JPH10247153A - Computing device control method - Google Patents

Abstract

(57) [Problem] In a conventional arithmetic device control method, even if a normal output and an abnormal output from a watchdog timer are repeated due to runaway of the arithmetic device or the like, the power of the arithmetic device is not turned off. It was impossible to prevent the abnormal operation of. SOLUTION: In the arithmetic device control method according to the present invention, a watchdog timer is generated due to runaway of the arithmetic device (1) or the like.
If the normal output and abnormal output are repeated from (3), the power supply (5) is turned off by the detection signal (10a) from the detector (10), the arithmetic unit (1) is stopped, and the equipment malfunction This is a method of preventing operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an arithmetic unit control method, and more particularly, to preventing an abnormal operation of an electronic device or the like connected to an arithmetic unit due to an abnormal state when the arithmetic unit is not restarted even after initialization. Related to new improvements.

[0002]

2. Description of the Related Art Conventionally, a method shown in FIG. 2 is generally employed as this type of arithmetic device control method. In FIG. 2, reference numeral 1 denotes an arithmetic unit including a CPU and the like. A constant-cycle output 2a from a decoder 2 connected to the arithmetic unit 1 and controlled by a control signal 1a receives a watchdog timer (WDT). ) 3, this watchdog timer 3
Are driven by the clock signal 4a from the oscillator 4. The clock signal 4a is input to a clock terminal CLK for driving the arithmetic unit 1, and a + 5V power supply 5 is connected to the arithmetic unit 1. The normal output H and the abnormal output L from the watchdog timer 3 are input to a reset terminal RESET of the arithmetic unit 1.

Next, the operation will be described. First, while the arithmetic unit 1 is operating, software for clearing the watchdog timer at a constant period is included in the operation program, and the constant A generated from the decoder 2 is generated by the address A from the arithmetic unit 1. When the periodic output 2a is input to the watchdog timer 3 and the arithmetic unit 1 is normal, the normal output H is output from the watchdog timer 3 so that the arithmetic unit 1 continues normal operation. On the other hand, if the above-described clearing process is not executed due to a runaway of the arithmetic unit 1 or a memory reading error, an abnormal output L is output from the watchdog timer 3, and the arithmetic unit 1 is initialized and restarted by the abnormal output L. .

[0004]

The conventional arithmetic unit control method has the following problems because it is configured as described above. That is, if the arithmetic unit 1 is not restarted even if it is initialized by the above-mentioned abnormal output from the watchdog timer, or if the abnormality is continuously repeated even after the restart, the arithmetic unit 1 does not operate normally, Various devices operated by the arithmetic unit 1 sometimes perform abnormal operations.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and in particular, an abnormal state of an electronic device or the like connected to an arithmetic unit due to an abnormal state when the arithmetic unit is not restarted even after initialization. An object of the present invention is to provide an arithmetic device control method that prevents operation.

[0006]

According to a method of controlling an arithmetic unit according to the present invention, a watchdog timer is cleared by a fixed period output from a decoder connected to the arithmetic unit, and the watchdog timer is cleared when the clearing process is not performed. In the arithmetic device control method, wherein the arithmetic device is initialized and restarted by an abnormal output from the dock timer, a state in which an abnormal output and a normal output are repeatedly output from the watch dock timer is detected by a detector, This is a method of turning off the power to the arithmetic device.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a preferred embodiment of an arithmetic unit control method according to the present invention.
The same parts as those in the conventional example are denoted by the same reference numerals and will be described. In FIG. 1, reference numeral 1 denotes an arithmetic unit including a CPU and the like. An output 2a from a decoder 2 connected to the arithmetic unit 1 and controlled by a control signal 1a is a well-known watchdog timer (WDT) 3. The watchdog timer 3 is driven by a clock signal 4 a from an oscillator 4. The clock signal 4a is input to a clock terminal CLK for driving the arithmetic unit 1, and a power supply of +5 V is connected to the arithmetic unit 1.

On the output side of the watchdog timer 3, a detector 10 to which a clock signal 4a for inputting a normal output H and an abnormal output L of the watchdog timer 3 is inputted.
The detection signal 10a of the detector 10 is provided by a latching relay 1 provided between the power supply 5 and the arithmetic unit 1.
1 connected.

Next, the operation will be described. Since the normal operation is the same as that of the above-described conventional example, it is omitted here, and only the case where an abnormality occurs will be described. If the clock processing of the watchdog timer 3 is not executed due to a runaway of the arithmetic unit 1 or a memory read error, the watchdog timer 3 is not cleared and the abnormal output L
Occurs, the arithmetic unit 1 is initialized and restarted.
In the case described above, the abnormal output L is detected by the detector 10, and if the abnormal output L does not become the normal output H within the specified time after the occurrence of the abnormal output L, or if the normal output H and the abnormal output H When the output L is repeated, the latching relay 11 (which is always kept on) is latched off by the detection signal 10a from the detector 10, and the supply of the power supply 5 to the arithmetic unit 1 is cut off. Therefore, malfunction and abnormal operation of various devices due to runaway of the arithmetic unit 1 can be prevented.

[0010]

Since the arithmetic unit control method according to the present invention is configured as described above, the following effects can be obtained. That is, when the watchdog timer is not cleared due to a runaway of the arithmetic unit or the like and the reset start of the arithmetic unit is not performed, the power is automatically turned off, and malfunctions of various devices can be prevented beforehand.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an arithmetic device control method according to the present invention.

FIG. 2 is a block diagram showing a conventional method.

[Explanation of symbols]

 Reference Signs List 1 arithmetic unit 2 decoder 2a fixed cycle output 3 watchdog timer 5 power supply 10 detector L abnormal output H normal output

Claims (1)

[Claims] 1. A watchdog timer (3) based on a constant period output (2a) from a decoder (2) connected to an arithmetic unit (1).
A clearing process, and when the clearing process is not performed, the calculating device (1) is initialized and restarted by an abnormal output (L) from the watchdog timer (3). A detector (10) detects a state in which an abnormal output (L) and a normal output (H) are repeatedly output from the watchdog timer (3), and
A method for controlling an arithmetic unit, comprising turning off a power supply (5) to (1).