JPH0777101A - On-vehicle electronic controller - Google Patents

Abstract

PURPOSE:To provide a good on-vehicle electronic controller capable of surely preventing errounous data entry to an EEPROM by checking correctness of the data which data is entered in to the EEPROM. CONSTITUTION:A microcomputer(CPU) 1 operated according to a program stored a mask ROM 2 an EEPROM 8 connected to the CPU 1 by a serial signal line and an alarm lamp output 11 for outputting any abnormal pattern when the data read from the EEPROM 8 is not matching the data preliminarily set in the mask ROM 2 are provided, and errounous data entry to the EEPROM 8 can be prevented by monitoring the alarm lamp output 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle-mounted electronic control device using an EEPROM as an external storage element of a microcomputer (CPU).

[0002]

2. Description of the Related Art Conventionally, a vehicle-mounted electronic control unit (hereinafter abbreviated as ECU) of this type is a microcomputer (CPU).
And a peripheral storage element. The non-volatile one of the peripheral storage elements stores programs and data and is generally called a ROM, and there are two types, a mask ROM and a programmable ROM (PROM). Among the PROMs, the EEPROM can rewrite the stored contents by an electric signal from the outside.

A mask RO is used as a peripheral storage element of the ECU.
When M and EEPROM are used, the mask ROM is CP
It is built in the U or arranged externally and stores programs and data. The EEPROM is connected to the CPU via a serial signal line, and sets unique data for each production lot (for example, in the case of an engine control device, fuel injection amount correction data according to the production lot of the engine). EC in EEPROM production line
After mounting on the U, the lot-specific data in the EEPROM is rewritten according to the production lot by externally applying an electric signal. After the ECU is installed in the vehicle, the power is turned on, and the program is started, the CPU is EEPR
The unique data for each lot in the OM is read and used as each control data.

As a result, even if it is necessary to change the data for each production lot of the ECU, it is possible to deal with each production lot by rewriting the data in the EEPROM without changing the program or data in the mask ROM. .

[0005]

However, in the above-described conventional on-vehicle electronic control unit, when wrong data is written in the EEPROM by mistake when writing the EEPROM, for example, the data corrects the fuel injection amount. If so, there is a problem in that the engine is damaged due to abnormal fuel injection.

The present invention solves such a conventional problem by checking the validity of data when writing data to the EEPROM and reliably preventing erroneous data writing to the EEPROM. It is an object of the present invention to provide an excellent in-vehicle electronic control device that can be used.

[0007]

In order to achieve the above object, the present invention provides a microcomputer (CPU) that operates according to a program built in a mask ROM, and an EEPROM connected to this CPU by a serial signal line.
And a warning lamp output for outputting an abnormal pattern when the data read from the EEPROM and the data preset in the mask ROM do not match.

[0008]

Therefore, according to the present invention, when the data read from the EEPROM is erroneously wrong data, an abnormal pattern is output to the warning lamp output because the data set in the mask ROM does not match. By monitoring the output of the warning light, it is possible to prevent erroneous data writing to the EEPROM.

[0009]

1 is a block diagram of an on-vehicle electronic control unit according to an embodiment of the present invention, and FIG. 2 is a flow chart of an EEPROM reading program.

In FIG. 1, reference numeral 1 is a microcomputer (CPU), which contains a mask ROM 2 and a work RAM 3. Various control programs and various initial data are stored in the mask ROM 2. Also, work R
The AM3 is accessed for read data and data in the middle of control processing. An input interface 4 processes various input signals 5 and inputs them to the CPU 1.
Reference numeral 6 denotes an output interface, which outputs various signal outputs processed by the CPU 1 as various output signals 7,
It controls the igniter and each solenoid. 8 is EEP
It is a ROM and is connected to the port of the CPU 1 via two lines (serial signal lines) of a data line 9 and a clock line 10. 11 is a warning light output, EE
Data read from the PROM 8 and the mask ROM 2
If the data set in advance does not match, the abnormal pattern is output.

Next, the operation of the above embodiment will be described with reference to the flow chart shown in FIG. In step a,
Read the recognition data stored in the EEPROM 8,
Next, in step b, it is collated with the recognition data stored in the mask ROM 2. In step c, it is determined whether or not the data read from the EEPROM 8 and the recognition data stored in the mask ROM 2 match. If they do not match, the warning lamp output 11 is turned on in step d. .

As described above, according to the above-described embodiment, in the production line, after mounting the EEPROM 8 on the ECU and writing the data, the power of the ECU is turned on to output the warning light output 1
It is possible to check the legitimacy of the write data in the EEPROM 8 by monitoring 1 externally.

In the above embodiment, the warning lamp output 11 is a fixed output that is turned on as an output indicating a data abnormality, but the warning lamp output 11 may be output as a pulse train.

[0014]

According to the present invention, as is apparent from the above embodiment, the data read from the EEPROM and the mask R
By providing a warning light output that outputs an abnormal pattern when data that is preset in the OM does not match,
When the data set in the EEPROM is erroneous, an abnormal pattern is output to the warning lamp output, and by monitoring the warning lamp output, it is possible to prevent the writing of erroneous data in the EEPROM.

[Brief description of drawings]

FIG. 1 is a block diagram of an on-vehicle electronic control device according to a first embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the embodiment.

[Explanation of symbols]

 1 CPU 2 Mask ROM 3 RAM 4 Input Interface 5 Various Input Signals 6 Output Interface 7 Various Output Signals 8 EEPROM 9 Data Lines 10 Clock Lines 11 Warning Light Output

Claims (1)

[Claims] 1. A microcomputer (CPU) operating according to a program built in a mask ROM, and an EEPROM connected to the CPU by a serial signal line.
And a warning lamp output that outputs an abnormal pattern when the data read from the EEPROM does not match the data preset in the mask ROM.