JPS5920062A - Method for preventing runaway in system having microprocessor - Google Patents

Abstract

PURPOSE:To guarantee the device from runaway, by inputting an output signal to a microprocessor again, collating the signal with an input signal to be a cause of the generation of an output signal, permitting the output again when the result is correct, and stopping the re-output when failed. CONSTITUTION:An output 108 from the microprocessor 101 is inputted as a signal 107 to the processor 101 in a loop circuit 110 with a pulse outputted from a loop signal line 109 in terms of the software just before the output. The signal looped in the circuit 110 is collated with an input signal, and when this signal is correct, an output 106 is obtained via the circuit 110 from the output 108. In this case, a pulse is outputted from a normal pulse line 102. If no pulse is outputted to the line 102, no signal 108 is outputted from the device 101. When the signal 108 is not correct in this way, no pulse is outputted to the line 102 and the device 101 is reset.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a system having a microprocessor (hereinafter referred to as
This paper relates to a method for preventing runaway in a microprocessor system.

Conventionally, this type of runaway prevention method checks a flag determined by a program in memory at one point in the routine that makes up the software loop that controls the microprocessor system, and if the result is correct, a pulse is sent. Insert a program that outputs , or run such an interwoven program periodically to check that the pulse is occurring to confirm that the system is normal and check that the pulse is not occurring. If it did not, it would be considered abnormal and the microprocessor would be reset.

Therefore, even if the microprocessor system is confirmed to be normal, it is not guaranteed that the output signal from this system is correct.

The present invention solves the above problem by re-inputting the output signal and diagnosing whether it is correct by comparing it with the input signal that was the basis for generating the output signal using software, and if the result is correct, re-outputting it. Accordingly, it ensures that the output is correct (by outputting a pulse and making sure that this pulse is output within the expected time to ensure that the microprocessor system is working properly, If it is not confirmed, the microprocessor system is assumed to be in a runaway state and the microprocessor is reset.

Next, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing a conventional example. In Figure 1, if the microprocessor system +0+ is operating normally, a check program installed at one point in the routine that makes up the software loop verifies that the flags in memory are correct. Then, a pulse is output from the normal pulse check line 102.

If the microprocessor is normal, this pulse should be output periodically, so this abnormal periodicity (
The pulse detection circuit +03 determines 1-2 whether the pulse interval is long or the pulse is not output, etc., and outputs a reset pulse to the reset line 104. This allows the microprocessor system to return to a normal state if the program order is incorrect for some reason (runaway state). However, even if pulses are output almost periodically to this normal pulse line 102, the output 10 for the input 105 to the microprocessor
There is no guarantee that 6 is really correct. That is, for example, if the output section of the microprocessor system fails, the periodicity of the pulses from the normal pulse line 102 does not necessarily become abnormal. Therefore, when high reliability is required, the conventional method has the disadvantage that it cannot meet the requirements. FIG. 2 is a block diagram showing one embodiment of the present invention. In FIG. 2, the output 108 from the microprocessor system +0+ is looped in the loop circuit 110 to the input 107 to the microprocessor system by means of a pulse outputted by software on the loop signal line 109 just before the output +08 is output. and the output 106 remains in its previous state. Then, the looped output is inputted again in the loop circuit 110, checked against the input signal that was the basis for generating the output, checked whether this output is correct, and if the output is correct, it is output again. , output 10B passes through loop circuit 110 and becomes output 106. At this time, no pulse is output to the loop signal line 109. -1, a pulse is output from the normal pulse line 102. This pulse is of the same nature as before, and the manner in which the microprocessor system is reset is the same as before.

Also - if no pulse is output on the normal pulse line 102, no output 108 is sent from the microprocessor system and the previous state is maintained. Output 108 like this
Unless it is a correct signal (runaway state), no pulse is output to the normal pulse line 102, so the microprocessor system is reset and no output signal is sent out, so high reliability is maintained.

As described above, the present invention inputs the output signal again, compares it with the input signal that was the basis for generating the output signal, diagnoses whether it is correct, and if the result is correct, re-outputs it and confirms that the output is correct. The high reliability of the microprocessor system is ensured by outputting a pulse to ensure that the microprocessor is normal, and if there is a mistake, the microprocessor is reset without re-outputting. It is possible to return to a normal state from a runaway state while maintaining the output signal, and has the effect of ensuring that the output signal in response to the input signal is correct.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional runaway prevention circuit, and FIG. 2 is a block diagram showing an embodiment of the present invention. 101...Microprocessor system 102...
Normal pulse line 105 mountain Hals detection oog104・
...Reset line 105...Input 106...Output 107...Input 10 to the microprocessor system
8... Output 109 of the microprocessor system
...Loop signal line 110...Loop circuit

Claims (1)

[Claims] (1) In a system having a microprocessor, an output signal is input again and compared with the input signal that was the basis for generating the output signal to diagnose whether it is correct, and if the result is correct, it is output again and output. A microprocessor characterized in that it outputs a pulse to ensure that the signal is correct, uses the pulse to confirm that the microprocessor is normal, and if it is incorrect, resets the microprocessor without re-outputting the signal. A method for preventing runaway in a system having