JPH0474235A - Wrong control preventing circuit - Google Patents

Abstract

PURPOSE:To prevent the output of a wrong control signal to a controlled circuit by deciding the validity of the control signals outputted to a microprocessor and a peripheral circuit based on the input of an alarm signal. CONSTITUTION:A microprocessor/peripheral circuit 3 outputs a state signal 5 to an alarm detection circuit 2 to show the state of a microprocessor. The circuit 2 produces no alarm signal 7 as long as the signal 5 is normal, and a control signal deciding circuit 1 decides a valid control signal 6 outputted from the microprocessor and then outputs a control signal 8. When the microprocessor becomes abnormal, the circuit 2 produces the signal 7. Thus the circuit 1 decides a valid signal 6 sent from the microprocessor and then stops the output of the signal 8. As a result, the malfunction of a controlled circuit can be evaded.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides a system in which a microprocessor and peripheral circuits control a target controlled circuit, and in particular, a system in which a microprocessor and a peripheral circuit control a target controlled circuit. The present invention relates to an error control prevention circuit that prevents control signals from being output.

[Conventional technology]

Conventionally, in systems that use a microprocessor and peripheral circuits to control the target controlled circuit, if the microprocessor becomes abnormal, it can be artificially reported to a human by using an LED or a buzzer. A method has been used to prevent the output of error control signals by stopping the operation of the microprocessor.

[Problem to be solved by the invention]

The above-described conventional error control prevention circuit is a method of stopping a microprocessor that has artificially become abnormal, so it has the disadvantage that error control cannot be promptly prevented and the controlled circuit continues to malfunction.

[Means to solve the problem]

The error control prevention circuit of the present invention includes a microprocessor and a peripheral circuit that have a function of outputting a status signal indicating normality or abnormality of the device, an alarm detection circuit that detects the status signal and generates an alarm signal, and the microprocessor. and a control signal determination circuit that determines the validity of the control signal output from the peripheral circuit based on the input of the alarm signal and outputs the control signal to the controlled circuit.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention.

This embodiment detects a microprocessor and peripheral circuit 3, a controlled circuit 4 controlled by the microprocessor and peripheral circuit 3, and a signal indicating the status of the microprocessor and peripheral circuit 3, and generates an alarm signal 7. The validity of the control signal 6 output from the alarm detection circuit 2, the microprocessor, and the peripheral circuit 3 is determined based on the alarm signal 7, and only when the control signal 6 is valid, the control signal 8 is sent to the controlled circuit 4.
It consists of a control signal determination circuit 1 that outputs.

Next, the operation of this embodiment will be explained. The microprocessor and peripheral circuit 3 outputs a status signal 5 indicating the status of the microprocessor to the alarm detection circuit 2. While the status signal 5 indicating the status of the microprocessor is normal, the alarm detection circuit 2 does not generate the alarm signal 7. Therefore, the control signal determination circuit 1 determines that the control signal 6 output from the microprocessor is valid and outputs the control signal 8 while the alarm signal 7 is not input. When the microprocessor becomes abnormal, the alarm detection circuit 2 generates an alarm signal 7, and the control signal determination circuit 1 determines that the control signal 6 output from the microprocessor is valid and stops outputting the control signal 8. .

〔Effect of the invention〕

As explained above, the present invention provides an alarm detection circuit that outputs an alarm signal when the microprocessor and peripheral circuits are abnormal, and a control signal determination circuit that outputs or stops the control signal depending on the presence or absence of the alarm signal. This has the effect of preventing the controlled circuit from continuing to malfunction.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Control signal determination circuit, 2... Alarm detection circuit, 3... Microprocessor and peripheral circuit, 4...
Controlled circuit, 5... microprocessor status signal;
6... Microprocessor control signal, 7... Alarm signal, 8... Control signal.

Claims (1)

[Claims] a microprocessor and a peripheral circuit that have a function of outputting a status signal indicating normality or abnormality of the device; an alarm detection circuit that detects the status signal and generates an alarm signal;
An error control prevention circuit comprising: a control signal determination circuit that determines the validity of control signals output from the microprocessor and peripheral circuits based on the input of the alarm signal, and outputs the control signal to the controlled circuit.