JPH0117180B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an abnormality processing device for a microcomputer.

With recent advances in electronic technology, microcomputers (hereinafter referred to as MPUs) are as easy to use as conventional electronic components and are widely used in everything from industrial equipment such as various control devices to household appliances. It is being done.

As a result, a problem unique to the MPU (i.e., a state in which the instruction code, etc. is destroyed by external noise, etc., and normal operation does not return even after the noise, etc. disappears).
However, if you turn off the power to the device and then turn it on again, it will return to normal operation. ) are occurring frequently and are becoming a major problem.

Furthermore, in the case of industrial equipment, the purposes for which MPUs are used are becoming more sophisticated, and the MPUs are used at the core of the equipment, so this type of failure immediately leads to equipment failure.

To give an example of the above-mentioned MPU-specific failure, ultrasonic vehicle detectors installed on general roads
Many MPU failures occur. The main cause is the high-power radio waves emitted by illegal wireless communication devices installed on vehicles traveling on the road. The mechanism of MPU failure occurrence in ultrasonic vehicle detectors will be explained below.

The ultrasonic vehicle sensor has a sensor body 1 and an ultrasonic transmitter/receiver 2, as shown in Fig. 1.
The power supply line 3 that connects the road rises approximately 5.5 meters vertically from the roadside and then extends horizontally. The 5.5m vertical length of the feeder line corresponds to half the wavelength of the 27MHz frequency of illegal wireless communications, so the feeder line becomes an ``antenna.'' As a result, more radio waves than expected penetrate into the sensor body 1, the software of the MPU used inside is temporarily destroyed, and the vehicle sensor stops functioning.

Here, to explain in more detail about the temporary destruction of the MPU software, the role of the MPU is determined by the operating procedure (software) written in detail in the storage element ROM. When the MPU decodes the procedures written in this ROM, if the data (instructions) are destroyed by noise or other factors that have entered from the aforementioned "antenna," the MPU will perform incorrect operations. Once the operating procedure goes awry, the next procedure will become invalid or destroyed, and unless the MPU is returned to its initial state, unpredictable and random operations will continue forever. This is an MPU
This is an unprecedented failure caused by using .

In addition to the noise caused by the above-mentioned illegal wireless communication devices, the noise etc. may include noise caused by power supply abnormalities, lightning strikes, etc.
In order to protect the equipment, technology is needed to prevent these noises from entering the equipment.
An object of the present invention is to detect abnormal operation of the MPU due to the above-mentioned noise, etc., and promptly restart the MPU from its initial state, thereby preventing equipment from stopping. In the past, a watchdog method was generally used to deal with MPU software abnormalities. As shown in Figures 2 to 4, this method outputs "1" from the MPU 5 to the external watchdog circuit 6 in the first step of processing, and also outputs "0" in the last step of processing. Therefore, an AC signal (alternate signal of "1" and "0") a is supplied to the outside (watchdog circuit), and if the AC signal is output, it is determined that the MPU is normal. When the AC signal is cut off, the MPU determines that there is an abnormality, and the abnormality display section 7, such as a monitor lamp, is operated using the abnormality determination signal b.

However, according to this method, as shown in Figure 3, even after outputting "1" at the beginning of processing, an error occurs and "bullshit processing" is performed, the process returns to the end. If it outputs "0", the watchdog circuit 6 determines that the MPU is operating normally. In addition, in this method, when an abnormality is detected, the watchdog circuit 6 sends an abnormality determination signal b to forcibly stop the function of the equipment to prevent it from operating randomly, and the abnormality display unit 7 notifies the person of the abnormality. In order to restore the MPU to normal operation, it was necessary to turn the power back on with human intervention. Therefore, conventional equipment using MPUs has the disadvantage of long downtime due to abnormalities.

In this way, as mentioned above, this invention can promptly detect when an abnormality occurs in the MPU, and
The purpose is to automatically restart the MPU from its initial state, minimizing downtime and increasing the reliability of devices that use the MPU.

Next, an embodiment of the present invention will be described based on the drawings from FIG. 5 onwards.

In order to achieve the above object, this invention has the following features:
In addition, a route check counter 9 is provided inside the software processing routine of the MPU 8. This route check counter 9, as shown in FIG.
Add (-1) or subtract (-1) for each processing step or at least for each branch instruction;
In addition, the configuration is such that the content of the counter becomes 0 at the end of the process if the normal route is successfully passed. In this case, if the subtraction operation is performed immediately after the addition operation at the front stage of the process so that the value becomes 0 at a stage other than the final stage of the process, an abnormality will not occur even if the front stage of the process is jumped. This may cause the inconvenience of not being detected.
It is preferable to perform an addition operation in the first half of the process and a subtraction operation in the second half so that the contents of the route check counter do not become 0 during the process under normal operation.

Also, inside the software processing routine of the MPU 8, it is determined whether the content of the route check counter is "0" at the end of processing, and each time it becomes "0", the output level is switched alternately between high and low. Means 10 is provided for outputting a route check signal c to notify the outside that the MPU is operating normally. That is,
This normal display means operates to check whether the content of the route check counter 9 is "0" at the end of processing, and if the content is "0", the previous route check signal is "1" (high). When the route check signal is "1", it is set to "0", and when it is "0", it is set to "1" and output.

With the above configuration added to the MPU, each time normal processing is completed, the route check counter 9
Check the contents of , and if it is "0",
When the MPU determines that it has passed through the regular route and is operating normally, the route check signal, which had been outputting "1", is changed to "0" and "0".
is output, it is set to "1" and an AC signal is output to the outside.

On the other hand, when the content of the route check counter is other than "0", the route check signal is left as "1" or "0" and output to the outside. For example, if the process jumps due to an abnormality as indicated by the chain line in Figure 6, the content of the route check counter becomes -2.
The MPU no longer outputs AC route check signals to the outside.

In this invention, outside the MPU8,
A means 11 for detecting that the route check signal (AC signal) is no longer output, and an initializing pulse e given to the MPU 8 based on the abnormality detection signal from this detecting means to return the MPU to its initial state. Initialization means 12 is also provided. The detection means 11 can be constituted by a detection circuit as shown in FIG. 7 which outputs only while an AC signal is input, and the initialization means 12 can be constructed by a detection circuit as shown in FIG. A differential amplifier circuit 14 receives the output of the detection means via a buffer circuit 13, and includes resistors _R1 to _R6 , capacitor C, and diodes _D1 to _D3.
It can be composed of Note that R ₁ = R ₂ = R ₃ ,
R ₄ > R ₅ > R ₆ .

To explain in more detail the operations of the additional means 9 and 10 inside the MPU and the means 11 and 12 provided outside, first, when the AC route check signal c is output from the MPU 8, the detection means 1
1 gives the normality detection signal d to the initialization means 12, so the initialization means does not generate an initialization pulse to the MPU, but the route check counter 9 of the MPU 8 does not become 0 at the end of processing, and the route check signal If it becomes "1" or "0" continuously, the detection means 11 gives an abnormality detection signal to the initialization means 12 to inform the MPU that an abnormality has occurred.

Here, the reason why the route check signal when the MPU is normal is AC is so that an abnormality can be detected regardless of whether the MPU output is "1" or "0" when a fault occurs. .

The initialization means 12 generates an initialization pulse e for t ₁ (seconds) after t ₀ (seconds) after receiving the abnormality detection signal from the detection means 11.
Give to MPU8. Although the delay time t ₀ (seconds) does not actually need to be provided, it is provided to remove pulse noise. In addition, t ₁ (seconds) is the time required to force the MPU to jump to the initialization routine, and after the initialization pulse e disappears.
The MPU is restarted from the initialization routine. The initialization means 12 includes a differential amplifier circuit 14 and a resistor.
If it is configured with an astable multivibrator consisting of R ₆ and capacitor C, if restarting the MPU by the first initialization pulse fails, R ₆
After the time constant t ₂ (seconds) of C, an initialization pulse is given to the MPU again to restart it.
That is, the initialization pulse e is generated at a cycle of t ₁ +t ₂ until the MPU operates normally. In this way, the initializing means 12 can be simply composed of an astable multivibrator, and has an extremely simple circuit configuration.

Furthermore, due to C and _R6 , the initialization pulse is sent to the MPU even when the power is turned on, as shown by e' in Figure 9.
given to.

As described above, according to the present invention, the MPU includes a route check counter whose count value becomes 0 at the end of processing when the MPU operates normally along a predetermined route, and a route check counter whose count value becomes 0 at the end of processing. A means is provided to notify the outside that the MPU is operating normally by outputting an AC route check signal every time the MPU is operated, and an extremely simple additional circuit for detection means and initialization means is provided outside the MPU. Even if the MPU software is temporarily destroyed and malfunctions for some reason, the abnormality will be detected immediately and the MPU will be able to automatically restart from the initial state and prevent downtime. Since the time is almost nonexistent, the reliability of devices that use MPUs is greatly improved.

As mentioned at the beginning, MPUs have been increasingly used as electronic components in recent years, and installing a large-scale monitoring circuit to prevent disturbances caused by external noise, etc., as mentioned above, would diminish the meaning of using MPUs. There are many devices that The present invention, which requires a very small number of external additional circuits, is considered to be extremely effective when applied to these devices.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the installation state of an ultrasonic vehicle detector as an example of a device using a microcomputer, Fig. 2 is a block diagram showing a conventional device, and Fig. 3
The figure is a flowchart showing the processing contents of the conventional device, and FIG. 4 is a time chart of the conventional device. Fig. 5 is a block diagram showing the configuration of the abnormality processing device according to the present invention, Fig. 6 is a flowchart showing the processing contents of the device, Fig. 7 is a circuit diagram showing a specific example of the detection means, and Fig. 8 is the initial stage. FIG. 9 is a circuit diagram showing a specific example of the converting means, and a time chart illustrating the operation of the abnormality processing device according to the present invention. 8...Microcomputer, 9...Route check counter, 10...Normal display means, 11...
...Detection means, 12...Initialization means, c...Route check signal, d...Detection signal, e...Initialize pulse.

Claims (1)

[Claims] 1. (a) Inside the software processing routine of the microcomputer, (i) Addition (+1) at least for each branch instruction;
or subtract (-1), and provide a route check counter whose count value becomes 0 at the end of the process when the regular route has passed, and (ii) set the value of the route check counter at the end of the process. A means is provided to notify the outside that the system is operating normally by outputting a route check signal, which is an AC signal whose output level is alternately switched between high and low each time the content becomes "0". ) External to the microcomputer, (i) detecting means for detecting that the alternating current output of the route check signal has disappeared; and (ii) providing an initializing pulse to the microcomputer based on the detection signal of the detecting means. 1. An abnormality processing device for a microcomputer, characterized in that it is provided with initialization means for providing an error. 2. The initializing means is configured with an astable multivibrator to which the detection signal of the detecting means is input, and the initializing pulse is repeatedly applied to the microcomputer until the microcomputer operates normally. The microcomputer abnormality processing device according to item 1.