 22 is turned on,
Normal engine control starts after writing is completed,
Data rewriting of the flash ROM 14 can be appropriately performed without any trouble in engine control.

Further, since data is rewritten in units of blocks of the flash ROM 14, there is an advantage that a RAM area required as a temporary storage area can be small.

After rewriting the data in the flash ROM 14, a data check using a checksum is performed on the rewritten data, so that erroneous writing of data can be determined. Therefore, the reliability of the memory data after rewriting is improved.

The present invention can be embodied in the following modes other than the above. When the IG switch 22 is turned off, the data in the flash ROM 14 is rewritten. That is, as a configuration of the power supply system of the ECU 10, a relay circuit (not shown) is generally provided in parallel with the IG switch 22, and when the IG switch 22 is turned off, the power supply of the ECU 10 is delayed for a certain period of time. Main relay control (power supply delay processing) is performed. In such a case, at the time of main relay control (power supply delay processing), it is determined whether or not data rewriting of the flash ROM 14 is necessary. If rewriting is necessary, data rewriting is performed. After the rewriting, the power supply to the ECU 10 is cut off. Also in this configuration, similarly to the above-described embodiment, data rewriting of the flash ROM 14 can be appropriately performed without hindering normal control.

In the above embodiment, the number of times the IG is turned on is counted, and it is determined that the rewrite timing is reached when the count value reaches a predetermined value. However, this may be changed as follows. (1) The number of times the IG switch 22 is turned off is counted, and when the count value reaches a predetermined value, it is determined that it is a rewrite timing. (2) The ECU is provided with a clock function to measure the time interval of data rewriting. Then, when the IG is turned on or the IG is turned off, if the elapsed time from the previous data rewriting has reached a predetermined value (for example, one month), it is determined that it is the rewriting timing. (3) When the IG is turned on or the IG is turned off, if the vehicle travel distance from the previous data rewrite has reached a predetermined distance, it is determined that it is the rewrite timing. (4) When the vehicle-mounted battery is replaced, the replacement history is kept. Then, if there is a history of battery replacement when the IG is turned on or when the IG is turned off, it is determined that it is the rewrite timing. (5) At the time of periodic inspection of the vehicle by a dealer or the like, it is determined that it is a rewrite timing according to a request from an external tool (for example, a diagnostic tool). In this case, instead of temporarily storing data in the flash ROM in the RAM and performing rewriting, program data may be received from an external tool and rewriting may be performed using the received data. When rewriting is performed using data received from an external tool, the reliability of the rewritten data is improved.

Of the various data held in the flash ROM, only the data of high importance is to be rewritten. In this case, since the data rewriting is selectively performed according to the importance, the time required for the data rewriting can be reduced.

Further, in the above embodiment, the flash ROM is used as the "non-volatile memory", but the present invention is not limited to this. For example, a relatively large capacity EEPROM may be used as the nonvolatile memory.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an ECU and its peripheral devices.

FIG. 2 is a flowchart showing a procedure for rewriting data in a flash ROM.

[Explanation of symbols]

10 ECU (electronic control unit), 12 CPU, 13
RAM, 14 ... Flash ROM (non-volatile memory),
15 ... EEPROM, 21 ... battery, 22 ... IG switch (power switch).

Claims (7)

[Claims] 1. An electronic control device comprising a nonvolatile memory which retains various control programs and is electrically rewritable, and which is supplied with power via a power switch, wherein when the power switch is turned on, Judgment of the necessity of rewriting the data in the non-volatile memory is performed. If rewriting is necessary, the same data as the data written in the non-volatile memory is written into the non-volatile memory again. An electronic control unit for starting normal control. 2. A power supply delay process for temporarily delaying actual power supply interruption when a power switch is turned off, comprising a nonvolatile memory which holds various control programs and is electrically rewritable. The electronic control unit determines whether or not it is necessary to rewrite data in the non-volatile memory at the time of the power supply delay process. If rewriting is necessary, the same data as the data written in the non-volatile memory is again stored in the non-volatile memory. An electronic control device, which performs writing and shuts off power supply after rewriting. 3. The method according to claim 1, wherein when it is determined that rewriting is necessary, data in said nonvolatile memory to be written is temporarily stored in a RAM, and then said temporarily stored data is written into said nonvolatile memory. An electronic control unit according to claim 1. 4. The electronic control device according to claim 3, wherein
An electronic control device, wherein the non-volatile memory includes a plurality of storage areas, and performs rewriting for each storage area when it is determined that rewriting is necessary. 5. A nonvolatile memory according to claim 1, further comprising means for counting the number of times the power switch has been turned on or off, and if the count value has reached a predetermined value, it is determined that rewriting of data in said nonvolatile memory is necessary. An electronic control unit according to any one of claims 1 to 4. 6. The electronic control unit according to claim 1, wherein, following the rewriting of the data in the nonvolatile memory, the data is inspected, and the control is shifted to normal control on condition that the inspection result is normal. 7. The electronic control device according to claim 1, wherein only data having a high degree of importance among various data stored in said nonvolatile memory is to be rewritten.