Automotive controller maintaining operation of controlled device when a microcomputer overruns and cannot be reset

• US 6,219,598 B1
• Filed: 02/11/1998
• Issued: 04/17/2001
• Est. Priority Date: 02/12/1997
• Status: Expired due to Fees

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Miwa, Toshimasa, Kamishima, Hiroyuki, Imai, Masakazu, Yamamoto, Isao, Sasaki, Tetsuo
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): Hernandez, Olga
• Application Number:
  US09/022,031
• Time in Patent Office: 1,161 Days
• Field of Search: 701/36, 701/33, 701/35, 701/29, 701/34, 701/30, 340/438, 340/458
• US Class Current: 701/36
• CPC Class Codes: B60R 16/03 for supply of electrical power to vehicle subsystems or for circuit arrangements for charging batteries H02J7/00
• CPC Class Codes: H02J 1/14 Balancing the load in a network
• CPC Class Codes: H02J 2310/46 for ICE-powered road vehicles
• CPC Class Codes: H02J 9/005 using a power saving mode for copiers G03G15/5004

Abstract

A control system keeps a controlled device operating even when a microcomputer of the system overruns during operation of the controlled device. The control system includes a microcomputer which outputs an operating signal to operate a vehicle-mounted device when the qualifications of operation of the device are met and which outputs a program run signal representing that a control program is being normally executed by the microcomputer and a sleep signal representative of a sleep condition/low power consumption condition of the microcomputer, a watch dog timer which, when the microcomputer fails to output the program run signal, resets the microcomputer and when the microcomputer outputs the sleep signal stops the resetting of the microcomputer, an auxiliary operating circuit which, with a key switch of a motor vehicle kept ON and the sleep signal output from the microcomputer, outputs an auxiliary operating signal of the device subject to meeting of operating qualifications of the device, and a drive circuit which drives the vehicle-mounted device when receiving the operating signal from either one or the microcomputer and the auxiliary operating circuit.

Claims

1. A control system for a device used on a vehicle, comprising:

at least one circuit element outputting a signal corresponding to a condition used to control operation of the device;

a first controller receiving the signal from said at least one circuit element and outputting a first control signal to operate the device, the first controller outputting also a reset prevent signal when the first controller cannot be reset;

a monitoring circuit configured to detect occurrence of an abnormality in operation of the first controller which will halt outputting of the first control signal, and to reset the first controller when the abnormality is detected and the reset prevent signal is not output by the first controller to maintain outputting of the first control signal; and

a second controller configured to output a second control signal to operate the device in response to receipt of the signal from the at least one circuit element and the reset prevent signal from the first controller.

2. The control system according to claim 1, wherein

the first controller outputs an operation indicating signal when operating normally, and

the monitoring circuit detects that the abnormality occurs in the first controller when the operation indicating signal is not output from the first controller.

3. The control system as defined in claim 1, wherein

the first controller comprises a microcomputer outputting an operation indicating signal when operating normally,

the abnormality is an overrun by the microcomputer during which the operation indicating signal is not output by the microcomputer,

the reset prevent signal is a low-power-consumption mode/sleep mode signal,

the monitoring circuit is a watch dog timer which monitors output of the operation indicating signal from the microcomputer and outputs a resetting signal to the microcomputer when absence of both the operation indicating signal and the low-power-consumption mode/sleep mode signals is detected, and

the second controller is a wired logic, not subject to overrun as is the microcomputer.

4. The control system according to claim 1, wherein

under normal condition of the first controller, said first controller outputs the first control signal in a predetermined cycle, and

said monitoring circuit monitors said first control signal and judges the abnormality in operation of the first controller when failing to receive said first control signal for a predetermined time.

5. The control system as defined in claim 1, wherein

the at least one circuit element includes a key switch, and

the first and the second controllers activate the device when the key switch is closed.

6. The control system as defined in claim 5, wherein

the device comprises a lamp,

the at least one circuit element further includes a light switch disposed inside the vehicle and a light intensity sensor to measure a light intensity around the vehicle,

the first controller outputs the first control signal to turn the lamp on when the key switch is on, the light switch is on, and the light intensity sensor detects the light intensity less than a predetermined level, and

the second controller outputs the second control signal to turn the lamp on when the key switch is on, the light switch is on, the light intensity sensor detects the light intensity less than the predetermined level, and the reset prevent signal is received from the first controller.

7. The control system as defined in claim 5, wherein

the device comprises a wiper motor,

the at least one circuit element further includes a wiper switch disposed inside the vehicle and a rainfall sensor to measure quantity of rainfall around the vehicle,

the first controller outputs the first control signal to operate the wiper motor when the key switch is on, the wiper switch is on, and the rainfall sensor detects the rainfall quantity more than a predetermined level, and

the second controller outputs the second control signal to operate the wiper motor when the key switch is on, the wiper switch is on, the rainfall sensor detects the rainfall quantity more than a predetermined level, and the reset prevent signal is received from the first controller.

8. The control system as defined in claim 5, wherein

the device is constituted by a reverse lamp and buzzer for indicating the vehicle is going backward,

the at least one circuit element further includes a reverse switch closed when a transmission is shifted to a reverse position,

the first controller outputs the first control signal to turn on the reverse lamp and buzzer when the key switch is on and the reverse switch is on, and

the second controller outputs the second control signal to turn on the reverse lamp and buzzer when the key switch is on, the reverse switch is on and the reset prevent signal is received from the first controller.

9. A method for controlling operation of a device used on a vehicle utilizing a first controller capable of being reset when an abnormality in operation of the first controller occurs, comprising the steps of:

detecting a condition used to control the operation of the device;

outputting a first control signal from the first controller to control operation of the device according to the detected condition;

detecting (i) occurrence of an abnormality in operation of the first controller which will improperly halt outputting of the first control signal and (ii) absence of a reset prevent signal output from the first controller;

resetting the first controller to maintain outputting of the first control signal when both the abnormality and absence of the reset prevent signal are detected;

providing the detected condition and reset prevent signal to a second controller; and

outputting a second control signal from the second controller to operate the device according to the detected condition when the first controller cannot be reset due to output of the reset prevent signal from the first controller.

10. A control system for controlling operation of a device used on a vehicle, comprising:

at least one means for providing a signal corresponding to a condition for operation of the device;

a first means for outputting (i) a first control signal for controlling the ON and OFF operations of the device in response to the signal from the at least one means, (ii) an operating condition signal indicative of an operation condition of the first means, and (iii) a reset prevent signal indicating that the first means cannot be reset;

means, responsive to the operating condition signal indicating an abnormality in operation of the first means which will improperly change the device from the ON operation to the OFF operation, and absence of the reset prevent signal, for resetting the first means to prevent improper changing of the device from the ON operation to the OFF operation; and

a second means for outputting a second control signal to control the ON operation of the device in response to the signal from the at least one means and output of the reset prevent signal from the first means.