JPS61175826A - Malfunction preventing system of computer for automobile - Google Patents

Abstract

PURPOSE:To prevent a malfunction of an automobile use computer by deciding an interrupting inhibition state or not in a prescribed step, when a regular processing routine is being executed, and making the processing pass through a branch routine for releasing the inhibition state, in case of the interrupting inhibition state. CONSTITUTION:First of all, in a step S1, the first processing routine I which is given by dividing the regular processing routine into prescribed pieces is executed. In a step 2, whether the processing of this time is in an interrupting inhibition state or not is decided, and in case of the interrupting inhibition state, its inhibition state is released in the next step S3. Also, if necessary, after a step S4 for storing a fact that a malfunction has occurred (the interrupting inhibition has been executed) in a RAM, or in the step 2, when it is decided that the processing is not in the interrupting inhibition state, the processing enters into the subsequent processing routine II in a step S5. In such a way, it is eliminated that a CPU disregards an interrupting request, and a serious malfunction is prevented.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a system for preventing malfunctions of automobile computers.

[Conventional technology]

Electronic circuits including control microcomputers installed in automobiles are exposed to adverse environments such as temperature, humidity, vibration, and atmospheric noise, and therefore require advanced electronic technology. With regard to the destruction of electronic equipment, the technology to deal with it has improved significantly due to technological advances, so at this stage we are in a very satisfactory state using these technologies, but the true problem of malfunctions in program control is , it cannot be said that it has been fully resolved. In particular, in a microcomputer that sequentially executes long steps, the introduction of just one noise can cause it to go out of control, causing a serious situation such as a computer malfunction related to engine control, causing the engine to stop while driving. become. Therefore, in order to avoid such a worst-case scenario, we often use filters to prevent noise from entering the electronic control section, and we install external watchdog circuits to periodically monitor the system during the software processing process. “H” state and “L” state for a specific output port
``Pulses in the ``status'' are alternately output as program run signals, monitored by the above-mentioned watchdog circuit, and when it is detected that it has stopped, it is determined that 'CP (J runaway)'' has occurred, and the CPLI and other parts are reset. Recently, there have been proposals such as dedicated ICs for the above-mentioned "watchdog circuit," and a microcomputer with an on-chip watchdog circuit has been announced, but the added circuitry reduces the cost. In addition, the problem of malfunction of this circuit itself will arise.In particular, the decisive flaw of this method is that the malfunction of the CPU has to affect the outside (until the Watsujidog circuit works). , it is not possible to return to the normal state.In the case of multitasking processing that can handle interrupts, if the interrupt disable flag is set due to a malfunction, the necessary interrupts cannot be performed. This can lead to serious problems such as loss of control.

[Problems to be Solved by the Invention] Malfunctions of automobile control computers are extremely rare phenomena, and occur, for example, in one car out of every car.
Unfortunately, this only occurs once per run, but based on the information obtained from various tests, we have found that ignition noise or
It turned out that the problem was caused by changes in the contents held in the registers inside the CPU due to an Fi source surge. That is, C
Even though the PLI is executing a normal program, malfunctions occur due to changes in register contents. In particular, this phenomenon is often observed in multitasking processing in which interrupt processing is performed in addition to the main routine. Therefore, the present invention eliminates ignition noise and
For automobiles, the necessary interrupt processing is maintained within the processing routine in anticipation of the case where an illegal signal is input due to a power surge, etc., affecting the register and setting the interrupt disable flag. The aim is to provide a method for preventing computer malfunctions.

[Means to solve the problem]

For this purpose, the present invention, in a computer having a processing routine capable of handling interrupts, determines whether or not interrupts are disabled at a predetermined step during execution of a normal processing routine, and if interrupts are disabled, The present invention is characterized in that the processing routine is configured to go through a branch routine for canceling the prohibited state.

【Example】

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 shows an example of an automobile-mounted computer that implements the present invention, and is used for engine control such as fuel injection 1 ignition control, or vehicle speed control. In FIG. 1, reference numeral 1 indicates various sensors that supply necessary control parameters to the CPU 6, and these sensors 1 are connected to the input/output crab unit 5 via the input interface 3. Reference numeral 2 denotes various control actuators, which are driven by drive signals output from the input/output crab unit 5 via the output interface 4. The input/output crab unit 5 is connected to the CPU 6 via a pass line 9, and the CPU 6 processes the output of the sensor 1 and outputs commands for driving various actuators 2. In addition, CPU6 has
An interrupt line 10 is connected from the input/output crab unit 5,
CPLIB from input/output crab unit 5 for input/output signals
It is possible to request interrupt processing for. Note that numeral 8 is a ROM containing the CPLIB processing procedure.
7 is a RAM used for temporarily saving data, etc.
and are each connected to the CPU via a path line 9. The input/output crab unit 5 is usually made of general-purpose Sr, and employs a programmable option in which multiple functions are selected by software. , the function is uniquely determined. Next, the malfunction prevention method according to the present invention will be specifically explained using FIG. 2. First, in step S1, a first processing routine <1) given by dividing a normal processing routine into a predetermined number of parts is executed. After this routine is executed, in step S2, the processing at this time is ``Prohibit cutting!''!
It is determined whether or not (the interrupt prohibition flag is set), and if it is in the interrupt prohibition state, the above-mentioned prohibition state is canceled in the next step S3 (the interrupt prohibition flag is returned to "011").Also, if necessary, Store in RAM 7 that a malfunction has occurred (interrupts have been disabled) (step S
4), after step S4, or when it is determined in step S2 that interrupts are not disabled, the subsequent processing routine C) is entered in step S5. In this way, it is possible to monitor whether or not interrupts are disabled during one cycle of the processing routine, and maintain the state in which interrupt processing to the computer is essentially possible. Even if the interrupt request occurs, this problem can be resolved during the program execution process, the CPU 6 will not ignore the interrupt request, and serious malfunctions can be prevented. [1. Advantageous Effects] As described in detail above, the present invention monitors whether interrupts are disabled in the processing routine, cancels the disabled state when the interrupts are disabled, and eliminates noise while the program is in progress. Even if an illegal signal is received and an interrupt prohibition flag is set, it is possible to quickly resolve this and avoid the CPU going out of control by ignoring the interrupt request, thereby preventing malfunctions that would seriously impede operation. It is possible to prevent this from happening. Furthermore, unlike conventional methods, there is no need for an external circuit, so there is no cost increase.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the configuration of a computer for implementing the method of the present invention, and FIG. 2 is a diagram showing an example of a flowchart for implementing the method. 1... Sensor, 2... Actuator, 3... Input interface, 4... Output interface,
5... Input/output crab knit, 6... CPU, 7... R
AM, 8...ROM, 9...Pass line, 10...
・Interrupt line. Patent applicant: Fuji Heavy Industries Co., Ltd. Agent: Patent attorney: Makoto Kobashi Ukiyo Patent attorney: Susumu Murai Figure 1

Claims (1)

[Claims] In a computer that has a processing routine capable of handling interrupts, during the execution of a normal processing routine, it is determined at a predetermined step whether or not interrupts are disabled, and if interrupts are disabled, a branch is executed to release the disabled state. A method for preventing malfunction of an automobile computer, characterized in that the processing routine is structured so as to pass through a routine.