KR19980085727A - How to Prevent Stack Overflow Using the Watchdog Timer's Lighting Values - Google Patents

Abstract

The present invention relates to a stack overflow detection method existing between a memory area A storing a main program and a user-defined memory area B that a user can arbitrarily use for convenience of a specific command or control. In particular, a first step of storing predetermined data in the first memory area of the user-defined memory area B during an initial system operation, and the first step at predetermined time intervals during a normal system operation. A second step of accessing and storing specific data stored in the first memory area of the user-defined memory area B in the watchdog timer area, and determining whether the data stored in the watchdog timer area is predetermined data; In the third step and the third step, the data stored in the watchdog timer area is preset. And a fourth step of resetting the system when it is determined that the data is not the specific data. The stack overflow preventing method using the writing value of the watchdog timer is provided.

Description

How to Prevent Stack Overflow Using the Watchdog Timer's Lighting Values

The present invention is to prevent stack overflow using a watchdog timer for monitoring whether the stack overflows by the occurrence of an interrupt during the operation of each function in the system operation in the control system and monitoring the overflow of the stack. It relates to a method for.

In recent years, with the rapid development of semiconductor chips and the development of electronic technology, digital control has been performed in the analog control method from large electronic systems or buildings and factories to general home appliances.

Thus, the main part constituting each electronic device is modularized into a semiconductor chip, so that each device operates to some degree independently under the control of a microcomputer or a central processing unit and thus transmits operational information to the central processing unit. do.

In this case, since each device performs its function almost independently, the central processing unit provides interrupts or operational priorities according to a specific order in order to prevent their operational conflicts. A program or various information stored in a memory area as shown in FIG. 3 are used as a reference.

In the exemplary diagram of the memory area illustrated in FIG. 1, the location of a stack area provided for storing information received from various devices or information on the next order of a main program which is operating according to the occurrence of various interrupts will be described. It is an exemplary figure for following.

However, since the existing stack area exists between the memory area A storing the main program and the user-defined memory area B that the user can use arbitrarily for convenience of a specific command or control, the stack overflows. Can be used as a stack up to the memory area corresponding to the user area, but in this case, the user-defined data is changed, causing a malfunction or accessing this portion to the user area while the address is stored on the stack. There is a problem that can cause a malfunction by coming in.

An object of the present invention to solve the above problems is to detect the overflow of the stack by using the watchdog timer interrupt, to prevent the malfunction that can occur when the overflow occurs and to reset the stack by resetting the system The present invention provides a method for preventing stack overflow using a watchdog timer that can be prevented.

1 is an exemplary view for explaining a general stack structure in a control system

2 is a flowchart illustrating a stack overflow detection method using a writing value of a watchdog timer according to the present invention.

A feature of the present invention for achieving the above object lies between a memory area A storing a main program and a user-defined memory area B that a user can arbitrarily use for convenience of a specific command or control. A stack overflow detection method comprising: a first step of storing predetermined data in a first memory area of a user-defined memory area (B) during a system initial operation, and at a predetermined time interval while performing a system operation normally; A second step of accessing and storing specific data stored in the first memory area of the user-defined memory area B through the first step in the watchdog timer area; and data stored in the watchdog timer area. A third step of determining whether the specific data is set, and an area of the watchdog timer in the third step If it is determined not to be the specific data stored in the data group it is set to a fourth step of resetting the system.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, looking at the concept of the watchdog to be used in the present invention, its functional feature is to monitor that the system goes into an idle loop due to mechanical failure or enters an unlimited loop due to a program error. A watchdog timer is a watchdog timer that performs a function of causing an alarm when a certain condition is satisfied by a timer set as a program to prevent a malfunction as described above.

2 is a flowchart illustrating a stack overflow detection method using a writing value of a watchdog timer according to the present invention.

In step S101, the CPU determines whether the system is in the initial operation state, and if it is the initial operation, the process proceeds to step S102, in which the specific data preset in the first memory area of the user-defined memory area B (see FIG. For example, 00h). Subsequently, the operation of the normal system is performed in step S103. In this case, in step S104, the data stored in the first memory area of the user-defined memory area B is stored in the watchdog timer area, which is not shown at predetermined time intervals, in step S102. Will be saved.

As described above, it is determined through the process of step S104 whether the data stored in the watchdog timer area is predetermined specific data through the process of step S105. If it is determined that the data is not specific, the process proceeds to step S106, where it is determined that an overflow has occurred in the stack area, and then the system is reset.

When the stack overflow prevention method using the lighting value of the watchdog timer according to the present invention operating as described above is provided, the central processing unit in the electronic control system overflows in a stack structure for temporarily storing a variety of data generated during system operation If is generated, the overflow generated at this time changes the data of the watchdog timer, so that the system reset is performed, thereby preventing the system from malfunctioning.

Claims (1)

In the stack overflow detection method which exists between the memory area A which stores a main program, and the user-defined memory area B which a user can use arbitrarily for the convenience of a specific command or control, A first step of storing predetermined data in a first memory area of the user-defined memory area B during a system initial operation; A second step of accessing specific data stored in the first memory area of the user-defined memory area (B) at a predetermined time interval while performing a system operation normally and storing the specific data in the watchdog timer area; Determining whether data stored in an area of the watchdog timer is predetermined specific data; And And a fourth step of resetting the system when it is determined that the data stored in the area of the watchdog timer is not the predetermined specific data in the third step. Way.