Denso Corporation

Nippondenso Co., Ltd.

Hirokazu Oguro

Katsumi Takaba

Akihito Iwai

Kazuhiko Nakai

Yuko Yamamoto

Kouichi Oohara

Takayoshi Tamakoshi

A vehicle control system reduces the number of times learned value data is written into an electrically rewritable non-volatile ROM (EEPROM),. Learned value data (attained through learning control operation of a vehicle) is saved into the EEPROM, and then on battery disconnection, it can be transferred from the EEPROM back to an ordinary RAM instead of being lost. Each time engine rotating speed NE reaches a predetermined value (e.g., 500 rpm) after the ignition switch is turned on, a counter is incremented. When the counter reaches a predetermined count (e.g., the learned value data as of that time is written into the EEPROM for safe keeping and the counter is reset. Consequently, learned value data is written into the EEPROM in a manner which requires the vehicle to actually run a number of times, thereby making it possible to safely reduce the number of times the learned value data is written into the EEPROM for safe keeping.

Vehicle control system

Various sensor signals of an engine are A/D-converted by an A/D converter of a sub-microcomputer by an A/D conversion request from a main microcomputer. The A/D conversion is executed a plurality of times within one packet for important parameters in the various sensor signals in the A/D conversion request timing per constant time with a longer time interval than a time required for the A/D conversion by an A/D conversion request timing asynchronous to the A/D conversion request. Thereby, normal ones among a plurality of A/D-converted values A/D-converted by the A/D conversion request of the main microcomputer even if the preceding A/D conversion request is issued asynchronously to the A/D conversion request of the main microcomputer.

Vehicle electronic control using one A/D converter for time-synchronous

When a framing error occurs in a slave unit, the cause of error is analyzed, and an interruption is inhibited or enabled depending on the cause of error thus, optimal data communication can be performed. When an interrupt request is issued, whether or not the interruption is caused by a framing error is determined. If the interruption is affirmatively caused by a framing error, whether or not framing errors occur two or more times is determined. An interruption is not inhibited (i.e., enabled) for a negative determination.

Communication system with framing error detection

In a vehicle diagnosis system in which a diagnosis unit is connected to a control unit, the control unit determines whether or not there is a code read request from the diagnosis unit. When there is the request, it further determines whether or not code erase is in execution. When code erase is not in execution, an abnormality code stored in the standby RAM region of its CPU is searched for and the result is transmitted to the diagnosis unit. When code erase is in execution, on the other hand, the data after code erase (no abnormality code) is transmitted to the diagnosis unit. Thus, during code erase operation, the abnormality data before erase is prevented from being transmitted to the diagnosis unit. Further, in case of a RAM value read request is made from a main CPU to other CPU in the controller, it is checked whether a requested address value from the main CPU to the other CPU agrees with the address value transmitted from the other CPU to the main CPU. When the address values agree, the flag XA4ANS is set. After a prescribed interval from this flag setting, the RAM value corresponding to the requested address are responsively sent out to the diagnosis unit. Therefore, transmission of erroneous information to the diagnosis unit can be prevented without fail.

Growing community of inventors

Okazaki, Japan

Hirokazu Oguro