JPH04245547A - Processing abnormality detection system for processor - Google Patents

Abstract

PURPOSE:To eliminate such a problem where the tasks having the priority lower than a watchdog timer access task are kept waiting when the timer access task is started with use of a watchdog timer for detection of the processing abnormality of a processor. CONSTITUTION:The priority of a watchdog timer access task is set at a level lower than any one of other tasks. So that the watchdog timer access task is processed only when other tasks kept in the start states are not required at all.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting processing abnormalities in a processor, and more particularly to a method for detecting processing abnormalities in a microprocessor using a watchdog timer.

0002

2. Description of the Related Art In a microprocessor, a plurality of tasks are provided with individually determined priorities, and an operating system sequentially processes the tasks according to the priorities.

FIG. 3 is a system block diagram showing such a task processing method. In the figure, the operating system 16 sequentially processes tasks 11 to 14 in an activated state in accordance with a task execution order management table 18 managed by a scheduler 17, starting from the task with the highest priority. Note that 15 indicates an idle task.

[0004] To detect such a processing abnormality in a microprocessor, a watchdog timer is used which outputs an alarm to the outside when no access is made by the microprocessor within a predetermined period of time.

FIG. 2 is a block diagram illustrating an outline of a microprocessor processing abnormality detection method using this watchdog timer. The watchdog timer activation control task 22 uses a timer 23 to periodically activate the watchdog timer access task 21.

[0006] Here, if an abnormality occurs during the processing of a certain task and the processing is interrupted, the watchdog timer access task 21 is not activated, and therefore the abnormality is output to the outside.

[0007] In this conventional microprocessor processing abnormality detection method, in addition to the drawback that the timer 23 is occupied by the watchdog timer, the timer 23 is also Since the watchdog timer access task 21 is started unconditionally when the watchdog timer access task is uploaded, tasks with a lower priority than the watchdog timer access task will not be processed until the watchdog timer access processing is completed, which will reduce the processing speed. It has the disadvantage that it decreases.

[0008]

OBJECTS OF THE INVENTION An object of the present invention is to provide a method for detecting processing abnormalities in a processor that enables abnormal processing without using a timer and improves processing speed.

[0009]

According to the present invention, there is provided a watchdog timer that outputs an alarm to the outside when no access is made by a processor for a predetermined period of time, and a watchdog that accesses the watchdog timer at intervals of the predetermined period of time. A processing abnormality detection method for a processor that has a timer access task and a plurality of tasks each having individually determined priorities, and the tasks are sequentially processed according to the priorities by an operating system, wherein the watchdog timer A processing abnormality detection method is obtained in which the access task is given the lowest priority among all tasks.

0010

Embodiments Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a task configuration in a microprocessor processing abnormality detection method used in an embodiment of the present invention. There are n tasks #1 to #n each having a predetermined priority, and an independent watchdog timer access task having a lower priority than these tasks.

[0012] As in the example of the system of FIG. 3, all tasks in the activated state are processed by the operating system according to their priorities. As a result, the watchdog timer access task will be processed for the first time when the task with a higher priority than the watchdog timer access task has finished processing and there are no other tasks in the active state. .

[0013] If the watchdog timer measurement time is set to be longer than the time during which the watchdog timer access task is processed under normal processing conditions, an abnormality may occur in the microprocessor's processing. If processing in that task is stopped, the watchdog timer access task is not processed and a processing abnormality in the microprocessor is detected.

[0014]

[Effects of the Invention] As described above, according to the present invention, by setting the processing priority lower than that of all tasks, it is possible to detect processor processing abnormalities without using a timer, and to detect other tasks. Since the watchdog timer access process is executed when no task is activated, the processing speed of the microprocessor is improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a task configuration used in an embodiment of the present invention.

FIG. 2 is a block diagram showing a conventional microprocessor processing abnormality detection method using a watchdog timer.

FIG. 3 is a block diagram showing a task processing method of the microprocessor system.

[Explanation of symbols]

11-14 Task 16 Operating system 17 Scheduler 18 Task execution order management table

Claims (1)

[Claims] 1. A watchdog timer that outputs an alarm to the outside when the processor is not accessed for a predetermined period of time; a watchdog timer access task that accesses the watchdog timer at intervals of the specified period of time; A processing abnormality detection method for a processor has a plurality of tasks having priority orders determined by the watchdog timer access task, and the tasks are processed sequentially according to the priority orders by an operating system, wherein the priority order of the watchdog timer access task is A processing abnormality detection method characterized by placing the task at the lowest level among all tasks.